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The use of CO2 in conventional refrigeration systems presents several interesting properties that must be addressed. The pressure/temperature relationship of this refrigerant is one of the primary concerns.
For an example of the pressure/temperature relationship of CO2 as vapor pressure curves see IP units or SI units (PDF files).
The pressures observed with the use of CO2 are much higher than those normally found in ammonia refrigeration systems. Due to the higher pressures found with the use of carbon dioxide it becomes necessary to implement certain principles to limit the pressure increases at higher temperatures. Some of these design guidelines are used to allow standard refrigeration components to be utilized in CO2 refrigeration systems.
A cascade refrigeration system is one method to provide this capability. In this process a separate refrigeration system uses a different refrigerant to condense the CO2. The CO2 is maintained at relatively low pressures by the low temperatures created by the separate refrigeration system. With this type of system configuration, standard refrigeration components are used in the CO2 refrigeration system.
It is common to find ammonia (NH3 or R-717) being used as the higher temperature
In prehistoric times, man found that his game would last during times when food was not available if stored in the coolness of a cave or packed in snow. In China, before the first millennium, ice was harvested and stored.
Hebrews, Greeks, and Romans placed large amounts of snow into storage pits dug into the ground and insulated with wood and straw. The ancient Egyptians filled earthen jars with boiled water and put them on their roofs, thus exposing the jars to the night’s cool air. In India, evaporative cooling was employed. When a liquid vaporizes rapidly, it expands quickly. The rising molecules of vapor abruptly increase their kinetic energy and this increase is drawn from the immediate surroundings of the vapor. These surroundings are therefore cooled.
The intermediate stage in the history of cooling foods was to add chemicals like sodium nitrate or potassium nitrate to water causing the temperature to fall. Cooling wine via this method was recorded in 1550, as were the words "to refrigerate”.
Cooling drinks came into vogue by 1600 in France. Instead of cooling water at night, people rotated long-necked bottles in water in which saltpeter had been dissolved. This solution could be used to produce very low temperatures and to make ice. By the end of the 17th century, iced liquors and frozen juices were popular in French society.
The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. Cullen let ethyl ether boil into a partial vacuum; he did not, however, use the result to any practical purpose.
Ice was first shipped commercially out of Canal Street in New York City to Charleston, South Carolina in 1799. Unfortunately, there was not much ice left when the shipment arrived. New Englanders Frederick Tudor and Nathaniel Wyeth saw the potential for the ice business and revolutionized the industry through their efforts in the first half of the 1800s. Tudor, who became known as the “Ice King”, focused on shipping ice to tropical climates. He experimented with insulating materials and built icehouses that decreased melting losses from 66 percent to less than 8 percent. Wyeth devised a method of quickly and cheaply cutting uniform blocks of ice that transformed the ice industry, making it possible to speed handling techniques in storage, transportation and distribution with less waste.
In 1805, an American inventor, Oliver Evans, designed the first refrigeration machine that used vapor instead of liquid. Evans never constructed his machine, but one similar to it was built by an American physician, John Gorrie.
In 1842, the American physician John Gorrie, to cool sickrooms in a Florida hospital, designed and built an air-cooling apparatus for treating yellow-fever patients. His basic principle--that of compressing a gas, cooling it by sending it through radiating coils, and then expanding it to lower the temperature further--is the one most often used in refrigerators today. Giving up his medical practice to engage in time-consuming experimentation with ice making, he was granted the first U.S. patent for mechanical refrigeration in 1851.
Commercial refrigeration is believed to have been initiated by an American businessperson, Alexander C. Twinning, in 1856. Shortly afterward, an Australian, James Harrison, examined the refrigerators used by Gorrie and Twinning and introduced vapor-compression refrigeration to the brewing and meatpacking industries.
Ferdinand Carré of France developed a somewhat more complex system in 1859. Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. (Ammonia liquefies at a much lower temperature than water and is thus able to absorb more heat.) Carré's refrigerators were widely used, and vapor compression refrigeration became, and still is, the most widely used method of cooling. However, the cost, size, and complexity of refrigeration systems of the time, coupled with the toxicity of their ammonia coolants, prevented the general use of mechanical refrigerators in the home. Most households used iceboxes that were supplied almost daily with blocks of ice from a local refrigeration plant.
Beginning in the 1840s, refrigerated cars were used to transport milk and butter. By 1860, refrigerated transport was limited to mostly seafood and dairy products. The refrigerated railroad car was patented by J.B. Sutherland of Detroit, Michigan in 1867. He designed an insulated car with ice bunkers in each end. Air came in on the top, passed through the bunkers, and circulated through the car by gravity, controlled by the use of hanging flaps that created differences in air temperature. The first refrigerated car to carry fresh fruit was built in 1867 by Parker Earle of Illinois, who shipped strawberries on the Illinois Central Railroad. Each chest contained 100 pounds of ice and 200 quarts of strawberries. It was not until 1949 that a refrigeration system made its way into the trucking industry by way of a roof-mounted cooling device, patented by Fred Jones.
Brewing was the first activity in the northern states to use mechanical refrigeration extensively, beginning with an absorption machine used by S. Liebmann’s Sons Brewing Company in Brooklyn, New York in 1870. Commercial refrigeration was primarily directed at breweries in the 1870s and by 1891, nearly every brewery was equipped with refrigerating machines.
Natural ice supply became an industry unto itself. More companies entered the business, prices decrescendo, and refrigeration using ice became more accessible. By 1879, there were 35 commercial ice plants in America, more than 200 a decade later, and 2,000 by 1909. No pond was safe from scraping for ice production, not even Thoreau’s Walden Pond, where 1,000 tons of ice was extracted each day in 1847.
However, as time went on, ice, as a refrigeration agent, became a health problem. Says Bern Nagengast, co-author of Heat and Cold: Mastering the Great Indoors (published by the American Society of Heating, Refrigeration and Air-conditioning Engineers), “Good sources were harder and harder to find. By the 1890’s, natural ice became a problem because of pollution and sewage dumping.” Signs of a problem were first evident in the brewing industry. Soon the meatpacking and dairy industries followed with their complaints. Refrigeration technology provided the solution: ice, mechanically manufactured, giving birth to mechanical refrigeration.
Carl (Paul Gottfried) von Linde in 1895 set up a large-scale plant for the production of liquid air. Six years later he developed a method for separating pure liquid oxygen from liquid air that resulted in widespread industrial conversion to processes utilizing oxygen (e.g., in steel manufacture).
Though meat-packers were slower to adopt refrigeration than the breweries, they ultimately used refrigeration pervasively. By 1914, the machinery installed in almost all American packing plants was the ammonia compression system, which had a refrigeration capacity of well over 90,000 tons/day.
Despite the inherent advantages, refrigeration had its problems. Refrigerants like sulfur dioxide and methyl chloride were causing people to die. Ammonia had an equally serious toxic effect if it leaked. Refrigeration engineers searched for acceptable substitutes until the 1920s, when a number of synthetic refrigerants called halocarbons or CFCs (chlorofluorocarbons) were developed by Frigidaire. The best known of these substances was patented under the brand name of Freon. Chemically, Freon was created by the substitution of two chlorine and two fluorine atoms for the four hydrogen atoms in methane (CH4); the result, dichlorodifluoromethane (CCl2F2), is odorless and is toxic only in extremely large doses.
Though ice, brewing, and meatpacking industries were refrigeration’s major beneficiaries, many other industries found refrigeration a boon to their business.
In metalworking, for instance, mechanically produced cold helped temper cutlery and tools. Iron production got a boost, as refrigeration removed moisture from the air delivered to blast furnaces, increasing production. Textile mills used refrigeration in mercerizing, bleaching, and dyeing. Oil refineries found it essential, as did the manufacturers of paper, drugs, soap, glue, shoe polish, perfume, celluloid, and photographic materials.
Fur and woolen goods storage could beat the moths by using refrigerated warehouses. Refrigeration also helped nurseries and florists, especially to meet seasonal needs since cut flowers could last longer. Moreover, there was the morbid application of preserving human bodies. Hospitality businesses including hotels, restaurants, saloons, and soda fountains, proved to be big markets for ice.
In WWI, refrigeration in ammunition factories provided the required strict control of temperatures and humidity. Allied fighting ships held carbon-dioxide machines to keep ammunition well below temperatures at which high explosives became unstable.
In 1973, Prof. James Lovelock reported finding trace amounts of refrigerant gases in the atmosphere. In 1974, Sherwood Rowland and Mario Molina predicted that chlorofluorocarbon refrigerant gases would reach the high stratosphere and there damage the protective mantle of the oxygen allotrope, ozone. In 1985 the "ozone hole" over the Antarctic had been discovered and by 1990 Rowland and Molina's prediction was proved correct.
The basic components of today’s modern vapor-compression refrigeration system are a compressor; a condenser; an expansion device, which can be a valve, a capillary tube, an engine, or a turbine; and an evaporator. The gas coolant is first compressed, usually by a piston, and then pushed through a tube into the condenser. In the condenser, the winding tube containing the vapor is passed through either circulating air or a bath of water, which removes some of the heat energy of the compressed gas. The cooled vapor is passed through an expansion device to an area of much lower pressure; as the vapor expands, it draws the energy of its expansion from its surroundings or the medium in contact with it. Evaporators may directly cool a space by letting the vapor come into contact with the area to be chilled, or they may act indirectly--i.e. by cooling a secondary medium such as water. In most domestic refrigerators, the coil containing the evaporator directly contacts the air in the food compartment. At the end of the process, the warmed gas is drawn toward the compressor.
The Impact of Refrigeration
Barbara Krasner-Khait discusses the effect refrigeration had on industry and the home.
IMAGINE LIFE WITHOUT ice cream, fresh fruit, ice cold beer or frozen entrees. Imagine having to go to the grocer every day to make sure your food was fresh. Imagine no flowers to send to that special someone or medicines or computers.
Over the last 150 years or so, refrigeration’s great strides offered us ways to preserve and cool food, other substances and ourselves. Refrigeration brought distant production centers and the North American population together. It tore down the barriers of climates and seasons. And while it helped to rev up industrial processes, it became an industry itself.
To look at refrigeration’s impact on consumers and industry, let us distinguish the refrigeration process from the refrigerator appliance.
Refrigeration is the process of cooling a space or substance below environmental temperature. To accomplish this, the process at first removed heat through evaporation and then later in the 1850s with vapor compression that used air and subsequently ammonia as a coolant. Refrigeration has been around since antiquity. Though its inventor, Maryland farmer Thomas Moore, first introduced the term “refrigerator” in 1803, the appliance we know today first appeared in the 20th century.
Early Refrigeration
Ice was harvested and stored in China before the first millennium. Hebrews, Greeks, and Romans placed large amounts of snow into storage pits and covered this cooling agent with insulating material. Need a cool drink? Just mix in melting snow or its resulting water. Or bury your container right into the snow. No snow? Do like the ancient Egyptians: fill your earthen jar with boiled water and stick it on your roof, exposing it to the night’s cool air.
Cooling drinks was popular particularly in Europe’s southern climates, especially Italy and Spain. It became en vogue by 1600 in France. By this time, instead of cooling water at night, people rotated long-necked bottles in water in which saltpeter was dissolved. This solution, it was discovered, could be used to produce very low temperatures and to make ice. By the end of the 17th century, iced liquors and frozen juices were popular in French society.
For centuries, people preserved and stored their food — especially milk and butter — in cellars, outdoor window boxes or even underwater in nearby lakes, streams or wells. Or perhaps they stored food in a springhouse, where cool running water from a stream trickled under or between shelved pans and crocks. But even these methods could not prevent rapid spoilage, since pasteurization was not yet known and bacterial infestation was rampant. It was not unusual in colonial days to die of “summer complaint” due to spoiled food during warm weather.
