ASHRAE FUNDAMENTALS SI CH 31-2013 Physical Properties of Secondary Coolants (Brines).pdf

1、31.1CHAPTER 31PHYSICAL PROPERTIES OF SECONDARY COOLANTS (BRINES)Brines . 31.1Inhibited Glycols 31.4Halocarbons . 31.12Nonhalocarbon, Nonaqueous Fluids . 31.13N many refrigeration applications, heat is transferred to a second-Iary coolant, which can be any liquid cooled by the refrigerant andused to

2、transfer heat without changing state. These liquids are alsoknown as heat transfer fluids, brines, or secondary refrigerants.Other ASHRAE Handbook volumes describe various applica-tions for secondary coolants. In the 2010 ASHRAE HandbookRefrigeration, refrigeration systems are discussed in Chapter 1

3、3,their uses in food processing in Chapters 23 and 28 to 42, and icerinks in Chapter 44. In the 2011 ASHRAE HandbookHVAC Appli-cations, solar energy use is discussed in Chapter 35, and snow melt-ing and freeze protection in Chapter 51. Thermal storage is coveredin Chapter 51 of the 2012 ASHRAE Handb

4、ookHVAC Systems andEquipment.This chapter describes physical properties of several secondarycoolants and provides information on their use. Additional, lesswidely used secondary coolants such as ethyl alcohol or potassiumformate are not included in this chapter, but their physical propertiesare summ

5、arized in Melinder (2007). Physical property data fornitrate and nitrite salt solutions used for stratified thermal energystorage are presented by Andrepont (2012). The chapter alsoincludes information on corrosion protection. Supplemental infor-mation on corrosion inhibition can be found in Chapter

6、 49 of the2011 ASHRAE HandbookHVAC Applications and Chapter 13 ofthe 2010 ASHRAE HandbookRefrigeration.BRINESPhysical PropertiesWater solutions of calcium chloride and sodium chloride havehistorically been the most common refrigeration brines. Tables 1 and2 list the properties of pure calcium chlori

7、de brine and sodium chlo-ride brine. For commercial grades, use the formulas in the footnotesto these tables. For calcium chloride brines, Figure 1 shows specificheat, Figure 2 shows the ratio of mass of solution to that of water,Figure 3 shows viscosity, and Figure 4 shows thermal conductivity.Figu

8、res 5 to 8 show the same properties for sodium chloride brines._The preparation of this chapter is assigned to TC 3.1, Refrigerants and Secondary Coolants.Table 1 Properties of Pure Calcium Chloride* BrinesPure CaCl2, % by MassSpecific Heat at 15C, J/(kgK)Crystallization Starts, CDensity at 16C, kg/

9、m3Density at Various Temperatures, kg/m3CaCl2Brine 20C 10C 0C 10C0 4184 0.0 0.0 9995 3866 2.4 52.2 1044 1042 10416 3824 2.9 63.0 1049 1051 10507 3757 3.4 74.2 1059 1060 10598 3699 4.1 85.5 1068 1070 10689 3636 4.7 96.9 1078 1079 107710 3577 5.4 108.6 1087 1088 108611 3523 6.2 120.5 1095 1097 109512

10、3464 7.1 132.5 1104 1107 110413 3414 8.0 144.8 1113 1116 111414 3364 9.2 157.1 1123 1126 112315 3318 10.3 169.8 1132 1140 1136 113316 3259 11.6 182.6 1141 1150 1145 114217 3209 13.0 195.7 1152 1160 1155 115218 3163 14.5 209.0 1161 1170 1165 116219 3121 16.2 222.7 1171 1179 1175 117220 3084 18.0 236.

11、0 1180 1189 1185 118221 3050 19.9 249.6 118922 2996 22.1 264.3 1201 1214 1210 1206 120223 2958 24.4 278.7 121124 2916 26.8 293.5 1223 1235 1231 1227 122325 2882 29.4 308.2 123226 2853 32.1 323.1 124227 2816 35.1 338.5 125328 2782 38.8 354.0 126429 2753 45.2 369.9 127529.87 2741 55.0 378.8 128930 273

12、2 46.0 358.4 129432 2678 28.6 418.1 131634 2636 15.4 452.0 1339Source: CCI (1953)*Mass of Type 1 (77% min.) CaCl2= (mass of pure CaCl2)/(0.77). Mass of Type 2 (94% min.) CaCl2= (mass of pure CaCl2)/(0.94).31.2 2013 ASHRAE HandbookFundamentals (SI)Fig. 1 Specific Heat of Calcium Chloride Brines(CCI 1

13、953)Fig. 2 Density of Calcium Chloride Brines(CCI 1953)Fig. 3 Viscosity of Calcium Chloride Brines(CCI 1953)Fig. 4 Thermal Conductivity of Calcium Chloride Brines(CCI 1953)Physical Properties of Secondary Coolants (Brines) 31.3Table 2 Properties of Pure Sodium ChlorideaBrinesPure NaCl,% by MassSpeci

