1、29.1CHAPTER 29 REFRIGERANTSRefrigerant Properties 29.1Refrigerant Performance 29.8Safety . 29.9Leak Detection 29.9Compatibility with Construction Materials 29.9EFRIGERANTS are the working fluids in refrigeration, air-R conditioning, and heat-pumping systems. They absorb heat fromone area, such as an
2、 air-conditioned space, and reject it into another,such as outdoors, usually through evaporation and condensation,respectively. These phase changes occur both in absorption andmechanical vapor compression systems, but not in systems operatingon a gas cycle using a fluid such as air. (See Chapter 2 f
3、or more infor-mation on refrigeration cycles.) The design of the refrigeration equip-ment depends strongly on the selected refrigerants properties. Tables1 and 2 list standard refrigerant designations, some properties, andsafety classifications from ASHRAE Standard 34.Refrigerant selection involves
4、compromises between conflictingdesirable thermophysical properties. A refrigerant must satisfy manyrequirements, some of which do not directly relate to its ability totransfer heat. Chemical stability under conditions of use is an essentialcharacteristic. Safety codes may require a nonflammable refr
5、igerantof low toxicity for some applications. Environmental consequences ofrefrigerant leaks must also be considered. Cost, availability, effi-ciency, compatibility with compressor lubricants and equipmentmaterials, and local and national regulations are other concerns.Latent heat of vaporization is
6、 another important property. On amolar basis, fluids with similar boiling points have almost the samelatent heat. Because compressor displacement is defined on a volu-metric basis, refrigerants with similar boiling points produce similarrefrigeration effect with a given compressor. On a mass basis,
7、latentheat varies widely among fluids. Efficiency of a theoretical vaporcompression cycle is maximized by fluids with low vapor heatcapacity. This property is associated with fluids having a simplemolecular structure and low molecular mass.Transport properties (e.g., thermal conductivity and viscosi
8、ty)affect performance of heat exchangers and piping. High thermalconductivity and low viscosity are desirable.No single fluid satisfies all the attributes desired of a refrigerant;consequently, various refrigerants are used. This chapter describesthe basic characteristics of various refrigerants, an
9、d Chapter 30 liststhermophysical properties.REFRIGERANT PROPERTIESGlobal Environmental PropertiesChlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) can affect both stratospheric ozone and climate change,whereas hydrofluorocarbons (HFCs) can affect climate change.Minimizing all refrigeran
10、t releases from systems is important notonly because of environmental impacts, but also because chargelosses lead to insufficient system charge levels, which in turn resultsin suboptimal operation and lowered efficiency.Stratospheric Ozone Depletion. The stratospheric ozone layerfilters out the UV-B
11、 portion of the suns ultraviolet (UV) radiation.Overexposure to this radiation increases the risk of skin cancer,cataracts, and impaired immune systems. It also can damage sensi-tive crops, reduce crop yields, and stress marine phytoplankton (andthus human food supplies from the oceans). In addition