Before 1830, food preservation used time-tested methods: salting, spicing, smoking, pickling and drying. There was little use for refrigeration since the foods it primarily preserved — fresh meat, fish, milk, fruits, and vegetables — did not play as important a role in the North American diet as they do today. In fact, the diet consisted mainly of bread and salted meats.
Consumer demand for fresh food, especially produce, led to diet reform between 1830 and the Civil War, fueled by the dramatic growth of cities and the improvement in economic status of the general populace. And as cities grew, so did the distance between the consumer and the source of the food.
The Ice Revolution
Ice was first shipped commercially out of Canal Street in New York City, where it was cut, to Charleston, South Carolina in 1799. Unfortunately, there wasn’t much ice left when the shipment arrived. New Englanders Frederick Tudor and Nathaniel Wyeth saw the potential for the ice business and revolutionized the industry through their efforts in the first half of the 1800s. Tudor, who became known as the “Ice King,” focused on shipping ice to tropical climates. He experimented with insulating materials and built ice houses that decreased melting losses from 66 percent to less than 8 percent. Wyeth devised a method of quickly and cheaply cutting uniform blocks of ice that transformed the ice industry, making it possible to speed handling techniques in storage, transportation and distribution with less waste.
Natural ice supply became an industry unto itself — and a large one at that. More companies entered the business, prices decreased, and refrigeration using ice became more accessible. By 1879 there were 35 commercial ice plants in America, more than 200 a decade later, and 2,000 by 1909. In 1907, 14-15 million tons of ice were consumed, nearly triple the amount in 1880. No pond was safe from scraping for ice production, not even Thoreau’s Walden Pond, where 1,000 tons of ice were extracted each day in 1847.
But as time went on, ice as a refrigeration agent became a health problem. Says Bern Nagengast, co-author of Heat and Cold: Mastering the Great Indoors (published by the American Society of Heating, Refrigeration and Air-conditioning Engineers), “Good sources were harder and harder to find. By the 1890s, natural ice became a problem because of pollution and sewage dumping.“ Signs of a problem were first evident in the brewing industry. Soon the meat-packing and dairy industries followed with their complaints. Refrigeration technology provided the solution: ice mechanically manufactured, giving birth to mechanical refrigeration.
Refrigeration Redefines Brewing And Meat-Packing
There’s no question that the brewing industry was one of the first to realize the significant benefits that refrigeration offered. German lager beer came to America with the German immigrants in the 1840s, tasting a lot better than American ale. Refrigeration enabled the breweries to make a uniform product all year round. Brewing was the first activity in the northern states to use mechanical refrigeration extensively, beginning with an absorption machine used by S. Liebmann’s Sons Brewing Company in Brooklyn, New York in 1870. Commercial refrigeration was primarily directed at breweries in the 1870s and by 1891, nearly every brewery was equipped with refrigerating machines.
A decade later, refrigeration was introduced in Chicago to the meat-packing industry. Though meat-packers were slower to adopt refrigeration than the breweries, they ultimately used refrigeration pervasively. By 1914 the machinery installed in almost all American packing plants was the ammonia compression system, which had a refrigeration capacity of well over 90,000 tons/day.
The five big packers — Armour, Swift, Morris, Wilson, and Cudahy — owned the expensive equipment extensively, using it in refrigeration cars, branch houses, and other cold storage facilities. This was essential for the distribution of perishable foods on a large scale.
Within the packing plant itself, space for meat chilling and storage was usually cooled by ice in overhead lofts, connected to the area by flues that helped the natural circulation of cold air. With refrigeration, curing became a year-round activity and because animals could be brought to market at any time, not just in winter, meat quality improved.
The Refrigerated Railroad Car
Beginning in the 1840s, refrigerated cars were used to transport milk and butter. By 1860, refrigerated transport was limited to mostly seafood and dairy products. The refrigerated railroad car was patented by J.B. Sutherland of Detroit, Michigan in 1867. He designed an insulated car with ice bunkers in each end. Air came in on the top, passed through the bunkers, and circulated through the car by gravity, controlled by the use of hanging flaps that created differences in air temperature.
The cars helped establish mid-Western cities, especially Chicago and Kansas City, as the slaughter centers of the country and also created regional produce specialization. Consider Georgia peaches, California grapes, peaches, pears, plums, apples and citrus, Washington and Oregon apples, pears, cherries, and raspberries, and of course, Florida citrus. The increasingly widespread distribution of fresh foods expanded markets and helped to create healthier diets of meat, produce, eggs, butter, milk, cheese and fish.
There were different car designs based upon the type of cargo, whether meat or fruit. The first refrigerated car to carry fresh fruit was built in 1867 by Parker Earle of Illinois, who shipped strawberries on the Illinois Central Railroad. Each chest contained 100 pounds of ice and 200 quarts of strawberries. It wasn’t until 1949 that a refrigeration system made its way into the trucking industry by way of a roof-mounted cooling device, patented by Fred Jones.
Safety First
Despite the inherent advantages, refrigeration had its problems. Refrigerants like sulfur dioxide and methylchloride were causing people to die. Ammonia had an equally serious toxic effect if it leaked. Frigidaire discovered a new class of synthetic refrigerants called halocarbons or CFCs (chlorofluorocarbons) in 1928. Then part of General Motors, the company sewed up all the patents. It released CFCs in 1930. And despite its original intent to keep its patents proprietary, this was too big an invention to keep to itself, not to mention it didn’t have its own manufacturing facility. The entire industry was allowed to use the patents and refrigeration technology switched to these new “safe” agents like Freon (which have since been banned for harming the ozone layer).
Without the discovery of CFCs, says Nagengast, “Refrigeration wouldn’t have been pervasive.”
Refrigeration’s Cooling Makes Businesses Hot
Though ice, brewing, and meat-packing industries were refrigeration’s major beneficiaries, many other industries found refrigeration a boon to their business.
In metalworking, for instance, mechanically produced cold was used to help temper cutlery and tools. Iron production got a boost, as refrigeration removed moisture from the air delivered to blast furnaces, increasing production. Textile mills used refrigeration in mercerizing, bleaching, and dyeing. Oil refineries found it essential as did the manufacturers of paper, drugs, soap, glue, shoe polish, perfume, celluloid, and photographic materials.
Fur and woolen goods storage could beat the moths by using refrigerated warehouses. Refrigeration also helped nurseries and florists, especially to meet seasonal needs since cut flowers could last longer. And there was a morbid application — preserving human bodies in the morgue.
Sugar mills, confectioneries, chocolate factories, bakeries, yeast manufacturers, tea companies — all found refrigeration helped their business.
Hospitality businesses including hotels, restaurants, saloons, and soda fountains, proved to be big markets for ice. And there was a defense application. In WWI, refrigeration in munitions factories provided the required strict control of temperatures and humidity. Allied fighting ships held carbon-dioxide machines to keep ammunition well below temperatures at which high explosives became unstable.
The Household Refrigerator
Refrigeration in the home lagged behind industrial applications. But by 1884, one writer noted that refrigerators were as common as stoves or sewing machines in all but the poorest tenements. The use of ice in the home was growing to keep food longer and to cool drinks.
The ice wagon was a familiar site on urban streets. It became an American institution, delivering ice as needed when consumers posted the “Ice Today” sign in their windows. Iceboxes were typically made of wood, lined with tin or zinc and insulated with sawdust or seaweed. Water pans had to be emptied daily.
According to Nagengast, the household refrigerator is one of the greatest unsung inventions. Engineering technology perfected it, made it reliable, and inexpensive enough for widespread ownership. He says, “The household refrigerator changed the way people ate and socially affected the household. They were no longer dependent on ice delivery and they didn’t have to make provisions for it like leaving a key or leaving the door open.” Ice wagons became a thing of the past. By the 1920s, the household refrigerator was an essential piece of kitchen furniture. In 1921, 5,000 mechanical refrigerators were manufactured in the US. Ten years later that number grew past one million and just six years later, nearly six million. Mass production of modern refrigerators began in earnest after WWII. By 1950, more than 80 percent of American farms and more than 90 percent of urban homes had one.
China set its first carbon emissions limits on Thursday and said Chinese Premier Wen Jiabao (pictured) would attend a key environmental summit inCopenhagenin December, signalling a new willingness to tackle climate change.
By News Wires (text)
AFP - China announced its first targets for limiting carbon emissions on Thursday, joining the United States in revealing the stance it will take at next month's high-stakes climate summit.
China will cut the intensity of carbon dioxide emissions per unit of gross domestic product in 2020 by 40 to 45 percent from 2005 levels, a statement from the State Council, or cabinet, said.
"This is a voluntary action taken by the Chinese government based on its own national conditions and is a major contribution to the global effort in tackling climate change," the statement said.
It added that China would face "enormous pressure and special difficulty in controlling greenhouse gas emissions".
The announcement marks the first time China has put specific numbers on a September pledge by President Hu Jintao to reduce the intensity of its carbon emissions as a percentage of economic growth by 2020.
Hu said at the time only that carbon intensity would be reduced by a "notable margin". However, emissions would continue to grow under China's plan.
Carbon intensity refers to emissions per unit of economic activity.
China's announcement came a day after Washington said President Barack Obama would attend the December 7-18 meeting in Copenhagen with an offer to cut US emissions by 17 percent from 2005 levels by 2020.
"This is definitely a very positive step China is taking just one week before Copenhagen," Yang Ailun, Greenpeace China's climate and energy campaign manager, told AFP. "But we think China can do more than this."
China earlier Thursday announced that Premier Wen Jiabao would join dozens of other world leaders at the summit, which was called to seek a successor to the Kyoto Protocol on limiting greenhouse gas emissions.
A foreign ministry spokesman said Wen's attendance would "fully demonstrate the great importance attached by the Chinese government to this issue".
Scientists have warned that without aggressive action, global temperatures could rise dramatically this century with calamitous consequences for world climate, leading to rising sea levels and other grave threats.
Pressure has mounted on China and the United States, the number one and two sources of carbon emissions, to announce substantive steps to limit their carbon emissions and seek a meaningful deal in Copenhagen.
Greenpeace's Yang said the United States had missed an opportunity to put "enormous pressure on China" by not announcing a more ambitious target.
Compared to the 1990 benchmark used by almost every other country, the US target only amounts to something like a four percent reduction from that year's levels, Yang said.
In contrast, the European Union has vowed to reduce its emissions by 20 percent from 1990 levels before 2020, raising the target to 30 percent in the event of an international agreement.
The US pledge, however, also promised steadily increased cuts to 2050, when emissions would be reduced by 83 percent from 2005 levels.
The United States has urged China to take aggressive steps to limit carbon emissions. But Beijing has argued that rich developed nations bear the historical responsibility for carbon build-up in the atmosphere and should shoulder the burden.
China says that as a developing nation, it should be given leeway on emissions as it seeks to grow its economy and alleviate poverty in the nation of 1.3 billion people.
China also has previously set goals of cutting energy consumption per unit of GDP by 20 percent between 2006 and 2010 and getting 10 percent of its power from renewable sources by 2010 and 15 percent by 2020.
Obama's offer reflects numbers in a bill narrowly passed by the House of Representatives in June but yet to be confirmed by the Senate.
A slightly more ambitious bill to come before the Senate early next year talks of a 20 percent reduction from 2005 levels by 2020.