14、fic Heat at 15C, J/(kgK)CrystallizationStarts, CDensity at 16C, kg/m3Density at Various Temperatures, kg/m3NaCl Brine 10C 0C 10C 20C0 4184 0.0 0.0 100053925 2.9 51.7 1035 1038.1 1036.5 1034.06387 3.6 62.5 1043 1045.8 1043.9 1041.27336 4.3 73.4 1049 1053.7 1051.4 1048.583795 5.0 84.6 1057 1061.2 1058

15、.9 1055.8933 5.8 95.9 1065 1069.0 1066.4 1063.210 3715 6.6 107.2 1072 1076.8 1074.0 1070.611 3678 7.3 118.8 1080 1084.8 1081.6 1078.112 3640 8.2 130.3 1086 1092.4 1089.6 1085.613 3607 9.1 142.2 1094 1100.3 1097.0 1093.214 3573 10.1 154.3 1102 1108.2 1104.7 1100.815 3544 10.9 166.5 1110 1119.4 1116.2

16、 1112.5 1108.516 3515 11.9 178.9 1118 1127.6 1124.2 1120.4 1116.217 3485 13.0 191.4 1126 1135.8 1132.2 1128.3 1124.018 3456 14.1 204.1 1134 1144.1 1140.3 1136.2 1131.819 3427 15.3 217.0 1142 1153.4 1148.5 1144.3 1139.720 3402 16.5 230.0 1150 1160.7 1156.7 1154.1 1147.721 3376 17.8 243.2 1158 1169.1

17、1165.0 1160.5 1155.822 3356 19.1 256.6 1166 1177.6 1173.3 1168.7 1163.923 3330 20.6 270.0 1174 1186.1 1181.7 1177.0 1172.024 3310 15.7 283.7 1182 1194.7 1190.1 1185.3 1180.325 3289 8.8 297.5 119025.2 0.0aMass of commercial NaC1 required = (mass of pure NaCl required)/(% purity).Fig. 5 Specific Heat

18、of Sodium Chloride Brines(adapted from Carrier 1959)Fig. 6 Density of Sodium Chloride Brines(adapted from Carrier 1959)31.4 2013 ASHRAE HandbookFundamentals (SI)Brine applications in refrigeration are mainly in industrialmachinery and in skating rinks. Corrosion is the principal problemfor calcium c

19、hloride brines, especially in ice-making tanks wheregalvanized iron cans are immersed.Ordinary salt (sodium chloride) is used where contact with calci-um chloride is intolerable (e.g., the brine fog method of freezing fishand other foods). It is used as a spray to air-cool unit coolers to preventfro

20、st formation on coils. In most refrigerating work, the lower freez-ing point of calcium chloride solution makes it more convenient to use.Commercial calcium chloride, available as Type 1 (77% mini-mum) and Type 2 (94% minimum), is marketed in flake, solid, andsolution forms; flake form is used most

21、extensively. Commercialsodium chloride is available both in crude (rock salt) and refinedgrades. Because magnesium salts tend to form sludge, their pres-ence in sodium or calcium chloride is undesirable.Corrosion InhibitionAll brine systems must be treated to control corrosion and depos-its. Histori

22、cally, chloride-based brines were maintained at neutralpH and treated with sodium chromate. However, using chromate asa corrosion inhibitor is no longer deemed acceptable because of itsdetrimental environmental effects. Chromate has been placed onhazardous substance lists by several regulatory agenc

23、ies. For exam-ple, the U.S. Agency for Toxic Substances and Disease Registrys(ATSDR 2011) Priority List of Hazardous Substances ranks hexa-valent chromium 17th out of 275 chemicals of concern (based onfrequency, toxicity, and potential for human exposure at NationalPriorities List facilities). Conse

24、quently, hexavalent chrome and sev-eral chromates are also listed on several state right-to-know hazard-ous substance lists, including New Jersey, California, Minnesota,Pennsylvania and others.Instead of chromate, most brines use a sodium-nitrite-based in-hibitor ranging from approximately 3000 mg/k

25、g in calcium brines to4000 mg/kg in sodium brines. Other, proprietary organic inhibitorsare also available to mitigate the inherent corrosiveness of brines.Before using any inhibitor package, review federal, state, andlocal regulations concerning the use and disposal of the spent fluids.If the regul

26、ations prove too restrictive, an alternative inhibition sys-tem should be considered.INHIBITED GLYCOLSEthylene glycol and propylene glycol, when properly inhibitedfor corrosion control, are used as aqueous-freezing-point depres-sants (antifreeze) and heat transfer media. Their chief attributes areth

27、eir ability to efficiently lower the freezing point of water, their lowvolatility, and their relatively low corrosivity when properly inhib-ited. Inhibited ethylene glycol solutions have better thermophysicalproperties than propylene glycol solutions, especially at lower tem-peratures. However, the

