1、29.1CHAPTER 29REFRIGERANTSRefrigerant 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 fo
3、r 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 c
4、ompromises 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 refri
5、gerantof 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, l
7、atentheat 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 viscosit
8、y)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, and
9、 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 refrigerant
10、 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 tobe phased out of production under the Montreal Protocol (UNEP2009). In the United States, production and importation
14、of CFCswere banned completely in 1996. HCFCs are being phased down,with complete phaseout set for 2030. In 2010, to meet the MontrealProtocol phasedown schedule, U.S. regulations banned productionand importation of HCFC-142b and HCFC-22 for use in new equip-ment. Reclaimed CFC and HCFC refrigerants
15、that meet the require-ments of AHRI Standard 700 can continue to be used for servicingexisting systems. A complete list of U.S. regulations for CFC andHCFC refrigerants, including phaseout schedules, may be found athttp:/www.epa.gov/ozone/strathome.html. Phaseout schedules forCFCs and HCFCs for both
16、 developed and developing countries aresummarized on the Ozone 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 34 K warmer than would be the case if these gases and pa
18、rti-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 GHGof concern is CO2released to the atmosphere when fossi
19、l fuels (coal,oil, and natural gas) are burned for energy. Methane (CH4), nitrousoxide (N2O), CFCs, HCFCs, HFCs, hydrofluoroethers (HFEs), hy-drofluoroolefins (HFOs), perfluorocarbons (PFCs), nitrogen trifluor-ide (NF3), and sulfur hexafluoride (SF6) are also GHGs.In 1988, the United Nations Environ
20、ment Programme (UNEP) andthe World Meteorological Organization (WMO) established the Inter-governmental Panel on Climate Change (IPCC) to provide an objec-tive source of information about the causes of climate change, itspotential environmental and socioeconomic consequences, and theadaptation and m
21、itigation options to respond to it. According to IPCC(2007a), atmospheric concentration of carbon dioxide has increasedby more than 35% over the past 250 years, primarily from burning fos-sil fuels, with some contribution from deforestation. Concentration ofmethane has increased by over 145%, and ni
22、trous oxide by about 18%.IPCC (2007a) deems atmospheric concentrations of fluorochemicals,including fluorocarbon gases (CFCs, HCFCs, and HFCs) and sulfurThe preparation of this chapter is assigned to TC 3.1, Refrigerants andSecondary Coolants.29.2 2013 ASHRAE HandbookFundamentals (SI)Table 1 Refrige
23、rant Data and Safety ClassificationsRefrigerant Number Chemical Namea,bChemical FormulaaMolecularMassaNormal Boiling Point,aCSafetyGroupMethane Series11 Trichlorofluoromethane CCl3F 137.4 24 A112 Dichlorodifluoromethane CCl2F2120.9 30 A112B1 Bromochlorodifluoromethane CBrClF2165.4 413 Chlorotrifluor
24、omethane CClF3104.5 81 A113B1 Bromotrifluoromethane CBrF3148.9 58 A114 Tetrafluoromethane (carbon tetrafluoride) CF488.0 128 A121 Dichlorofluoromethane CHCl2F12.9 9B22 Chlorodifluoromethane CHClF286.5 41 A123 Trifluoromethane CHF370.0 82 A130 Dichloromethane (methylene chloride) CH2Cl284.9 40 B231 C
25、hlorofluoromethane CH2ClF 68.5 932 Difluoromethane (methylene fluoride) CH2F252.0 52 A2L40 Chloromethane (methyl chloride) CH3Cl 50.4 24 B241 Fluoromethane (methyl fluoride) CH3F34.7850 Methane CH416.0 161 A3Ethane Series113 1,1,2-trichloro-1,2,2-trifluoroethane CCl2FCClF2187.4 48 A1114 1,2-dichloro
26、-1,1,2,2-tetrafluoroethane CClF2CClF2170.9 4 A1115 Chloropentafluoroethane CClF2CF3154.5 39 A1116 Hexafluoroethane CF3CF3138.0 78 A1123 2,2-dichloro-1,1,1-trifluoroethane CHCl2CF3153.0 27 B1124 2-chloro-1,1,1,2-tetrafluoroethane CHClFCF3136.5 12 A1125 Pentafluoroethane CHF2CF3120.0 48 A1134a 1,1,1,2