Copenhagen climate change talks stall as CO2 emissions rise - Christian Science Monitor
jeudi, novembre 19, 2009, 09:15 AM - Développement durable
The Copenhagen summit on climate change is looking less likely to produce a binding CO2 emissions reduction agreement as a new study finds that global carbon dioxide emissions increased 29 percent in the past nine years.
Even as the Copenhagen climate change negotiations have moved into the slow lane, greenhouse gas emissions are accelerating, according to new evidence released today.
Negotiators at a preparatory meeting for the December climate summit said on Tuesday that firm commitments from the US and other industrial heavyweights to curb greenhouse gas emissions at the meeting are now looking unlikely. A binding global treaty on emissions was the initial aim of the conference.
Meanwhile, The Global Carbon Project, an international group of climate scientists, released research on Tuesday that found carbon-dioxide (CO2) emissions from power plants, factories, tree-felling and other human activities grew by 29 percent between 2000 and 2008 –a period in which leaders of major industrialized nations took the first fledgling steps to reduce their own emissions and make an international climate treaty work.
The Kyoto Protocol on combating climate change was passed in 1997 by over 180 nations with the intent of reducing global carbon emissions to a 1990 baseline. But in the intervening 12 years emissions have continued to rise, as country's have been unwilling to take the economic hits that reduced emissions are likely to require.
Political leaders are now looking to the US and President Barack Obama to take the lead on climate change, since the US is the second-largest carbon emitter after China. But legislation to curb US emissions is currently stalled in Congress, a factor that also makes broad success in Copenhagen less likely. Also uncertain is aid from the developed world to help poorer countries offset the economic hardships of converting to cleaner power sources.
"We still need more movement," said UN Climate Change head Yvo de Boer in Denmark on Tuesday. "Industrialized countries must raise their targets and financial commitments further... I look to the United States for a numerical mid-term target."
In recent weeks leaders in key countries have signalled that no one should look for a treaty to be approved in Copenhagen next month – a clear hope coming out of global climate talks in Bali in December 2007.
On Sunday Denmark's Prime Minister Lars Lokke Rasmussen suggested that countries aim for a more limited political agreement on reducing emissions and building a financial-aid regime for developing countries, with a legally-binding treaty put off until high-level talks in December 2010 in Mexico City. The UN's Mr. de Boer has said he prefers to see a legal document ready for approval in Bonn sometime in mid-2010.
Emissions up in recession
Despite the global economic slowdown last year, emissions rose 2 percent in 2008. The Global Carbon Project estimates that 2009's deep economic contraction trimmed global emissions by nearly 3 percent, but that short term dip is expected to reverse once recovery takes hold.
Noting that population growth and efforts to improve the standard of living in developing countries are among the underlying forces driving rising emissions, the need to cut CO2 emissions "is a very urgent task," says Taro Takahashi, a researcher at Columbia University's Lamont-Doherty Earth Observatory and one of the study's authors.
The question mark looming over the Copenhagen meeting has been the willingness of industrial nations to cap the increase in global average temperatures to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.
To stand an even chance of achieving that, countries should aim to stabilize atmospheric CO2 concentrations at between 350 and 400 parts per million, according to the Intergovernmental Panel on Climate Change. The Global Carbon Project's latest figures show that CO2 concentration levels have risen to 385 parts per million.
Moreover, the team estimates that where changes in land use, largely deforestation, accounted for 20 percent of human emissions between 1990 and 2000, that figure has fallen to about 12 percent for the 2000 to 2008 period. The emissions update appears in this week's issue of the journal Nature Geophysics.
Remaining uncertainty
No single study represents the final word on what's happening with carbon emissions. And the team acknowledges that more work needs to be done to cope with uncertainties. One key issue involves divvying up the uptake and release of CO2 among the various natural sources and "sinks." The study indicates that forests and oceans took up less CO2 during the 2000-2008 period than they did during the previous decade. They attribute the change to global warming and natural climate swings. Other researchers, however, point out that their work shows no change in the ability of these sinks to soak up CO2.
Still, because the Global Carbon Project was established to help inform political decisions on climate policies, its conclusions are likely to carry weight as negotiators grope their way toward a new climate treaty.
The list of outstanding issues is long, according to Jennifer Morgan, who heads the climate and energy program at the World Resources Institute in Washington. Convincing developed countries to make substantial emissions reductiover 180 nations with the intent of reducing global carbon emissions to a 1990 baseline. But in the intervening 12 years emissions have continued to rise, as country's have been unwilling to take the economic hits that reduced emissions are likely to require.
Political leaders are now looking to the US and President Barack Obama to take the lead on climate change, since the US is the second-largest carbon emitter after China. But legislation to curb US emissions is currently stalled in Congress, a factor that also makes broad success in Copenhagen less likely. Also uncertain is aid from the developed world to help poorer countries offset the economic hardships of converting to cleaner power sources.
"We still need more movement," said UN Climate Change head Yvo de Boer in Denmark on Tuesday. "Industrialized countries must raise their targets and financial commitments further... I look to the United States for a numerical mid-term target."
In recent weeks leaders in key countries have signalled that no one should look for a treaty to be approved in Copenhagen next month – a clear hope coming out of global climate talks in Bali in December 2007.
On Sunday Denmark's Prime Minister Lars Lokke Rasmussen suggested that countries aim for a more limited political agreement on reducing emissions and building a financial-aid regime for developing countries, with a legally-binding treaty put off until high-level talks in December 2010 in Mexico City. The UN's Mr. de Boer has said he prefers to see a legal document ready for approval in Bonn sometime in mid-2010.
Emissions up in recession
Despite the global economic slowdown last year, emissions rose 2 percent in 2008. The Global Carbon Project estimates that 2009's deep economic contraction trimmed global emissions by nearly 3 percent, but that short term dip is expected to reverse once recovery takes hold.
Noting that population growth and efforts to improve the standard of living in developing countries are among the underlying forces driving rising emissions, the need to cut CO2 emissions "is a very urgent task," says Taro Takahashi, a researcher at Columbia University's Lamont-Doherty Earth Observatory and one of the study's authors.
The question mark looming over the Copenhagen meeting has been the willingness of industrial nations to cap the increase in global average temperatures to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.
To stand an even chance of achieving that, countries should aim to stabilize atmospheric CO2 concentrations at between 350 and 400 parts per million, according to the Intergovernmental Panel on Climate Change. The Global Carbon Project's latest figures show that CO2 concentration levels have risen to 385 parts per million.
Moreover, the team estimates that where changes in land use, largely deforestation, accounted for 20 percent of human emissions between 1990 and 2000, that figure has fallen to about 12 percent for the 2000 to 2008 period. The emissions update appears in this week's issue of the journal Nature Geophysics.
Remaining uncertainty
No single study represents the final word on what's happening with carbon emissions. And the team acknowledges that more work needs to be done to cope with uncertainties. One key issue involves divvying up the uptake and release ofCO2 among the various natural sources and "sinks." The study indicates that forests and oceans took up less CO2 during the 2000-2008 period than they did during the previous decade. They attribute the change to global warming and natural climate swings. Other researchers, however, point out that their work shows no change in the ability of these sinks to soak up CO2.
Still, because the Global Carbon Project was established to help inform political decisions on climate policies, its conclusions are likely to carry weight as negotiators grope their way toward a new climate treaty.
The list of outstanding issues is long, according to Jennifer Morgan, who heads the climate and energy program at the World Resources Institute in Washington. Convincing developed countries to make substantial emissions reduction is just one challenge. Convincing major developing countries to slow and eventually reverse their emissions trends is another, as is the need to provide financial aid to poorer countries to buy the technology needed to achieve goals they agree to. Finally, finding a monitoring regime and legal status for enforcement that all countries will accept won't be easy,
"All the major economies coming to Copenhagen are coming ready to fill in those blanks," says Ms. Morgan. These countries are looking for "what the [Obama] administration is able to bring to the table consistent with what Congress is debating" in energy and climate bills it's currently considering.
Yet President Obama, during a summit with Chinese leaders this week, noted that "our aim ... is not a partial accord or a political declaration, but rather an accord that covers all of the issues in the negotiations and one that has immediate operational effect."
Some analysts who have been watching this process since the Kyoto Protocol was hammered out still say much can be accomplished at Copenhagen, even if the result falls short of a legally binding agreement for now.
"A few months before Kyoto, people were throwing up their hands saying nothing could happen. A month before Rio, in the final negotiating session, it was unclear there would be the political will to move an agreement forward for the heads of state," says Alden Meyer, director of strategy and policy for the Union of Concerned Scientists in Washington. "Some of us have seen this movie before. Expectations are high and they should be kept high."
WASHINGTON (Reuters) - The Environmental Protection Agency on Monday cleared the way for regulation of greenhouse gases without new laws passed by Congress, reflecting President Barack Obama's commitment to act on climate change as a major summit opened in Copenhagen.
The EPA ruling that greenhouse gases endanger human health, widely expected after it issued a preliminary finding earlier this year, will allow the agency to regulate planet-warming gases even without legislation in Congress.
The agency could begin to make rules as soon as next year to regulate emissions from vehicle tailpipes, power utilities and heavy industry under existing laws.
Obama and his Democratic allies in Congress will still pursue legislation in Congress, which has been slow to act. But the EPA move gave a timely push to the president's aims of securing short-term limits to harmful emissions.
It was expected to inject some optimism into the two-week United Nations meeting in Copenhagen, which Obama is due to attend next week, but was criticized by some U.S. business groups who fear it could push up costs.
"EPA has finalized its endangerment finding on greenhouse gas pollution and is now authorized and obligated to make reasonable efforts to reduce greenhouse pollutants," said Lisa Jackson, the EPA administrator. "This administration will not ignore science or the law any longer."
The Supreme Court ruled in 2007 that the EPA had the right to regulate emissions of the gases under the Clean Air Act. But under the administration of former President George W. Bush, the EPA said Congress was the right place to frame action.
Business groups said the EPA announcement would hurt the economy and endanger jobs just as the country emerges from a deep recession.
Legislation by Congress would be more palatable politically for Obama, because it would represent a compromise between business, politicians and other interests rather than through an imposed ruling.
STRONGER HAND IN COPENHAGEN
The EPA ruling applies to six gases scientists say contribute to global warming, including the main one, carbon dioxide.
There had been fears that Obama, who has made fighting climate change one of his priorities, would arrive almost empty handed at the U.N. conference because climate legislation has stalled in Congress.
"The EPA move strengthens Obama's hand at Copenhagen," said Joe Mendelson, global warming policy director at the National Wildlife Federation. "It gives him additional authority that if Congress doesn't pass climate legislation, the agency can put the country on the path to meet his climate goals."
Obama will pledge at Copenhagen that the United States, the world's second largest emitter of greenhouse gases, will cut emissions by roughly 17 percent by 2020 from 2005 levels.
World leaders hope to reach an agreement at the meeting on getting rich and developing countries to share the burden in fighting climate change.
The climate bill has been delayed in the U.S. Senate by a debate over a sweeping reform of healthcare, but lawmakers hope to pass a bill in the spring. Climate legislation passed narrowly in the House of Representatives in June.
The Obama administration has always said it prefers legislation over action by the EPA.
CONGRESSIONAL ACTION
If the EPA acts alone it could face a slew of legal challenges, including from business groups who say the action would overstep the administration's authority, as well as from environmentalists who seek stronger steps.
But the administration had pressed the EPA to prod business to support efforts in Congress, and to show the world Washington is committed to fighting climate change.
Democratic Senator John Kerry said the EPA move was meant to spur Congress to act. But he said "imposed regulations by definition will not include the job protections and investment incentives we are proposing in the Senate today."