12、, exposure toUV radiation degrades plastics and wood.Stratospheric ozone depletion has been linked to the presence ofchlorine and bromine in the stratosphere. Chemicals with long atmo-spheric lifetimes can migrate to the stratosphere, where the mole-cules break down from interaction with ultraviolet
13、 light or throughchemical reaction. Chemicals such as CFCs and HCFCs releasechlorine, which reacts with stratospheric ozone.Ozone-depleting substances, including CFCs and HCFCs, are to bephased out of production under the Montreal Protocol (UNEP 2009).In the United States, production and importation
14、 of CFCs were bannedcompletely in 1996. HCFCs are being phased down, with completephaseout set for 2030. In 2010, to meet the Montreal Protocol phase-down schedule, U.S. regulations banned production and importationof HCFC-142b and HCFC-22 for use in new equipment. ReclaimedCFC and HCFC refrigerants
15、 that meet the requirements of AHRIStandard 700 can continue to be used for servicing existing systems.A complete list of U.S. regulations for CFC and HCFC refrigerants,including phaseout schedules, may be found at http:/www.epa.gov/ozone/strathome.html. Phaseout schedules for CFCs and HCFCs forboth
16、 developed and developing countries are summarized on theOzone Secretariat web site at http:/ozone.unmfs.org/new_site/en/Treaties/control_measures_summary.php.Global Climate Change. The average global temperature isdetermined by the balance of energy from the sun heating the earthand its atmosphere
17、and of energy radiated from the earth and theatmosphere to space. Greenhouse gases (GHGs), such as CO2andwater vapor, as well as small particles trap heat at and near the sur-face, maintaining the average temperature of the Earths surfaceabout 61F warmer than would be the case if these gases and par
18、ti-cles were not present (the greenhouse effect).Global warming (also called global climate change) is a concernbecause of an increase in the greenhouse effect from increasing con-centrations of GHGs attributed to human activities. The major GHG ofconcern is CO2released to the atmosphere when fossil
19、 fuels (coal, oil,and natural gas) are burned for energy. Methane (CH4), nitrous oxide(N2O), CFCs, HCFCs, HFCs, hydrofluoroethers (HFEs), hydrofluo-roolefins (HFOs), perfluorocarbons (PFCs), nitrogen trifluoride(NF3), and sulfur hexafluoride (SF6) are also GHGs.In 1988, the United Nations Environmen
20、t Programme (UNEP)and the World Meteorological Organization (WMO) established theIntergovernmental Panel on Climate Change (IPCC) to provide anobjective source of information about the causes of climate change,its potential environmental and socioeconomic consequences, andthe adaptation and mitigati
21、on options to respond to it. According toIPCC (2007a), atmospheric concentration of carbon dioxide hasincreased by more than 35% over the past 250 years, primarily fromburning fossil fuels, with some contribution from deforestation.Concentration of methane has increased by over 145%, and nitrousoxid