27、-tetrafluoroethane CH2FCF3102.0 26 A1141b 1,1-dichloro-1-fluoroethane CH3CCl2F 117.0 32142b 1-chloro-1,1-difluoroethane CH3CClF2100.5 10 A2143a 1,1,1-trifluoroethane CH3CF384.0 47 A2L152a 1,1-difluoroethane CH3CHF266.0 24 A2170 Ethane CH3CH330.0 89 A3EthersE170 Dimethyl ether CH3OCH346.0 25 A3Propan
28、e Series218 Octafluoropropane CF3CF2CF3188.0 37 A1227ea 1,1,1,2,3,3,3-heptafluoropropane CF3CHFCF3170.0 16 A1236fa 1,1,1,3,3,3-hexafluoropropane CF3CH2CF3152.0 1 A1245fa 1,1,1,3,3-pentafluoropropane CF3CH2CHF2134.0 15 B1290 Propane CH3CH2CH344.0 42 A3Cyclic Organic Compounds (see Table 2 for blends)
29、C318 Octafluorocyclobutane (CF2)4 200.0 6 A1Miscellaneous Organic CompoundsHydrocarbons600 Butane CH3CH2CH2CH358.1 0 A3600a 2-methylpropane (isobutane) CH(CH3)2CH358.1 12 A3601 Pentane CH3(CH2)3CH372.15 36.1 A3601a 2-methylbutane (isopentane) (CH3)2CHCH2CH372.15 27.8 A3Oxygen Compounds610 Ethyl ethe
30、r CH3CH2OCH2CH374.1 35611 Methyl formate HCOOCH360.0 32 B2Sulfur Compounds620 (Reserved for future assignment)Nitrogen Compounds630 Methanamine (methyl amine) CH3NH231.1 7631 Ethanamine (ethyl amine) CH3CH2(NH2)45.1 17Refrigerants 29.3Inorganic Compounds702 Hydrogen H22.0 253 A3704 Helium He 4.0 269
31、 A1717 Ammonia NH317.0 33 B2L718 Water H2O18.10A1720 Neon Ne 20.2 246 A1728 Nitrogen N228.1 196 A1732 Oxygen O232.0 183740 Argon Ar 39.9 186 A1744 Carbon dioxide CO244.0 78cA1744A Nitrous oxide N2O44.090764 Sulfur dioxide SO264.1 10 B1Unsaturated Organic Compounds1150 Ethene (ethylene) CH2=CH228.1 1
32、04 A31234yf 2,3,3,3-tetrafluoro-1-propene CF3CF=CH2114.0 29.4 A2L1234ze(E) Trans-1,3,3,3-tetrafluoro-1-propene CF3CH=CHF 114.0 19.0 A2L1270 Propene (propylene) CH3CH=CH242.1 48 A3Source: ANSI/ASHRAE Standard 34-2010.aChemical name, chemical formula, molecular mass, and normal boiling point are notpa
33、rt of this standard.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, CNormal Dew Point, CSafety GroupZeotrop
34、es400 R-12/114 (must be specified) A1401A R-22/152a/124 (53.0/13.0/34.0) (2.0 /+0.5,1.5/1.0) 94.4 34.4 28.8 A1401B R-22/152a/124 (61.0/11.0/28.0) (2/+0.5,1.5/1.0) 92.8 35.7 30.8 A1401C R-22/152a/124 (33.0/15.0/52.0) (2/+0.5,1.5/1.0) 101 30.5 23.8 A1402A R-125/290/22 (60.0/2.0/38.0) (2.0/+0.1,1.0/2.0
35、) 101.6 49.2 47.0 A1402B R-125/290/22 (38.0/2.0/60.0) (2/+0.1,1/2) 94.7 47.2 44.9 A1403A R-290/22/218 (5.0/75.0/20.0) (+0.2,2/2/2) 92 44.0 42.3 A1403B R-290/22/218 (5.0/56.0/39.0) (+0.2,2/2/2) 103.3 43.8 42.3 A1404A R-125/143a/134a (44.0/52.0/4.0) (2/1/2) 97.6 46.6 45.8 A1405A R-22/152a/142b/C318 (4
36、5.0/7.0/5.5/42.5) (2/1/1 /2) sum of R-152a and R-142b = (+0.0, 2.0)111.9 32.9 24.5406A R-22/600a/142b (55.0/4.0/41.0) (2/1/1) 89.9 32.7 23.5 A2407A R-32/125/134a (20.0/40.0/40.0) (2/2/2) 90.1 45.2 38.7 A1407B R-32/125/134a (10.0/70.0/20.0) (2/2/2) 102.9 46.8 42.4 A1407C R-32/125/134a (23.0/25.0/52.0
37、) (2/2/2) 86.2 43.8 36.7 A1407D R-32/125/134a (15.0/15.0/70.0) (2/2/2) 91 39.4 32.7 A1407E R-32/125/134a (25.0/15.0/60.0) (2,2,2) 83.8 42.8 35.6 A1407F R-32/125/134a (30.0/30.0/40.0) (2,2,2) 82.1 46.1 39.7 A1408A R-125/143a/22 (7.0/46.0/47.0) (2/1/2) 87 45.5 45.0 A1409A R-22/124/142b (60.0/25.0/15.0
38、) (2/2/1) 97.4 35.4 27.5 A1409B R-22/124/142b (65.0/25.0/10.0) (2/2/1) 96.7 36.5 29.7 A1410A R-32/125 (50.0/50.0) (+0.5,1.5/+1.5,0.5) 72.6 51.6 51.5 A1410B R-32/125 (45.0/55.0) (1/1) 75.6 51.5 51.4 A1411A R-1270/22/152a (1.5/87.5/11.0) (+0,1/+2,0/+0,1) 82.4 39.7 37.2 A2411B R-1270/22/152a (3.0/94.0/
39、3.0) (+0,1/+2,0/+0,1) 83.1 41.6 41.3 A2412A R-22/218/142b (70.0/5.0/25.0) (2/2/1) 92.2 36.4 28.8 A2413A R-218/134a/600a (9.0/88.0/3.0) (1/2/0,1) 104 29.3 27.6 A2414A R-22/124/600a/142b (51.0/28.5/4.0/16.5) (2/2/0.5/+0.5,1) 96.9 34.0 25.8 A1414B R-22/124/600a/142b (50.0/39.0/1.5/9.5) (2/2/0.5/+0.5,1)
40、 101.6 34.4 26.1 A1415A R-22/152a (82.0/18.0) (1/1) 81.9 37.5 34.7 A2415B R-22/152a (25.0/75.0) (1/1) 70.2 27.7 26.2 A2416A R-134a/124/600 (59.0/39.5/1.5) (+0.5,1/+1,0.5/+1,0.2) 111.9 23.4 21.8 A1417A R-125/134a/600 (46.6/50.0/3.4) (1.1/1/+0.1,0.4) 106.7 38.0 32.9 A1417B R-125/134a/600 (79.0/18.3/2.