Republicans said the move was equivalent to imposing an energy tax. "By seeking to sharply curtail carbon dioxide (and thus energy usage), the EPA is in effect working to decrease economic activity," the Republican Study Committee said.
One business group was quick to criticize the EPA.
Keith McCoy, vice president of energy policy at the National Association of Manufacturers said the EPA was moving forward with an agenda that will put additional burdens on manufacturers, cost jobs and drive up the price of energy."
The EPA decision, which now will be open for public review, does not preclude legislation. Any new regulations could take a long time to implement, giving Congress room to act.
Still, big industry could learn about changes soon. Jackson said car makers will know by the end of March about required increases in fuel economy standards for cars built for the 2012 model year.
"All industries will be called upon to reduce carbon emissions," said Dave McCurdy, chief executive of the Alliance of Automobile Manufacturers.
An administration proposal unveiled in September would require a boost fuel efficiency by 40 percent by 2016 and aim to cut carbon emissions by 21 percent by 2030. (Additional reporting by Ayesha Rascoe, Roberta Rampton, Deborah Zabarenko, Tom Doggett, Tom Ferraro in Washington and Richard Cowan in Copenhagen; Editing by Simon Denyer and Chris Wilson)
- Réduction substantielle en termes d'installation (tuyauterie de réfrigération et salle mécanique)
- Diminution assurée de votre facture électrique
- Augmentation de la longévité des compresseurs de réfrigération
- Un temps de dégivrage ultra rapide et une température quasi stable des espaces réfrigérés
- Meilleure conservation des produits : l'augmentation de la température étant négligeable, les produits conservent leur qualité, leur apparence et leur bon goût plus longtemps; le givre sur les produits surgelés est chose du passé
- Élimination des coûts de main-d'oeuvre et d'emballage reliés au conditionnement des produits après le dégivrage : vous en avez terminé avec la perte de sang des viandes et l'humidité qui se forme à l'intérieur des paquets emballés
- Réduction des coûts reliés à l'entretien des comptoirs réfrigérés
In the oceans
There is about 50 times as much carbon dissolved in the oceans in the form of CO2 and carbonic acid, bicarbonate and carbonate ions as exists in the atmosphere. The oceans act as an enormous carbon sink, having “absorbed about one-third of all human-generated CO2 emissions to date.”[25] Generally, gas solubility decreases as water temperature increases. Accordingly the rate of uptake from the atmosphere decreases as ocean temperatures rise.Most of the CO2 taken up by the ocean forms carbonic acid in equilibrium with bicarbonate and carbonate ions. Some is consumed in photosynthesis by organisms in the water, and a small proportion of that sinks and leaves the carbon cycle. Increased CO2 in the atmosphere has led to increasing acidity (strictly, decreasing alkalinity) of seawater and there is some concern that this may adversely affect organisms living in the water. In particular, with decreasing alkalinity, the availability of carbonates for forming shells decreases.[26]Biological role
Carbon dioxide is an end product in organisms that obtain energy from breaking down sugars, fats and amino acids with oxygen as part of their metabolism, in a process known as cellular respiration. This includes all plants, animals, many fungi and some bacteria. In higher animals, the carbon dioxide travels in the blood from the body’s tissues to the lungs where it is exhaled. In plants using photosynthesis, carbon dioxide is absorbed from the atmosphere.Role in photosynthesis
Plants remove carbon dioxide from the atmosphere by photosynthesis, also called carbon assimilation, which uses light energy to produce organic compounds (cellulose, lipids, and various proteins) by combining carbon dioxide and water. Free oxygen is released as gas from the decomposition of water molecules, while the hydrogen is split into its protons and electrons and used to generate chemical energy via photophosphorylation. This energy is required for the fixation of carbon dioxide in the Calvin cycle to make 3-phosphoglycerate that is used in metabolism, to construct sugars that can be used as an energy source within the plant through respiration and as the raw material for the construction of more complex organic molecules, such as polysaccharides, nucleic acids and proteins during growth.Even when greenhouses are vented, carbon dioxide must be introduced into them to maintain plant growth, as the concentration of carbon dioxide can fall during daylight hours to as low as 200 ppm (a limit of C3 carbon fixation photosynthesis[citation needed]). Plants can grow up to 50 percent faster in concentrations of 1,000 ppm CO2 when compared with ambient conditions.[27]Plants also emit CO2 during respiration, and so the majority of plants and algae, which use C3 photosynthesis, are only net absorbers during the day. A growing forest will absorb many tons of CO2 each year, but a mature forest will produce as much CO2 from respiration and decomposition of dead specimens (e.g. fallen branches) as is used in biosynthesis in growing plants.[28] Nevertheless, mature forests are valuable carbon sinks, helping maintain balance in the Earth’s atmosphere. Additionally, and crucially to life on earth, photosynthesis by phytoplankton consumes dissolved CO2 in the upper ocean and thereby promotes the absorption of CO2 from the atmosphere.[29]Toxicity
Main symptoms of Carbon dioxide toxicity, by increasing volume percent in air.[30][31].Carbon dioxide content in fresh air (averaged between sea-level and 10 hPa level, i.e. about 30 km altitude) varies between 0.036% (360 ppm) and 0.039% (390 ppm), depending on the location (see graphical map of CO2).Prolonged exposure to moderate concentrations can cause acidosis and adverse effects on calcium phosphorus metabolism resulting in increased calcium deposits in soft tissue. Carbon dioxide is toxic to the heart and causes diminished contractile force.[31]Toxicity and its effects increase with the concentration of CO2, here given in volume percent of CO2 in the air:- 1%, as can occur in a crowded auditorium with poor ventilation, can cause drowsiness with prolonged exposure. [30]
- At 2% it is mildly narcotic and causes increased blood pressure and pulse rate, and causes reduced hearing. [31]
- At about 5% it causes stimulation of the respiratory centre, dizziness, confusion and difficulty in breathing accompanied by headache and shortness of breath. [31]
- At about 8% it causes headache, sweating, dim vision, tremor and loss of consciousness after exposure for between five and ten minutes.[31]
industrial co2 china
Premier Wen to attend Copenhagensummit as China sets first CO2 limits China set its first carbon emissions limits on Thursday and said Chinese Premier Wen Jiabao (pictured) would attend a key environmental summit inCopenhagenin December, signalling a new willingness to tackle climate change. By News Wires (text) AFP - China announced its first targets for limiting carbon emissions on Thursday, joining the United States in revealing the stance it will take at next month's high-stakes climate summit.China will cut the intensity of carbon dioxide emissions per unit of gross domestic product in 2020 by 40 to 45 percent from 2005 levels, a statement from the State Council, or cabinet, said."This is a voluntary action taken by the Chinese government based on its own national conditions and is a major contribution to the global effort in tackling climate change," the statement said.It added that China would face "enormous pressure and special difficulty in controlling greenhouse gas emissions".The announcement marks the first time China has put specific numbers on a September pledge by President Hu Jintao to reduce the intensity of its carbon emissions as a percentage of economic growth by 2020.Hu said at the time only that carbon intensity would be reduced by a "notable margin". However, emissions would continue to grow under China's plan.Carbon intensity refers to emissions per unit of economic activity.China's announcement came a day after Washington said President Barack Obama would attend the December 7-18 meeting in Copenhagen with an offer to cut US emissions by 17 percent from 2005 levels by 2020."This is definitely a very positive step China is taking just one week before Copenhagen," Yang Ailun, Greenpeace China's climate and energy campaign manager, told AFP. "But we think China can do more than this."China earlier Thursday announced that Premier Wen Jiabao would join dozens of other world leaders at the summit, which was called to seek a successor to the Kyoto Protocol on limiting greenhouse gas emissions.A foreign ministry spokesman said Wen's attendance would "fully demonstrate the great importance attached by the Chinese government to this issue".Scientists have warned that without aggressive action, global temperatures could rise dramatically this century with calamitous consequences for world climate, leading to rising sea levels and other grave threats.Pressure has mounted on China and the United States, the number one and two sources of carbon emissions, to announce substantive steps to limit their carbon emissions and seek a meaningful deal in Copenhagen.Greenpeace's Yang said the United States had missed an opportunity to put "enormous pressure on China" by not announcing a more ambitious target.Compared to the 1990 benchmark used by almost every other country, the US target only amounts to something like a four percent reduction from that year's levels, Yang said.In contrast, the European Union has vowed to reduce its emissions by 20 percent from 1990 levels before 2020, raising the target to 30 percent in the event of an international agreement.The US pledge, however, also promised steadily increased cuts to 2050, when emissions would be reduced by 83 percent from 2005 levels.The United States has urged China to take aggressive steps to limit carbon emissions. But Beijing has argued that rich developed nations bear the historical responsibility for carbon build-up in the atmosphere and should shoulder the burden.China says that as a developing nation, it should be given leeway on emissions as it seeks to grow its economy and alleviate poverty in the nation of 1.3 billion people.China also has previously set goals of cutting energy consumption per unit of GDP by 20 percent between 2006 and 2010 and getting 10 percent of its power from renewable sources by 2010 and 15 percent by 2020.COCA-COLA COMMITS TO CLIMATE-FRIENDLY REFRIGERATION THROUGH ENGAGEMENT WITH GREENPEACE
Investments in supply chain to enable transition to 100 percent HFC-free equipment by 2015
December 03, 2009
- Tell a friend
Source: The Co-operative Group Sustainability Report 2008/09In 2008, refrigerant gas leakage across The Co-operative Food stores was 33.42 tonnes (2007: 41.25 tonnes), with a net GWP equivalent of 104,640 tonnes of CO² (2007: 123,413 tonnes). This 15% reduction was achieved as a result of switching to contractors whose focus has been to reduce leakage through better maintenance of equipment. The Co-operative has decided to go beyond just increased maintenance of equipment to reduce its environmental impact; it has introduced innovative new technology at its Manchester store.
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How the issue was tackled
In July 2007, a new flagship Food store in Manchester became the first in the UK to utilise solely CO² as a refrigerant in both the fridge and freezer cabinets. The store’s heating and cooling system also utilised hydrocarbon refrigerants. Both these gases are significantly better for the environment as they have substantially lower global warming potential when compared to refrigerants found in conventional systems.Benefits and impacts
- Refrigerant emissions from the store are massively reduced and the project is helping the business to understand how it can utilise the technology in the future.
- This project received the Green End-User of the Year Award within the small projects category, at the Cooling Industry Awards 2007.
Advice to others
CO² refrigeration systems are new technology so quickly sourcing replacement parts and breakdown servicing can be a problem.The new systems operate at higher pressures than current conventional refrigeration and therefore require closer management to mitigate the associated risks.samedi 2 janvier 2010
co2 refrigerartion
interest in recent years. As a result, there is also a lack of familiarity with this refrigerant among the general industry.The use of CO2 in conventional refrigeration systems presents several interesting properties that must be addressed. The pressure/temperature relationship of this refrigerant is one of the primary concerns.
For an example of the pressure/temperature relationship of CO2 as vapor pressure curves see IP units or SI units (PDF files).
The pressures observed with the use of CO2 are much higher than those normally found in ammonia refrigeration systems. Due to the higher pressures found with the use of carbon dioxide it becomes necessary to implement certain principles to limit the pressure increases at higher temperatures. Some of these design guidelines are used to allow standard refrigeration components to be utilized in CO2 refrigeration systems.
A cascade refrigeration system is one method to provide this capability. In this process a separate refrigeration system uses a different refrigerant to condense the CO2. The CO2 is maintained at relatively low pressures by the low temperatures created by the separate refrigeration system. With this type of system configuration, standard refrigeration components are used in the CO2 refrigeration system.
