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Refrigerants for Commercial Refrigeration Applications

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Refrigerants for Commercial Refrigeration Applications Refrigerants for commercial refrigeration applications June 2011 22005ECT-162005ECT-162 RR6.indd6.indd 1 66/22/2011/22/2011 99:03:17:03:17 AAMM Contents Research has shown that properly designed and maintained systems using HFC refrigerants provide the lowest GWP and Executive summary ........................ 2 zero ozone depletion. They are also a safe and cost-effective Introduction and background ........................ 2 solution that will serve us well into the future. Environmental drivers ........................ 3 Regulations and timing ........................ 5 In this paper, the long-term, non-ozone-depleting replace- Criteria for refrigerant selection ........................6 ments for hydrochlorofluorocarbon (HCFC) R-22 are also discussed. The experience to date shows that these alterna- Chlorine-free refrigerants (HFCs) ........................ 7 tives, when used in optimized systems, provide performance Halogen-free refrigerants ....................... 11 superior to the baseline HCFC refrigerant. Other refrigerant System design considerations ....................... 12 choices, such as carbon dioxide and hydrocarbons, are also Service considerations ....................... 14 discussed, along with their relative merits to HFCs. Future direction .......................15 Emerson Climate Technologies is committed to providing Glossary of terms ....................... 16 solutions that improve human comfort, safeguard food and Appendix ....................... 17 protect the environment. We recognize that this is a difficult Executive summary balance, but remain optimistic. We are confident that we can develop solutions that provide efficient commercial refrig- The refrigeration industry has supported global efforts to eration without compromising our global environment. The protect the environment by phasing out chlorine-containing following paper discusses the factors that we feel are most refrigerants in accordance with the Montreal Protocol. These important for meeting this challenge. actions have significantly cut chlorine in the atmosphere and are starting to repair the ozone layer. DISCLAIMER Use only refrigerants and lubricants approved by and Today, there is more attention on climate change and in the manner prescribed by Emerson. In some circum- reducing greenhouse gases. Carbon dioxide is by far the most stances, non-approved refrigerants and lubricants may be significant greenhouse gas, produced mainly by burning fossil dangerous and could cause fires, explosions or electrical fuels for electrical generation and transportation. Since refrig- shorting. For more information, contact Emerson and your eration equipment consumes energy, energy-efficient designs original equipment manufacturer (OEM). are important to reducing carbon dioxide production. If refrigerant gas escapes from a system, it can also contrib- Introduction and background ute to direct global warming. System manufacturers and Scientific data supports the hypothesis that chlorine from re- contractors are working hard to contain refrigerant leaks. frigerants has depleted the earth’s ozone layer and is linked to a rise in skin-related diseases1. The air conditioning and For a refrigerant to be considered a long-term option it must refrigeration industry has supported global efforts to protect meet three criteria — it must be safe; it must be environmen- the environment by introducing non-chlorine-containing tally friendly; and it must provide excellent performance refrigerants. The Montreal Protocol, established in 1987 benefits — thus resulting in zero ozone depletion with low Global Warming Potential (GWP). and later revised, provides guidelines for individual country legislation, setting timetables for the phase-out of chlorine- Several non-halogen substances, including ammonia, carbon containing refrigerants. Today, 196 nations have become dioxide and hydrocarbons, will also work as refrigerants. All party to the Montreal Protocol. these substances can be refrigerants for the right application if the system can be designed to meet key selection crite- The effort started with an emphasis on cutting chlorofluoro- ria. Component and equipment manufacturers continue to carbon (CFC) refrigerants. Work in the late 1980s and early research how these refrigerants perform in systems. 1990s centered on eliminating CFCs which were used in foam blowing, cleaning and refrigeration applications and Hydrofluorocarbons (HFCs) are non-ozone-depleting, non- centrifugal chillers for air conditioning. By the end of 1995, flammable, recyclable and energy-efficient refrigerants of developed countries stopped producing CFCs, and they are low toxicity that are used safely worldwide. Although HFCs no longer used in new equipment today. These actions have are the best environmental and economic choice today, the significantly reduced atmospheric chlorine and are starting global sustainability of HFCs requires a focus by the industry to repair the ozone layer. on refrigerant containment and energy efficiency. 