41、7) (1/1/+0.1,0.5) 113.1 44.9 41.5 A1Table 1 Refrigerant Data and Safety Classifications (Continued)Refrigerant Number Chemical Namea,bChemical FormulaaMolecularMassaNormal Boiling Point,aCSafetyGroup29.4 2013 ASHRAE HandbookFundamentals (SI)hexafluoride, to be a smaller contributor to global climate
42、 change. Onwhether observed warming is attributable to human influence, IPCC(2007b) concludes that “Most of the observed increase in global aver-aged temperatures since the mid-twentieth century about 0.65 K isvery likely 90% confident due to the observed increase in anthropo-genic greenhouse gas co
43、ncentrations.”Global Environmental Characteristics of Refrigerants. Atmo-spheric release of CFC and HCFC refrigerants (see Table 3) contributesto depletion of the ozone layer. The measure of a materials ability todeplete stratospheric ozone is its ozone depletion potential (ODP), avalue relative to
44、that of R-11, which is 1.0. It is the nonzero ODP ofthese refrigerants that led to their phaseout under the Montreal Protocol.418A R-290/22/152a (1.5/96.0/2.5) (0.5/1/0.5) 84.6 41.2 40.1 A2419A R-125/134a/E170 (77.0/19.0/4.0) (1/1/1) 109.3 42.6 36.0 A2420A R-134a/142b (88.0/12.0) (1,0/+0,1) 101.8 25
45、.0 24.2 A1421A R-125/134a (58.0/42.0) (1/1) 111.8 40.8 35.5 A1421B R-125/134a (85.0/15.0) (1/1) 116.9 45.7 42.6 A1422A R-125/134a/600a (85.1/11.5/3.4) (1/1/+0.1,0.4) 113.6 46.5 44.1 A1422B R-125/134a/600a (55.0/42.0/3.0) (1/1/+0.1,0.5) 108.5 40.5 35.6 A1422C R-125/134a/600a (82.0/15.0/3.0) (1/1/+0.1
46、,0.5) 116.3 45.3 42.3 A1422D R-125/134a/600a (65.1/31.5/3.4) (+0.9,1.1/1/+0.1,0.4) 109.9 43.2 38.4 A1423A R-134a/227ea (52.5/47.5) (1/1) 126 24.2 23.5 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 39.1 33.3 A1425A R-32/134a/227ea (18.5/69.5/12.0) (0.5
47、/0.5/0.5) 90.3 38.1 31.3 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 28.5 26.7 A1427A R-32/125/143a/134a (15.0/25.0/10.0/50.0) (2/2/2/2) 90.4 43.0 36.3 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 48.3 47.5 A1429A R-E170/152a/600a (60.
48、0/10.0/30.0) (1/1/1) 50.8 26.0 25.6 A3430A R-152a/600a (76.0/24.0) (1/1) 64 27.6 27.4 A3431A R-290/152a (71.0/29.0) (1/1) 48.8 43.1 43.1 A3432A R-1270/E170 (80.0/20.0) (1/1) 42.8 46.6 45.6 A3433A R-1270/290 (30.0/70.0) (1/1) 43.5 44.6 44.2 A3433B R-1270/290 (5.0/95.0) (1/1) 44 42.7 42.5 A3433C R-1270/290 (25.0/75.0) (1/1) 43.6 44.3 43.9 A3434A R-125/143a/134a/600a (63.2/18.0/16.0/2.8) (1/1/1/+0.1,0.2) 105.7 45.0 42.3 A1435A R-E170/152a (80.0/20.0) (1/1) 49.04 26.1 25.9 A3436A R-290/600a (56.0/44.0) (1/1) 49.33 34.3 26.2 A3436B R-290/600a (52.0/4