It is common to find ammonia (NH3 or R-717) being used as the higher temperature
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mardi 8 décembre 2009
Refrigeration co2 And History
http://www.rsd.qc.caIn prehistoric times, man found that his game would last during times when food was not available if stored in the coolness of a cave or packed in snow. In China, before the first millennium, ice was harvested and stored.
Hebrews, Greeks, and Romans placed large amounts of snow into storage pits dug into the ground and insulated with wood and straw. The ancient Egyptians filled earthen jars with boiled water and put them on their roofs, thus exposing the jars to the night’s cool air. In India, evaporative cooling was employed. When a liquid vaporizes rapidly, it expands quickly. The rising molecules of vapor abruptly increase their kinetic energy and this increase is drawn from the immediate surroundings of the vapor. These surroundings are therefore cooled.
The intermediate stage in the history of cooling foods was to add chemicals like sodium nitrate or potassium nitrate to water causing the temperature to fall. Cooling wine via this method was recorded in 1550, as were the words "to refrigerate”.
Cooling drinks came into vogue by 1600 in France. Instead of cooling water at night, people rotated long-necked bottles in water in which saltpeter had been dissolved. This solution could be used to produce very low temperatures and to make ice. By the end of the 17th century, iced liquors and frozen juices were popular in French society.
The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. Cullen let ethyl ether boil into a partial vacuum; he did not, however, use the result to any practical purpose.
Ice was first shipped commercially out of Canal Street in New York City to Charleston, South Carolina in 1799. Unfortunately, there was not much ice left when the shipment arrived. New Englanders Frederick Tudor and Nathaniel Wyeth saw the potential for the ice business and revolutionized the industry through their efforts in the first half of the 1800s. Tudor, who became known as the “Ice King”, focused on shipping ice to tropical climates. He experimented with insulating materials and built icehouses that decreased melting losses from 66 percent to less than 8 percent. Wyeth devised a method of quickly and cheaply cutting uniform blocks of ice that transformed the ice industry, making it possible to speed handling techniques in storage, transportation and distribution with less waste.
In 1805, an American inventor, Oliver Evans, designed the first refrigeration machine that used vapor instead of liquid. Evans never constructed his machine, but one similar to it was built by an American physician, John Gorrie.
In 1842, the American physician John Gorrie, to cool sickrooms in a Florida hospital, designed and built an air-cooling apparatus for treating yellow-fever patients. His basic principle--that of compressing a gas, cooling it by sending it through radiating coils, and then expanding it to lower the temperature further--is the one most often used in refrigerators today. Giving up his medical practice to engage in time-consuming experimentation with ice making, he was granted the first U.S. patent for mechanical refrigeration in 1851.
Commercial refrigeration is believed to have been initiated by an American businessperson, Alexander C. Twinning, in 1856. Shortly afterward, an Australian, James Harrison, examined the refrigerators used by Gorrie and Twinning and introduced vapor-compression refrigeration to the brewing and meatpacking industries.
Ferdinand Carré of France developed a somewhat more complex system in 1859. Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. (Ammonia liquefies at a much lower temperature than water and is thus able to absorb more heat.) Carré's refrigerators were widely used, and vapor compression refrigeration became, and still is, the most widely used method of cooling. However, the cost, size, and complexity of refrigeration systems of the time, coupled with the toxicity of their ammonia coolants, prevented the general use of mechanical refrigerators in the home. Most households used iceboxes that were supplied almost daily with blocks of ice from a local refrigeration plant.
Beginning in the 1840s, refrigerated cars were used to transport milk and butter. By 1860, refrigerated transport was limited to mostly seafood and dairy products. The refrigerated railroad car was patented by J.B. Sutherland of Detroit, Michigan in 1867. He designed an insulated car with ice bunkers in each end. Air came in on the top, passed through the bunkers, and circulated through the car by gravity, controlled by the use of hanging flaps that created differences in air temperature. The first refrigerated car to carry fresh fruit was built in 1867 by Parker Earle of Illinois, who shipped strawberries on the Illinois Central Railroad. Each chest contained 100 pounds of ice and 200 quarts of strawberries. It was not until 1949 that a refrigeration system made its way into the trucking industry by way of a roof-mounted cooling device, patented by Fred Jones.
Brewing was the first activity in the northern states to use mechanical refrigeration extensively, beginning with an absorption machine used by S. Liebmann’s Sons Brewing Company in Brooklyn, New York in 1870. Commercial refrigeration was primarily directed at breweries in the 1870s and by 1891, nearly every brewery was equipped with refrigerating machines.
Natural ice supply became an industry unto itself. More companies entered the business, prices decrescendo, and refrigeration using ice became more accessible. By 1879, there were 35 commercial ice plants in America, more than 200 a decade later, and 2,000 by 1909. No pond was safe from scraping for ice production, not even Thoreau’s Walden Pond, where 1,000 tons of ice was extracted each day in 1847.
However, as time went on, ice, as a refrigeration agent, became a health problem. Says Bern Nagengast, co-author of Heat and Cold: Mastering the Great Indoors (published by the American Society of Heating, Refrigeration and Air-conditioning Engineers), “Good sources were harder and harder to find. By the 1890’s, natural ice became a problem because of pollution and sewage dumping.” Signs of a problem were first evident in the brewing industry. Soon the meatpacking and dairy industries followed with their complaints. Refrigeration technology provided the solution: ice, mechanically manufactured, giving birth to mechanical refrigeration.
Carl (Paul Gottfried) von Linde in 1895 set up a large-scale plant for the production of liquid air. Six years later he developed a method for separating pure liquid oxygen from liquid air that resulted in widespread industrial conversion to processes utilizing oxygen (e.g., in steel manufacture).
Though meat-packers were slower to adopt refrigeration than the breweries, they ultimately used refrigeration pervasively. By 1914, the machinery installed in almost all American packing plants was the ammonia compression system, which had a refrigeration capacity of well over 90,000 tons/day.
Despite the inherent advantages, refrigeration had its problems. Refrigerants like sulfur dioxide and methyl chloride were causing people to die. Ammonia had an equally serious toxic effect if it leaked. Refrigeration engineers searched for acceptable substitutes until the 1920s, when a number of synthetic refrigerants called halocarbons or CFCs (chlorofluorocarbons) were developed by Frigidaire. The best known of these substances was patented under the brand name of Freon. Chemically, Freon was created by the substitution of two chlorine and two fluorine atoms for the four hydrogen atoms in methane (CH4); the result, dichlorodifluoromethane (CCl2F2), is odorless and is toxic only in extremely large doses.
Though ice, brewing, and meatpacking industries were refrigeration’s major beneficiaries, many other industries found refrigeration a boon to their business.
In metalworking, for instance, mechanically produced cold helped temper cutlery and tools. Iron production got a boost, as refrigeration removed moisture from the air delivered to blast furnaces, increasing production. Textile mills used refrigeration in mercerizing, bleaching, and dyeing. Oil refineries found it essential, as did the manufacturers of paper, drugs, soap, glue, shoe polish, perfume, celluloid, and photographic materials.
Fur and woolen goods storage could beat the moths by using refrigerated warehouses. Refrigeration also helped nurseries and florists, especially to meet seasonal needs since cut flowers could last longer. Moreover, there was the morbid application of preserving human bodies. Hospitality businesses including hotels, restaurants, saloons, and soda fountains, proved to be big markets for ice.
In WWI, refrigeration in ammunition factories provided the required strict control of temperatures and humidity. Allied fighting ships held carbon-dioxide machines to keep ammunition well below temperatures at which high explosives became unstable.
In 1973, Prof. James Lovelock reported finding trace amounts of refrigerant gases in the atmosphere. In 1974, Sherwood Rowland and Mario Molina predicted that chlorofluorocarbon refrigerant gases would reach the high stratosphere and there damage the protective mantle of the oxygen allotrope, ozone. In 1985 the "ozone hole" over the Antarctic had been discovered and by 1990 Rowland and Molina's prediction was proved correct.
The basic components of today’s modern vapor-compression refrigeration system are a compressor; a condenser; an expansion device, which can be a valve, a capillary tube, an engine, or a turbine; and an evaporator. The gas coolant is first compressed, usually by a piston, and then pushed through a tube into the condenser. In the condenser, the winding tube containing the vapor is passed through either circulating air or a bath of water, which removes some of the heat energy of the compressed gas. The cooled vapor is passed through an expansion device to an area of much lower pressure; as the vapor expands, it draws the energy of its expansion from its surroundings or the medium in contact with it. Evaporators may directly cool a space by letting the vapor come into contact with the area to be chilled, or they may act indirectly--i.e. by cooling a secondary medium such as water. In most domestic refrigerators, the coil containing the evaporator directly contacts the air in the food compartment. At the end of the process, the warmed gas is drawn toward the compressor.
The Impact of Refrigeration
Barbara Krasner-Khait discusses the effect refrigeration had on industry and the home.
IMAGINE LIFE WITHOUT ice cream, fresh fruit, ice cold beer or frozen entrees. Imagine having to go to the grocer every day to make sure your food was fresh. Imagine no flowers to send to that special someone or medicines or computers.
Over the last 150 years or so, refrigeration’s great strides offered us ways to preserve and cool food, other substances and ourselves. Refrigeration brought distant production centers and the North American population together. It tore down the barriers of climates and seasons. And while it helped to rev up industrial processes, it became an industry itself.
To look at refrigeration’s impact on consumers and industry, let us distinguish the refrigeration process from the refrigerator appliance.
Refrigeration is the process of cooling a space or substance below environmental temperature. To accomplish this, the process at first removed heat through evaporation and then later in the 1850s with vapor compression that used air and subsequently ammonia as a coolant. Refrigeration has been around since antiquity. Though its inventor, Maryland farmer Thomas Moore, first introduced the term “refrigerator” in 1803, the appliance we know today first appeared in the 20th century.
Early Refrigeration
Ice was harvested and stored in China before the first millennium. Hebrews, Greeks, and Romans placed large amounts of snow into storage pits and covered this cooling agent with insulating material. Need a cool drink? Just mix in melting snow or its resulting water. Or bury your container right into the snow. No snow? Do like the ancient Egyptians: fill your earthen jar with boiled water and stick it on your roof, exposing it to the night’s cool air.
Cooling drinks was popular particularly in Europe’s southern climates, especially Italy and Spain. It became en vogue by 1600 in France. By this time, instead of cooling water at night, people rotated long-necked bottles in water in which saltpeter was dissolved. This solution, it was discovered, could be used to produce very low temperatures and to make ice. By the end of the 17th century, iced liquors and frozen juices were popular in French society.
For centuries, people preserved and stored their food — especially milk and butter — in cellars, outdoor window boxes or even underwater in nearby lakes, streams or wells. Or perhaps they stored food in a springhouse, where cool running water from a stream trickled under or between shelved pans and crocks. But even these methods could not prevent rapid spoilage, since pasteurization was not yet known and bacterial infestation was rampant. It was not unusual in colonial days to die of “summer complaint” due to spoiled food during warm weather.
Before 1830, food preservation used time-tested methods: salting, spicing, smoking, pickling and drying. There was little use for refrigeration since the foods it primarily preserved — fresh meat, fish, milk, fruits, and vegetables — did not play as important a role in the North American diet as they do today. In fact, the diet consisted mainly of bread and salted meats.
Consumer demand for fresh food, especially produce, led to diet reform between 1830 and the Civil War, fueled by the dramatic growth of cities and the improvement in economic status of the general populace. And as cities grew, so did the distance between the consumer and the source of the food.