22、e by about 18%. IPCC (2007a) deems atmospheric concentra-tions of fluorochemicals, including fluorocarbon gases (CFCs,The preparation of this chapter is assigned to TC 3.1, Refrigerants andSecondary Coolants.29.2 2013 ASHRAE HandbookFundamentalsTable 1 Refrigerant Data and Safety ClassificationsRefr
23、igerant Number Chemical Namea,bChemical FormulaaMolecularMassaNormal Boiling Point,aFSafetyGroupMethane Series11 Trichlorofluoromethane CCl3F 137.4 75 A112 Dichlorodifluoromethane CCl2F2120.9 22 A112B1 Bromochlorodifluoromethane CBrClF2165.4 2513 Chlorotrifluoromethane CClF3104.5 115 A113B1 Bromotri
24、fluoromethane CBrF3148.9 72 A114 Tetrafluoromethane (carbon tetrafluoride) CF488.0 198 A121 Dichlorofluoromethane CHCl2F 102.9 48 B122 Chlorodifluoromethane CHClF286.5 41 A123 Trifluoromethane CHF370.0 116 A130 Dichloromethane (methylene chloride) CH2Cl284.9 104 B231 Chlorofluoromethane CH2ClF 68.5
25、1632 Difluoromethane (methylene fluoride) CH2F252.0 62 A2L40 Chloromethane (methyl chloride) CH3Cl 50.4 12 B241 Fluoromethane (methyl fluoride) CH3F 34.0 10950 Methane CH416.0 259 A3Ethane Series113 1,1,2-trichloro-1,2,2-trifluoroethane CCl2FCClF2187.4 118 A1114 1,2-dichloro-1,1,2,2-tetrafluoroethan
26、e CClF2CClF2170.9 38 A1115 Chloropentafluoroethane CClF2CF3154.5 38 A1116 Hexafluoroethane CF3CF3138.0 109 A1123 2,2-dichloro-1,1,1-trifluoroethane CHCl2CF3153.0 81 B1124 2-chloro-1,1,1,2-tetrafluoroethane CHClFCF3136.5 10 A1125 Pentafluoroethane CHF2CF3120.0 55 A1134a 1,1,1,2-tetrafluoroethane CH2F
27、CF3102.0 15 A1141b 1,1-dichloro-1-fluoroethane CH3CCl2F 117.0 90142b 1-chloro-1,1-difluoroethane CH3CClF2100.5 14 A2143a 1,1,1-trifluoroethane CH3CF384.0 53 A2L152a 1,1-difluoroethane CH3CHF266.0 11 A2170 Ethane CH3CH330.0 128 A3EthersE170 Dimethyl ether CH3OCH346.0 13 A3Propane Series218 Octafluoro
28、propane CF3CF2CF3188.0 35 A1227ea 1,1,1,2,3,3,3-heptafluoropropane CF3CHFCF3170.0 3 A1236fa 1,1,1,3,3,3-hexafluoropropane CF3CH2CF3152.0 29 A1245fa 1,1,1,3,3-pentafluoropropane CF3CH2CHF2134.0 59 B1290 Propane CH3CH2CH344.0 44 A3Cyclic Organic Compounds (see Table 2 for blends)C318 Octafluorocyclobu
29、tane (CF2)4 200.0 21 A1Miscellaneous Organic CompoundsHydrocarbons600 Butane CH3CH2CH2CH358.1 31 A3600a 2-methylpropane (isobutane) CH(CH3)2CH358.1 11 A3601 Pentane CH3(CH2)3CH372.15 97 A3601a 2-methylbutane (isopentane) (CH3)2CHCH2CH372.15 82 A3Oxygen Compounds610 Ethyl ether CH3CH2OCH2CH374.1 9461
30、1 Methyl formate HCOOCH360.0 89 B2Sulfur Compounds620 (Reserved for future assignment)Nitrogen Compounds630 Methanamine (methyl amine) CH3NH231.1 20631 Ethanamine (ethyl amine) CH3CH2(NH2)45.1 62Refrigerants 29.3Inorganic Compounds702 Hydrogen H22.0 423 A3704 Helium He 4.0 452 A1717 Ammonia NH317.0
31、28 B2L718 Water H2O18.21A1720 Neon Ne 20.2 411 A1728 Nitrogen N228.1 320 A1732 Oxygen O232.0 297740 Argon Ar 39.9 303 A1744 Carbon dioxide CO244.0 109cA1744A Nitrous oxide N2O 44.0 129764 Sulfur dioxide SO264.1 14 B1Unsaturated Organic Compounds1150 Ethene (ethylene) CH2=CH228.1 155 A31234yf 2,3,3,3
32、-tetrafluoro-1-propene CF3CF=CH2114.0 20.9 A2L1234ze(E) Trans-1,3,3,3-tetrafluoro-1-propene CF3CH=CHF 114.0 2.2 A2L1270 Propene (propylene) CH3CH=CH242.1 54 A3Source: ANSI/ASHRAE Standard 34-2010.aChemical name, chemical formula, molecular mass, and normal boiling point are notpart of this standard.