2 22005ECT-162005ECT-162 RR6.indd6.indd 2 66/22/2011/22/2011 99:03:48:03:48 AAMM In 1997 the Kyoto Protocol, signed and ratified by many sun. Depleted ozone allows more ultraviolet light to reach nations around the world, focused attention on the impact the surface, negatively affecting the quality of human, plant, of human activity on climate change. As a result, there is animal and marine life. now more attention on global warming. Although the Kyoto Scientific data verifies that the earth’s ozone layer has been Protocol does not apply to the United States, our industry has depleted. The data also verify that a major contribution to worked to lower the impact of refrigerants on climate change ozone depletion is chlorine, much of which has come from with higher-efficiency refrigerants and system designs. the CFCs used in refrigerants and cleaning agents. In 1997 the Air-Conditioning and Refrigeration Institute (ARI) Research has shown that even the chlorine found in R-22 finished a major international testing program entitled the refrigerants can be harmful to the ozone layer. The need to Alternative Refrigerants Evaluation Program (AREP). The protect the earth’s ozone has resulted in new government AREP report indentified several suitable HFC replacements regulations and HFC refrigerants. Since HFCs are chlorine for HCFC R-22. In the USA and Europe, these HFC replace- free, they will not damage the ozone layer. ments are already being widely used. Some of these replace- ment refrigerants have different operating characteristics Climate Change than HCFC R-22, but they all eliminate chlorine and potential According to the National Academy of Scientists, the tem- ozone depletion, leaving climate change as the focus for perature of the earth’s surface has risen by about one degree future regulations and control. Fahrenheit (0.5 degree Kelvin) in the past century2. There is Environmental drivers evidence that suggests that much of the warming during the last 50 years is because of greenhouse gases, many of which There are two factors important to the discussion of the are the by-product of human activities. Greenhouse gases environmental impact of refrigerants: ozone depletion and include water vapor, carbon dioxide, methane and nitrous global warming. oxide, and some refrigerants. When these gases build up in Ozone depletion the atmosphere, they trap heat. The natural greenhouse ef- fect is needed for life on earth, but scientists believe that too The ozone layer surrounding the earth is a reactive form of much greenhouse effect will lead to climate change. Figure 1 oxygen 25 miles above the surface. It is essential for planetary shows the mechanism of this global warming process. life, as it filters out dangerous ultraviolet light rays from the The greenhouse effect Some of the infrared radiation passes through the atmosphere, and some is absorbed and re-emitted in all directions by greenhouse gas molecules. The effect of this is to warm the earth’s surface and lower atmosphere. Some solar radiation is reflected Infrared radiation Solar radiation by the earth and the atmosphere. is emitted from passes through the the earth’s surface. clear atmosphere. Most radiation is absorbed by the earth’s surface and warms it. Figure 1 3 22005ECT-162005ECT-162 RR6.indd6.indd 3 66/22/2011/22/2011 99:03:49:03:49 AAMM Carbon dioxide (CO2) is one of the major greenhouse gases. power used. Higher energy efficiency of some refrigerants Vegetation is the primary generator of CO2, along with natu- can lower the indirect effect and offset a somewhat higher ral organic materials decomposing. GWP. Burning fossil fuels also adds CO2 to the atmosphere. Fossil Direct global warming is an issue only if the refrigerant leaks fuels are used in power plants around the world to produce or is released from the refrigeration system; thus, refrigerant electricity for vital social needs. According to the U.S. Energy containment in the system is the key to cutting the direct Information Administration, nearly 30 billion metric tons global warming effect. The best way to do this is with low- of energy-related carbon dioxide were produced in 20073. charge system designs, the quick repair of all leaks and the In comparison, total annual HFC production globally is less recovery of refrigerant during service operations. than 0.001 percent of this figure. It is estimated that HFCs Indirect global warming is a function of the efficiency of any will contribute no more than three percent of greenhouse
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