The Ice Revolution
Ice was first shipped commercially out of Canal Street in New York City, where it was cut, to Charleston, South Carolina in 1799. Unfortunately, there wasn’t much ice left when the shipment arrived. New Englanders Frederick Tudor and Nathaniel Wyeth saw the potential for the ice business and revolutionized the industry through their efforts in the first half of the 1800s. Tudor, who became known as the “Ice King,” focused on shipping ice to tropical climates. He experimented with insulating materials and built ice houses that decreased melting losses from 66 percent to less than 8 percent. Wyeth devised a method of quickly and cheaply cutting uniform blocks of ice that transformed the ice industry, making it possible to speed handling techniques in storage, transportation and distribution with less waste.
Natural ice supply became an industry unto itself — and a large one at that. More companies entered the business, prices decreased, and refrigeration using ice became more accessible. By 1879 there were 35 commercial ice plants in America, more than 200 a decade later, and 2,000 by 1909. In 1907, 14-15 million tons of ice were consumed, nearly triple the amount in 1880. No pond was safe from scraping for ice production, not even Thoreau’s Walden Pond, where 1,000 tons of ice were extracted each day in 1847.
But as time went on, ice as a refrigeration agent became a health problem. Says Bern Nagengast, co-author of Heat and Cold: Mastering the Great Indoors (published by the American Society of Heating, Refrigeration and Air-conditioning Engineers), “Good sources were harder and harder to find. By the 1890s, natural ice became a problem because of pollution and sewage dumping.“ Signs of a problem were first evident in the brewing industry. Soon the meat-packing and dairy industries followed with their complaints. Refrigeration technology provided the solution: ice mechanically manufactured, giving birth to mechanical refrigeration.
Refrigeration Redefines Brewing And Meat-Packing
There’s no question that the brewing industry was one of the first to realize the significant benefits that refrigeration offered. German lager beer came to America with the German immigrants in the 1840s, tasting a lot better than American ale. Refrigeration enabled the breweries to make a uniform product all year round. Brewing was the first activity in the northern states to use mechanical refrigeration extensively, beginning with an absorption machine used by S. Liebmann’s Sons Brewing Company in Brooklyn, New York in 1870. Commercial refrigeration was primarily directed at breweries in the 1870s and by 1891, nearly every brewery was equipped with refrigerating machines.
A decade later, refrigeration was introduced in Chicago to the meat-packing industry. Though meat-packers were slower to adopt refrigeration than the breweries, they ultimately used refrigeration pervasively. By 1914 the machinery installed in almost all American packing plants was the ammonia compression system, which had a refrigeration capacity of well over 90,000 tons/day.
The five big packers — Armour, Swift, Morris, Wilson, and Cudahy — owned the expensive equipment extensively, using it in refrigeration cars, branch houses, and other cold storage facilities. This was essential for the distribution of perishable foods on a large scale.
Within the packing plant itself, space for meat chilling and storage was usually cooled by ice in overhead lofts, connected to the area by flues that helped the natural circulation of cold air. With refrigeration, curing became a year-round activity and because animals could be brought to market at any time, not just in winter, meat quality improved.
The Refrigerated Railroad Car
Beginning in the 1840s, refrigerated cars were used to transport milk and butter. By 1860, refrigerated transport was limited to mostly seafood and dairy products. The refrigerated railroad car was patented by J.B. Sutherland of Detroit, Michigan in 1867. He designed an insulated car with ice bunkers in each end. Air came in on the top, passed through the bunkers, and circulated through the car by gravity, controlled by the use of hanging flaps that created differences in air temperature.
The cars helped establish mid-Western cities, especially Chicago and Kansas City, as the slaughter centers of the country and also created regional produce specialization. Consider Georgia peaches, California grapes, peaches, pears, plums, apples and citrus, Washington and Oregon apples, pears, cherries, and raspberries, and of course, Florida citrus. The increasingly widespread distribution of fresh foods expanded markets and helped to create healthier diets of meat, produce, eggs, butter, milk, cheese and fish.
There were different car designs based upon the type of cargo, whether meat or fruit. The first refrigerated car to carry fresh fruit was built in 1867 by Parker Earle of Illinois, who shipped strawberries on the Illinois Central Railroad. Each chest contained 100 pounds of ice and 200 quarts of strawberries. It wasn’t until 1949 that a refrigeration system made its way into the trucking industry by way of a roof-mounted cooling device, patented by Fred Jones.
Safety First
Despite the inherent advantages, refrigeration had its problems. Refrigerants like sulfur dioxide and methylchloride were causing people to die. Ammonia had an equally serious toxic effect if it leaked. Frigidaire discovered a new class of synthetic refrigerants called halocarbons or CFCs (chlorofluorocarbons) in 1928. Then part of General Motors, the company sewed up all the patents. It released CFCs in 1930. And despite its original intent to keep its patents proprietary, this was too big an invention to keep to itself, not to mention it didn’t have its own manufacturing facility. The entire industry was allowed to use the patents and refrigeration technology switched to these new “safe” agents like Freon (which have since been banned for harming the ozone layer).
Without the discovery of CFCs, says Nagengast, “Refrigeration wouldn’t have been pervasive.”
Refrigeration’s Cooling Makes Businesses Hot
Though ice, brewing, and meat-packing industries were refrigeration’s major beneficiaries, many other industries found refrigeration a boon to their business.
In metalworking, for instance, mechanically produced cold was used to help temper cutlery and tools. Iron production got a boost, as refrigeration removed moisture from the air delivered to blast furnaces, increasing production. Textile mills used refrigeration in mercerizing, bleaching, and dyeing. Oil refineries found it essential as did the manufacturers of paper, drugs, soap, glue, shoe polish, perfume, celluloid, and photographic materials.
Fur and woolen goods storage could beat the moths by using refrigerated warehouses. Refrigeration also helped nurseries and florists, especially to meet seasonal needs since cut flowers could last longer. And there was a morbid application — preserving human bodies in the morgue.
Sugar mills, confectioneries, chocolate factories, bakeries, yeast manufacturers, tea companies — all found refrigeration helped their business.
Hospitality businesses including hotels, restaurants, saloons, and soda fountains, proved to be big markets for ice. And there was a defense application. In WWI, refrigeration in munitions factories provided the required strict control of temperatures and humidity. Allied fighting ships held carbon-dioxide machines to keep ammunition well below temperatures at which high explosives became unstable.
The Household Refrigerator
Refrigeration in the home lagged behind industrial applications. But by 1884, one writer noted that refrigerators were as common as stoves or sewing machines in all but the poorest tenements. The use of ice in the home was growing to keep food longer and to cool drinks.
The ice wagon was a familiar site on urban streets. It became an American institution, delivering ice as needed when consumers posted the “Ice Today” sign in their windows. Iceboxes were typically made of wood, lined with tin or zinc and insulated with sawdust or seaweed. Water pans had to be emptied daily.
According to Nagengast, the household refrigerator is one of the greatest unsung inventions. Engineering technology perfected it, made it reliable, and inexpensive enough for widespread ownership. He says, “The household refrigerator changed the way people ate and socially affected the household. They were no longer dependent on ice delivery and they didn’t have to make provisions for it like leaving a key or leaving the door open.” Ice wagons became a thing of the past. By the 1920s, the household refrigerator was an essential piece of kitchen furniture. In 1921, 5,000 mechanical refrigerators were manufactured in the US. Ten years later that number grew past one million and just six years later, nearly six million. Mass production of modern refrigerators began in earnest after WWII. By 1950, more than 80 percent of American farms and more than 90 percent of urban homes had one.
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lundi 7 décembre 2009
SD Refrigeration
Premier Wen to attend Copenhagensummit as China sets first CO2 limitsChina set its first carbon emissions limits on Thursday and said Chinese Premier Wen Jiabao (pictured) would attend a key environmental summit inCopenhagenin December, signalling a new willingness to tackle climate change.
By News Wires (text)
AFP - China announced its first targets for limiting carbon emissions on Thursday, joining the United States in revealing the stance it will take at next month's high-stakes climate summit.
China will cut the intensity of carbon dioxide emissions per unit of gross domestic product in 2020 by 40 to 45 percent from 2005 levels, a statement from the State Council, or cabinet, said.
"This is a voluntary action taken by the Chinese government based on its own national conditions and is a major contribution to the global effort in tackling climate change," the statement said.
It added that China would face "enormous pressure and special difficulty in controlling greenhouse gas emissions".
The announcement marks the first time China has put specific numbers on a September pledge by President Hu Jintao to reduce the intensity of its carbon emissions as a percentage of economic growth by 2020.
Hu said at the time only that carbon intensity would be reduced by a "notable margin". However, emissions would continue to grow under China's plan.
Carbon intensity refers to emissions per unit of economic activity.
China's announcement came a day after Washington said President Barack Obama would attend the December 7-18 meeting in Copenhagen with an offer to cut US emissions by 17 percent from 2005 levels by 2020.
"This is definitely a very positive step China is taking just one week before Copenhagen," Yang Ailun, Greenpeace China's climate and energy campaign manager, told AFP. "But we think China can do more than this."
China earlier Thursday announced that Premier Wen Jiabao would join dozens of other world leaders at the summit, which was called to seek a successor to the Kyoto Protocol on limiting greenhouse gas emissions.
A foreign ministry spokesman said Wen's attendance would "fully demonstrate the great importance attached by the Chinese government to this issue".
Scientists have warned that without aggressive action, global temperatures could rise dramatically this century with calamitous consequences for world climate, leading to rising sea levels and other grave threats.
Pressure has mounted on China and the United States, the number one and two sources of carbon emissions, to announce substantive steps to limit their carbon emissions and seek a meaningful deal in Copenhagen.
Greenpeace's Yang said the United States had missed an opportunity to put "enormous pressure on China" by not announcing a more ambitious target.
Compared to the 1990 benchmark used by almost every other country, the US target only amounts to something like a four percent reduction from that year's levels, Yang said.
In contrast, the European Union has vowed to reduce its emissions by 20 percent from 1990 levels before 2020, raising the target to 30 percent in the event of an international agreement.
The US pledge, however, also promised steadily increased cuts to 2050, when emissions would be reduced by 83 percent from 2005 levels.
The United States has urged China to take aggressive steps to limit carbon emissions. But Beijing has argued that rich developed nations bear the historical responsibility for carbon build-up in the atmosphere and should shoulder the burden.
China says that as a developing nation, it should be given leeway on emissions as it seeks to grow its economy and alleviate poverty in the nation of 1.3 billion people.
China also has previously set goals of cutting energy consumption per unit of GDP by 20 percent between 2006 and 2010 and getting 10 percent of its power from renewable sources by 2010 and 15 percent by 2020.
Obama's offer reflects numbers in a bill narrowly passed by the House of Representatives in June but yet to be confirmed by the Senate.
A slightly more ambitious bill to come before the Senate early next year talks of a 20 percent reduction from 2005 levels by 2020.
Copenhagen climate change talks stall as CO2 emissions rise - Christian Science Monitor
jeudi, novembre 19, 2009, 09:15 AM - Développement durable
The Copenhagen summit on climate change is looking less likely to produce a binding CO2 emissions reduction agreement as a new study finds that global carbon dioxide emissions increased 29 percent in the past nine years.
Even as the Copenhagen climate change negotiations have moved into the slow lane, greenhouse gas emissions are accelerating, according to new evidence released today.
Negotiators at a preparatory meeting for the December climate summit said on Tuesday that firm commitments from the US and other industrial heavyweights to curb greenhouse gas emissions at the meeting are now looking unlikely. A binding global treaty on emissions was the initial aim of the conference.