33、bPreferred chemical name is followed by the popular name in parentheses.cSublimes.Table 2 Data and Safety Classifications for Refrigerant BlendsRefrig-erant No. Composition (Mass %) Composition TolerancesMolec-ular MassaNormal Bubble Point, FNormal Dew Point, FSafety GroupZeotropes400 R-12/114 (must
34、 be specified) A1401A R-22/152a/124 (53.0/13.0/34.0) (2.0 /+0.5,1.5/1.0) 94.4 29.9 19.8 A1401B R-22/152a/124 (61.0/11.0/28.0) (2/+0.5,1.5/1.0) 92.8 32.3 23.4 A1401C R-22/152a/124 (33.0/15.0/52.0) (2/+0.5,1.5/1.0) 101 22.9 10.8 A1402A R-125/290/22 (60.0/2.0/38.0) (2.0/+0.1,1.0/2.0) 101.6 56.6 52.6 A1
35、402B R-125/290/22 (38.0/2.0/60.0) (2/+0.1,1/2) 94.7 53.0 48.8 A1403A R-290/22/218 (5.0/75.0/20.0) (+0.2,2/2/2) 92 47.2 44.1 A1403B R-290/22/218 (5.0/56.0/39.0) (+0.2,2/2/2) 103.3 46.8 44.1 A1404A R-125/143a/134a (44.0/52.0/4.0) (2/1/2) 97.6 51.9 50.4 A1405A R-22/152a/142b/C318 (45.0/7.0/5.5/42.5) (2
36、/1/1 /2) sum of R-152a and R-142b = (+0.0, 2.0)111.9 27.2 12.1406A R-22/600a/142b (55.0/4.0/41.0) (2/1/1) 89.9 26.9 10.3 A2407A R-32/125/134a (20.0/40.0/40.0) (2/2/2) 90.1 49.4 37.7 A1407B R-32/125/134a (10.0/70.0/20.0) (2/2/2) 102.9 52.2 44.3 A1407C R-32/125/134a (23.0/25.0/52.0) (2/2/2) 86.2 46.8
37、34.1 A1407D R-32/125/134a (15.0/15.0/70.0) (2/2/2) 91 38.9 26.9 A1407E R-32/125/134a (25.0/15.0/60.0) (2,2,2) 83.8 45.0 32.1 A1407F R-32/125/134a (30.0/30.0/40.0) (2,2,2) 82.1 51.0 39.5 A1408A R-125/143a/22 (7.0/46.0/47.0) (2/1/2) 87 49.9 49.0 A1409A R-22/124/142b (60.0/25.0/15.0) (2/2/1) 97.4 31.7
38、17.5 A1409B R-22/124/142b (65.0/25.0/10.0) (2/2/1) 96.7 33.7 21.5 A1410A R-32/125 (50.0/50.0) (+0.5,1.5/+1.5,0.5) 72.6 60.9 60.7 A1410B R-32/125 (45.0/55.0) (1/1) 75.6 60.7 60.5 A1411A R-1270/22/152a (1.5/87.5/11.0) (+0,1/+2,0/+0,1) 82.4 39.5 35.0 A2411B R-1270/22/152a (3.0/94.0/3.0) (+0,1/+2,0/+0,1
39、) 83.1 42.9 42.3 A2412A R-22/218/142b (70.0/5.0/25.0) (2/2/1) 92.2 33.5 19.8 A2413A R-218/134a/600a (9.0/88.0/3.0) (1/2/0,1) 104 20.7 17.7 A2414A R-22/124/600a/142b (51.0/28.5/4.0/16.5) (2/2/0.5/+0.5,1) 96.9 29.2 14.4 A1414B R-22/124/600a/142b (50.0/39.0/1.5/9.5) (2/2/0.5/+0.5,1) 101.6 29.9 15.0 A14
40、15A R-22/152a (82.0/18.0) (1/1) 81.9 35.5 30.5 A2415B R-22/152a (25.0/75.0) (1/1) 70.2 17.8 15.2 A2416A R-134a/124/600 (59.0/39.5/1.5) (+0.5,1/+1,0.5/+1,0.2) 111.9 10.1 7.2 A1417A R-125/134a/600 (46.6/50.0/3.4) (1.1/1/+0.1,0.4) 106.7 36.4 27.2 A1417B R-125/134a/600 (79.0/18.3/2.7) (1/1/+0.1,0.5) 113