Meanwhile, The Global Carbon Project, an international group of climate scientists, released research on Tuesday that found carbon-dioxide (CO2) emissions from power plants, factories, tree-felling and other human activities grew by 29 percent between 2000 and 2008 –a period in which leaders of major industrialized nations took the first fledgling steps to reduce their own emissions and make an international climate treaty work.
The Kyoto Protocol on combating climate change was passed in 1997 by over 180 nations with the intent of reducing global carbon emissions to a 1990 baseline. But in the intervening 12 years emissions have continued to rise, as country's have been unwilling to take the economic hits that reduced emissions are likely to require.
Political leaders are now looking to the US and President Barack Obama to take the lead on climate change, since the US is the second-largest carbon emitter after China. But legislation to curb US emissions is currently stalled in Congress, a factor that also makes broad success in Copenhagen less likely. Also uncertain is aid from the developed world to help poorer countries offset the economic hardships of converting to cleaner power sources.
"We still need more movement," said UN Climate Change head Yvo de Boer in Denmark on Tuesday. "Industrialized countries must raise their targets and financial commitments further... I look to the United States for a numerical mid-term target."
In recent weeks leaders in key countries have signalled that no one should look for a treaty to be approved in Copenhagen next month – a clear hope coming out of global climate talks in Bali in December 2007.
On Sunday Denmark's Prime Minister Lars Lokke Rasmussen suggested that countries aim for a more limited political agreement on reducing emissions and building a financial-aid regime for developing countries, with a legally-binding treaty put off until high-level talks in December 2010 in Mexico City. The UN's Mr. de Boer has said he prefers to see a legal document ready for approval in Bonn sometime in mid-2010.
Emissions up in recession
Despite the global economic slowdown last year, emissions rose 2 percent in 2008. The Global Carbon Project estimates that 2009's deep economic contraction trimmed global emissions by nearly 3 percent, but that short term dip is expected to reverse once recovery takes hold.
Noting that population growth and efforts to improve the standard of living in developing countries are among the underlying forces driving rising emissions, the need to cut CO2 emissions "is a very urgent task," says Taro Takahashi, a researcher at Columbia University's Lamont-Doherty Earth Observatory and one of the study's authors.
The question mark looming over the Copenhagen meeting has been the willingness of industrial nations to cap the increase in global average temperatures to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.
To stand an even chance of achieving that, countries should aim to stabilize atmospheric CO2 concentrations at between 350 and 400 parts per million, according to the Intergovernmental Panel on Climate Change. The Global Carbon Project's latest figures show that CO2 concentration levels have risen to 385 parts per million.
Moreover, the team estimates that where changes in land use, largely deforestation, accounted for 20 percent of human emissions between 1990 and 2000, that figure has fallen to about 12 percent for the 2000 to 2008 period. The emissions update appears in this week's issue of the journal Nature Geophysics.
Remaining uncertainty
No single study represents the final word on what's happening with carbon emissions. And the team acknowledges that more work needs to be done to cope with uncertainties. One key issue involves divvying up the uptake and release of CO2 among the various natural sources and "sinks." The study indicates that forests and oceans took up less CO2 during the 2000-2008 period than they did during the previous decade. They attribute the change to global warming and natural climate swings. Other researchers, however, point out that their work shows no change in the ability of these sinks to soak up CO2.
Still, because the Global Carbon Project was established to help inform political decisions on climate policies, its conclusions are likely to carry weight as negotiators grope their way toward a new climate treaty.
The list of outstanding issues is long, according to Jennifer Morgan, who heads the climate and energy program at the World Resources Institute in Washington. Convincing developed countries to make substantial emissions reductiover 180 nations with the intent of reducing global carbon emissions to a 1990 baseline. But in the intervening 12 years emissions have continued to rise, as country's have been unwilling to take the economic hits that reduced emissions are likely to require.
Political leaders are now looking to the US and President Barack Obama to take the lead on climate change, since the US is the second-largest carbon emitter after China. But legislation to curb US emissions is currently stalled in Congress, a factor that also makes broad success in Copenhagen less likely. Also uncertain is aid from the developed world to help poorer countries offset the economic hardships of converting to cleaner power sources.
"We still need more movement," said UN Climate Change head Yvo de Boer in Denmark on Tuesday. "Industrialized countries must raise their targets and financial commitments further... I look to the United States for a numerical mid-term target."
In recent weeks leaders in key countries have signalled that no one should look for a treaty to be approved in Copenhagen next month – a clear hope coming out of global climate talks in Bali in December 2007.
On Sunday Denmark's Prime Minister Lars Lokke Rasmussen suggested that countries aim for a more limited political agreement on reducing emissions and building a financial-aid regime for developing countries, with a legally-binding treaty put off until high-level talks in December 2010 in Mexico City. The UN's Mr. de Boer has said he prefers to see a legal document ready for approval in Bonn sometime in mid-2010.
Emissions up in recession
Despite the global economic slowdown last year, emissions rose 2 percent in 2008. The Global Carbon Project estimates that 2009's deep economic contraction trimmed global emissions by nearly 3 percent, but that short term dip is expected to reverse once recovery takes hold.
Noting that population growth and efforts to improve the standard of living in developing countries are among the underlying forces driving rising emissions, the need to cut CO2 emissions "is a very urgent task," says Taro Takahashi, a researcher at Columbia University's Lamont-Doherty Earth Observatory and one of the study's authors.
The question mark looming over the Copenhagen meeting has been the willingness of industrial nations to cap the increase in global average temperatures to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.
To stand an even chance of achieving that, countries should aim to stabilize atmospheric CO2 concentrations at between 350 and 400 parts per million, according to the Intergovernmental Panel on Climate Change. The Global Carbon Project's latest figures show that CO2 concentration levels have risen to 385 parts per million.
Moreover, the team estimates that where changes in land use, largely deforestation, accounted for 20 percent of human emissions between 1990 and 2000, that figure has fallen to about 12 percent for the 2000 to 2008 period. The emissions update appears in this week's issue of the journal Nature Geophysics.
Remaining uncertainty
No single study represents the final word on what's happening with carbon emissions. And the team acknowledges that more work needs to be done to cope with uncertainties. One key issue involves divvying up the uptake and release ofCO2 among the various natural sources and "sinks." The study indicates that forests and oceans took up less CO2 during the 2000-2008 period than they did during the previous decade. They attribute the change to global warming and natural climate swings. Other researchers, however, point out that their work shows no change in the ability of these sinks to soak up CO2.
Still, because the Global Carbon Project was established to help inform political decisions on climate policies, its conclusions are likely to carry weight as negotiators grope their way toward a new climate treaty.
The list of outstanding issues is long, according to Jennifer Morgan, who heads the climate and energy program at the World Resources Institute in Washington. Convincing developed countries to make substantial emissions reduction is just one challenge. Convincing major developing countries to slow and eventually reverse their emissions trends is another, as is the need to provide financial aid to poorer countries to buy the technology needed to achieve goals they agree to. Finally, finding a monitoring regime and legal status for enforcement that all countries will accept won't be easy,
"All the major economies coming to Copenhagen are coming ready to fill in those blanks," says Ms. Morgan. These countries are looking for "what the [Obama] administration is able to bring to the table consistent with what Congress is debating" in energy and climate bills it's currently considering.
Yet President Obama, during a summit with Chinese leaders this week, noted that "our aim ... is not a partial accord or a political declaration, but rather an accord that covers all of the issues in the negotiations and one that has immediate operational effect."
Some analysts who have been watching this process since the Kyoto Protocol was hammered out still say much can be accomplished at Copenhagen, even if the result falls short of a legally binding agreement for now.
"A few months before Kyoto, people were throwing up their hands saying nothing could happen. A month before Rio, in the final negotiating session, it was unclear there would be the political will to move an agreement forward for the heads of state," says Alden Meyer, director of strategy and policy for the Union of Concerned Scientists in Washington. "Some of us have seen this movie before. Expectations are high and they should be kept high."
WASHINGTON (Reuters) - The Environmental Protection Agency on Monday cleared the way for regulation of greenhouse gases without new laws passed by Congress, reflecting President Barack Obama's commitment to act on climate change as a major summit opened in Copenhagen.
The EPA ruling that greenhouse gases endanger human health, widely expected after it issued a preliminary finding earlier this year, will allow the agency to regulate planet-warming gases even without legislation in Congress.
The agency could begin to make rules as soon as next year to regulate emissions from vehicle tailpipes, power utilities and heavy industry under existing laws.
Obama and his Democratic allies in Congress will still pursue legislation in Congress, which has been slow to act. But the EPA move gave a timely push to the president's aims of securing short-term limits to harmful emissions.
It was expected to inject some optimism into the two-week United Nations meeting in Copenhagen, which Obama is due to attend next week, but was criticized by some U.S. business groups who fear it could push up costs.
"EPA has finalized its endangerment finding on greenhouse gas pollution and is now authorized and obligated to make reasonable efforts to reduce greenhouse pollutants," said Lisa Jackson, the EPA administrator. "This administration will not ignore science or the law any longer."
The Supreme Court ruled in 2007 that the EPA had the right to regulate emissions of the gases under the Clean Air Act. But under the administration of former President George W. Bush, the EPA said Congress was the right place to frame action.
Business groups said the EPA announcement would hurt the economy and endanger jobs just as the country emerges from a deep recession.
Legislation by Congress would be more palatable politically for Obama, because it would represent a compromise between business, politicians and other interests rather than through an imposed ruling.
STRONGER HAND IN COPENHAGEN
The EPA ruling applies to six gases scientists say contribute to global warming, including the main one, carbon dioxide.
There had been fears that Obama, who has made fighting climate change one of his priorities, would arrive almost empty handed at the U.N. conference because climate legislation has stalled in Congress.
"The EPA move strengthens Obama's hand at Copenhagen," said Joe Mendelson, global warming policy director at the National Wildlife Federation. "It gives him additional authority that if Congress doesn't pass climate legislation, the agency can put the country on the path to meet his climate goals."
Obama will pledge at Copenhagen that the United States, the world's second largest emitter of greenhouse gases, will cut emissions by roughly 17 percent by 2020 from 2005 levels.
World leaders hope to reach an agreement at the meeting on getting rich and developing countries to share the burden in fighting climate change.
The climate bill has been delayed in the U.S. Senate by a debate over a sweeping reform of healthcare, but lawmakers hope to pass a bill in the spring. Climate legislation passed narrowly in the House of Representatives in June.
The Obama administration has always said it prefers legislation over action by the EPA.
CONGRESSIONAL ACTION
If the EPA acts alone it could face a slew of legal challenges, including from business groups who say the action would overstep the administration's authority, as well as from environmentalists who seek stronger steps.
But the administration had pressed the EPA to prod business to support efforts in Congress, and to show the world Washington is committed to fighting climate change.
Democratic Senator John Kerry said the EPA move was meant to spur Congress to act. But he said "imposed regulations by definition will not include the job protections and investment incentives we are proposing in the Senate today."
Republicans said the move was equivalent to imposing an energy tax. "By seeking to sharply curtail carbon dioxide (and thus energy usage), the EPA is in effect working to decrease economic activity," the Republican Study Committee said.
One business group was quick to criticize the EPA.
Keith McCoy, vice president of energy policy at the National Association of Manufacturers said the EPA was moving forward with an agenda that will put additional burdens on manufacturers, cost jobs and drive up the price of energy."
The EPA decision, which now will be open for public review, does not preclude legislation. Any new regulations could take a long time to implement, giving Congress room to act.
Still, big industry could learn about changes soon. Jackson said car makers will know by the end of March about required increases in fuel economy standards for cars built for the 2012 model year.
"All industries will be called upon to reduce carbon emissions," said Dave McCurdy, chief executive of the Alliance of Automobile Manufacturers.
An administration proposal unveiled in September would require a boost fuel efficiency by 40 percent by 2016 and aim to cut carbon emissions by 21 percent by 2030. (Additional reporting by Ayesha Rascoe, Roberta Rampton, Deborah Zabarenko, Tom Doggett, Tom Ferraro in Washington and Richard Cowan in Copenhagen; Editing by Simon Denyer and Chris Wilson)
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vendredi 4 décembre 2009
co2 refrigeration
NEW HEAT RECOVERY AND DEFROST METHODS FOR SUPERMARKET
MULTIPLEX REFRIGERATION SYSTEMS
VASILE MINEA
LTEE (Hydro-Quebec), Shawinigan, Canada
SERGE DUBÉ
RSD Réfrigération Inc., Vaudreuil - Dorion (Québec), Canada
JORDAN KANTCHEV
Systèmes LMP Inc., Laval (Québec), Canada
Summary
Two high-efficiency multiplex supermarket refrigeration systems with total heat reclaim
capability, and a high-speed defrost system are presented. The first heat reclaim system [1]
involves directional and modulating valves to communicate the superheated vapour to the aircooled
condensers or to the heat reclaim coils, and to adjust the pressure according to the outside
temperature. A refrigerant reservoir receives liquid from both condensers and heat reclaim coils,
and a sub-cooling heat exchanger with a by-pass and a special expansion valve is also provided.
In the second heat reclaim system [2], heat pumps are installed on the discharge line of a
refrigeration system with floating head pressure to recover the total heat and to provide comfort
heating of the building during the cold periods of the year. When no heat reclaim is required, the
heat pump system is used for air conditioning and sub-cooling purposes. The high-speed defrost
system [3] mainly involves an auxiliary reservoir that operates at low pressure and is
automatically flushed into the main reservoir when liquid refrigerant accumulates to a
predetermined level. It creates a pressure differential across the evaporators, sufficient to perform
quickly defrost cycles, even at low compressor head pressures. The experimental evaluation of
the mentioned innovations will be completed during the next dominated heating season, notably
in order to demonstrate their energy performances in a cold climate, comparatively with those of
a conventional system, also instrumented.
1. Introduction
The purpose of the refrigeration system in a supermarket is to provide cooling to the refrigerated
display cases and walk-in boxes. In cold climates, the major contribution of the electric energy
use and demand comes from the refrigeration system (around 50 %). In fact, almost 100 % of the
supermarkets are there still constructed with that type of equipment. The compressors, generally
of the semi-hermetic type, are located in a machine room, normally on mezzanine, and mounted
on racks with all necessary piping, valves, and electrical components needed for the operation
and control. Remote air-cooled or evaporative condensers used in conjunction with multiple
compressors are usually installed on the roof, and all refrigerated fixtures employ directexpansion
refrigerant-air coils. The multiplexed compressors allow to continuously matching
their capacity with the refrigeration load, and so to operate at low head pressure. The capacity
control strategy commonly uses suction pressure set points, digital stepping strategy to select the
compressor combination to be operated, and cylinder unloading. The purpose is to maintain a
2
tight suction pressure control band, which results in operation at a higher average suction
pressure. The minimum condensing temperature setting recommended by most manufacturers is
21 °C (70 °F). Hot gas defrost is normally controlled by a time clock or by demand defrost based
upon actual case requirements. Liquid sub-cooling, performed by ambient or mechanical devices,
or external liquid-suction heat exchangers, increases refrigeration capacity as well as prevents
the formation of flash gas during low head pressure operation. A new technology (“liquid
delivery system”), already employed in Canada, allows to the refrigeration system to work with
floating condensing pressure depending on the ambient air temperature. This is achieved by
installing a centrifugal pump on the line of liquid thus providing the necessary pressure
differential for the proper operation of the expansion valve and reducing the condensing
temperature up to 10 °C (50 °F), depending on ambient air temperature. This technology could
produce energy savings up to 35 % of the total energy cost, but it creates difficulties in the field
of heat reclaim because the air to be heated is warmer then the refrigerant to be cooled. When a
heat reclaim is required, the condensing pressure has to be raised artificially in order to achieve
proper heat transfer, thus losing the benefits of the liquid delivery system. The majority of
supermarkets in Canada take advantage of the large amount of heat rejected through the
refrigeration system by using this heat for space or water heating. Generally, when space heat is
called for, a three-way valve is activated, directing the refrigerant discharge to a heat reclaim coil
located in the central air handler. The refrigerant then passes to the condenser where any
remaining condensing of the refrigerant occurs. Control of heat reclaim is normally handled
through a two-stage thermostat which allows to recover between approximately 20 % and 50 %
of total heat rejection during a full or partial condensing. The condenser is flooded by the use of
a liquid holdback valve, raising the condensing temperature to the desired value, usually to 35 °C
(95 °F).
During the last few years, two of the most innovating refrigeration contractors have done several
improvements of their traditional multiplexed systems that are still largely employed in Canada.
These improvements concern notably the heat recovery and defrost cycle optimisation. The first
objective was to satisfy up to 100 % the space heating needs with heat reclaim, thus eliminating
the use of natural gas or other fossil combustibles for heating. The second objective was to
reduce the defrost cycle’s length in order to improve the quality of foodstuff and, simultaneously.
9. The method according to claim 8, wherein monitoring detection data comprises monitoring a temperature in the drain/drain basin of the refrigerated enclosure, and identifying a build-up condition comprises comparing the temperature with at least one predetermined temperature value.
10. The method according to claim 9, wherein comparing the temperature with at least one predetermined temperature value comprises determining that the temperature is above/below the at least one predetermined temperature value for said given time period.
11. The method according to claim 9, wherein comparing the temperature with at least one predetermined temperature value comprises determining that the temperature is outside a selected range of temperature values for said given time period.
12. The method according to claim 8, further comprising pausing the monitoring of detection data for a maintenance period.
13. The method according to claim 12, wherein pausing for a maintenance period comprises pausing during a defrost cycle of a refrigerated enclosure.
14. The method according to claim 8, wherein monitoring detection data comprises visually monitoring the drain/drain basin of the refrigerated enclosure, and identifying a build-up condition comprises comparing a visual monitoring signal with an unobstructed signal value.
15. The method according to claim 8, wherein indicating the requirement for an intervention comprises alarming off-site personnel.
16. The method according to claim 8, wherein monitoring detection data comprises monitoring a temperature in the drain/drain basin of the refrigerated enclosure, and identifying a build-up condition comprises comparing a variation of the temperature over the time period with an acceptable temperature variation value.
Description:
CROSS-REFERENCE TO RELATED APPLICATION
, ventilation, déshumidification, chauffage et de contrôle.
En entrevue au JOURNAL, le président du Groupe CSC, Serge Dubé, a mentionné que l'Eco-System va permettre de réduire de façon importante les gaz à effet de serre dans l'environnement avec l'élimination du réfrigérant synthétique.
Il a indiqué qu'un kilo de réfrigérant synthétique rejette 3,5 tonnes de CO2 dans l'atmosphère. «Dans les gros supermarchés, il se perd 300 kilos de réfrigérant par année», révèle M. Dubé.
Pour parvenir à commercialiser le produit, ce dernier a dû consacrer beaucoup de temps, de recherches et d'énergie. Une quinzaine d'années ont été nécessaires mettre au point un tel frigo tout aussi efficace.
«Depuis 1994, on travaille pour réduire les pertes de réfrigérant et pour améliorer les coûts de chauffage. Il était également important d'améliorer la qualité du produit et le rendement de la machine de réfrigération. L'Eco-System va faire tout en un, soit le contrôle de gestion du bâtiment», explique Serge Dubé.
Pour y parvenir, le grand manitou du Groupe CSC a effectué des séjours en Chine, Australie, Allemagne et Italie pour aller chercher les meilleures connaissances technologiques dans ce domaine de pointe bien précis.
«J'ai travaillé avec les meilleurs au monde en technologie pour voir ce qui se faisait ailleurs. J'ai pris ce qu'il y avait de bon pour l'environnement, la climatisation, le contrôle et le chauffage. On peut faire d'énormes progrès pour la planète. Les gens sont plus conscients de l'environnement que par le passé», a fait remarquer M. Dubé.
Magasin laboratoire
Le Groupe CSC a loué des locaux dans le but de simuler un magasin de 25 000 pieds carrés afin d'étudier si l'Eco-System répond aux attentes. Il s'agit en fait d'un magasin laboratoire comportant des frigos.
«Depuis un an, nous avons fait des essais, des améliorations et nous avons réglé des problèmes. Les résultats sont positifs», explique Serge Dubé.
Ainsi, les supermarchés équipés de l'Éco-System verront leurs coûts d'exploitation et d'entretien diminués de façon significative puisque la consommation d'énergie est réduite au minimum, si l'on se fie à M. Dubé.
En plus, il affirme que le système élimine pratiquement les coûts reliés au chauffage puisque la récupération de chaleur permet souvent de chauffer la totalité du magasin. Les frais d'entretien seraient moins coûteux de 30 %.
Le nouveau système de réfrigération permettra de garder les aliments plus longtemps, ce qui occasionnera moins de pertes pour les détaillants. Il y a donc des économies à faire sur la qualité des produits et le service après-vente.
Environ 20 personnes travaillent uniquement sur ce projet, que ce soit pour la mise en marché, les améliorations, le branchement et autres.
L'Eco-System pourra être adapté à la taille des supermarchés. «Il n'y a aucune limite quant aux produits qui peuvent être réfrigérés», estime M. Dubé. Depuis 1994, c'est un montant de 4 millions $ qui a été investi pour ce projet spécifique.
Magasins intéressés
Il va sans dire que Serge Dubé fonde de grands espoirs sur l'Eco-System qui sera commercialisé prochainement.
D'ailleurs, certains magasins se sont montrés intéressés à acquérir cette nouvelle technologie dont le nouveau IGA à Coteau-du-Lac qui devrait ouvrir ses portes dans les prochaines semaines.
D'autres ententes ont été signées avec d'importantes chaînes d'alimentation, dont des marchés IGA et Metro à Laval, Québec et Cookshire dans les Cantons de l'Est.
C'est la compagnie Réfrigération S. Dubé, une division du Groupe CSC, qui installe le système et effectuera le service après-vente.
Le coût unitaire de chaque Eco-System variera entre 200 000 $ et 1 million $ selon la taille du magasin. «Ça va être du cas par cas», signifie M. Dubé.
«Nous allons rencontrer les chaînes spécialisées. Le prochain mois s'avère une étape cruciale. D'ici la fin de l'année, il y aura une dizaine d'Eco-System en opération», soutient le président.
Le marché canadien compte à lui seul, près de 6500 détaillants en alimentation. Si tout va bien, M. Dubé estime que le chiffres d'affaires du Groupe CSC pourrait passer de 20 millions $ à 100 millions $ d'ici les cinq prochaines années.
Pour répondre à la demande, l'entreprise compte investir 1 million $ et agrandir ses installations de 20 000 pieds carrés aménagées en 2007 sur la rue Royal. «Si tout fonctionne comme prévu, il y aura un ajout éventuel de 15 000 pieds pour un total de 35 000 pieds carrés», révèle Serge Dubé.
Le nombre d'emplois devrait doubler. Une trentaine de personnes oeuvrent actuellement à l'usine des Coteaux et l'on prévoit engager 30 autres employés. Globalement, le Groupe CSC emploie 130 personnes un peu partout à travers la province au sein de diverses divisions.
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