41、.1 48.8 42.7 A1Table 1 Refrigerant Data and Safety Classifications (Continued)Refrigerant Number Chemical Namea,bChemical FormulaaMolecularMassaNormal Boiling Point,aFSafetyGroup29.4 2013 ASHRAE HandbookFundamentalsHCFCs, and HFCs) and sulfur hexafluoride, to be a smaller contrib-utor to global clim
42、ate change. On whether observed warming isattributable to human influence, IPCC (2007b) concludes that“Most of the observed increase in global averaged temperaturessince the mid-twentieth century about 1.2F is very likely 90%confident due to the observed increase in anthropogenic green-house gas con
43、centrations.”Global Environmental Characteristics of Refrigerants. At-mospheric release of CFC and HCFC refrigerants (see Table 3) con-tributes to depletion of the ozone layer. The measure of a materialsability to deplete stratospheric ozone is its ozone depletion poten-tial (ODP), a value relative
44、to that of R-11, which is 1.0. It is thenonzero ODP of these refrigerants that led to their phaseout underthe Montreal Protocol.418A R-290/22/152a (1.5/96.0/2.5) (0.5/1/0.5) 84.6 42.2 40.2 A2419A R-125/134a/E170 (77.0/19.0/4.0) (1/1/1) 109.3 44.7 32.8 A2420A R-134a/142b (88.0/12.0) (1,0/+0,1) 101.8
45、13.0 11.6 A1421A R-125/134a (58.0/42.0) (1/1) 111.8 41.5 31.9 A1421B R-125/134a (85.0/15.0) (1/1) 116.9 50.2 44.6 A1422A R-125/134a/600a (85.1/11.5/3.4) (1/1/+0.1,0.4) 113.6 51.7 47.4 A1422B R-125/134a/600a (55.0/42.0/3.0) (1/1/+0.1,0.5) 108.5 40.9 32.2 A1422C R-125/134a/600a (82.0/15.0/3.0) (1/1/+0
46、.1,0.5) 116.3 49.5 44.2 A1422D R-125/134a/600a (65.1/31.5/3.4) (+0.9,1.1/1/+0.1,0.4) 109.9 45.8 37.1 A1423A R-134a/227ea (52.5/47.5) (1/1) 126 11.6 10.3 A1424A R-125/134a/600a/600/601a (50.5/47.0/0.9/1.0/0.6) (1/1/+0.1,0.2/+0.1,0.2/+0.1,0.2) 108.4 38.4 27.9 A1425A R-32/134a/227ea (18.5/69.5/12.0) (0
47、.5/0.5/0.5) 90.3 36.6 24.3 A1426A R-125/134a/600a/601a (5.1/93.0/1.3/0.6) (1/1/+0.1,0.2/+0.1,0.2) 101.6 19.3 16.1 A1427A R-32/125/143a/134a (15.0/25.0/10.0/50.0) (2/2/2/2) 90.4 45.4 33.3 A1428A R-125/143a/290/600a (77.5/20.0/0.6/1.9) (1/1/+0.1,0.2/+0.1,0.2) 107.5 54.9 53.5 A1429A R-E170/152a/600a (6
48、0.0/10.0/30.0) (1/1/1) 50.8 14.8 14.1 A3430A R-152a/600a (76.0/24.0) (1/1) 64 17.7 17.3 A3431A R-290/152a (71.0/29.0) (1/1) 48.8 45.6 45.6 A3432A R-1270/E170 (80.0/20.0) (1/1) 42.8 51.9 50.1 A3433A R-1270/290 (30.0/70.0) (1/1) 43.5 48.3 47.6 A3433B R-1270/290 (5.0/95.0) (1/1) 44 44.9 44.5 A3433C R-1270/290 (25.0/75.0) (1/1) 43.6 47.7 47.0 A3434A R-125/143a/134a/600a (63.2/18.0/16.0/2.8) (1/1/1/+0.1,0.2) 105.7 49.0 44.1 A1435A R-E170/152a (80.0/20.0) (1/1) 49.04 15.0 14.6 A3436A R-290/600a (56.0/44.0) (1/1) 49.33 29.7 16.2 A3436B R-290/600a (52.0/48.0) (