28、less toxic propylene glycol is preferred forapplications involving possible human contact or where mandatedby regulations.Physical PropertiesEthylene glycol and propylene glycol are colorless, practicallyodorless liquids that are miscible with water and many organic com-pounds. Table 3 shows propert

29、ies of the pure materials.The freezing and boiling points of aqueous solutions of ethyleneglycol and propylene glycol are given in Tables 4 and 5. Note thatincreasing the concentration of ethylene glycol above 60% by massFig. 7 Viscosity of Sodium Chloride Brines(adapted from Carrier 1959)Fig. 8 The

30、rmal Conductivity of Sodium Chloride Brines(adapted from Carrier 1959)Table 3 Physical Properties of Ethylene Glycol and Propylene GlycolPropertyEthylene GlycolPropylene GlycolRelative molecular mass 62.07 76.10Density at 20C, kg/m31113 1036Boiling point, Cat 101.3 kPa 198 187at 6.67 kPa 123 116at 1

31、.33 kPa 89 85Vapor pressure at 20C, Pa 6.7 9.3Freezing point, C 12.7 Sets to glass below 51CViscosity, mPasat 0C 57.4 243at 20C 20.9 60.5at 40C 9.5 18.0Refractive index nDat 20C 1.4319 1.4329Specific heat at 20C, kJ/(kgK) 2.347 2.481Heat of fusion at 12.7C, kJ/kg 187 Heat of vaporization at 101.3 kP

32、a, kJ/kg 846 688Heat of combustion at 20C, MJ/kg 19.246 23.969Sources: Dow Chemical (2001a, 2001b)Physical Properties of Secondary Coolants (Brines) 31.5causes the freezing point of the solution to increase. Propyleneglycol solutions above 60% by mass do not have freezing points.Instead of freezing,

33、 propylene glycol solutions supercool and be-come a glass (a liquid with extremely high viscosity and the appear-ance and properties of a noncrystalline amorphous solid). On thedilute side of the eutectic (the mixture at which freezing produces asolid phase of the same composition), ice forms on fre

34、ezing; on theconcentrated side, solid glycol separates from solution on freezing.The freezing rate of such solutions is often quite slow, but, in time,they set to a hard, solid mass.Physical properties (i.e., density, specific heat, thermal con-ductivity, and viscosity) for aqueous solutions of ethy

35、lene glycolcan be found in Tables 6 to 9 and Figures 9 to 12; similar data foraqueous solutions of propylene glycol are in Tables 10 to 13 andFigures 13 to 16. Densities are for aqueous solutions of industriallyinhibited glycols, and are somewhat higher than those for pureglycol and water alone. Typ

36、ical corrosion inhibitor packages do notsignificantly affect other physical properties. Physical properties forFig. 9 Density of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %)(Dow Chemical 2001b)Fig. 10 Specific Heat of Aqueous Solutions of Industrially Inhibited Ethylene Glyco

37、l (vol. %)(Dow Chemical 2001b)Fig. 11 Thermal Conductivity of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %)(Dow Chemical 2001b)Fig. 12 Viscosity of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %)(Dow Chemical 2001b)Fig. 13 Density of Aqueous Solutions of I

38、ndustrially Inhibited Propylene Glycol (vol. %)(Dow Chemical 2001b)31.6 2013 ASHRAE HandbookFundamentals (SI)Table 4 Freezing and Boiling Points of Aqueous Solutions of Ethylene GlycolPercent Ethylene GlycolFreezing Point, CBoiling Point, C at 100.7 kPaBy Mass By Volume0.0 0.0 0.0 100.05.0 4.4 1.4 1

39、00.610.0 8.9 3.2 101.115.0 13.6 5.4 101.720.0 18.1 7.8 102.221.0 19.2 8.4 102.222.0 20.1 8.9 102.223.0 21.0 9.5 102.824.0 22.0 10.2 102.825.0 22.9 10.7 103.326.0 23.9 11.4 103.327.0 24.8 12.0 103.328.0 25.8 12.7 103.929.0 26.7 13.3 103.930.0 27.7 14.1 104.431.0 28.7 14.8 104.432.0 29.6 15.4 104.433.

40、0 30.6 16.2 104.434.0 31.6 17.0 104.435.0 32.6 17.9 105.036.0 33.5 18.6 105.037.0 34.5 19.4 105.038.0 35.5 20.3 105.039.0 36.5 21.3 105.040.0 37.5 22.3 105.641.0 38.5 23.2 105.642.0 39.5 24.3 105.643.0 40.5 25.3 106.144.0 41.5 26.4 106.145.0 42.5 27.5 106.746.0 43.5 28.8 106.747.0 44.5 29.8 106.748.

41、0 45.5 31.1 106.749.0 46.6 32.6 106.750.0 47.6 33.8 107.251.0 48.6 35.1 107.252.0 49.6 36.4 107.253.0 50.6 37.9 107.854.0 51.6 39.3 107.855.0 52.7 41.1 108.356.0 53.7 42.6 108.357.0 54.7 44.2 108.958.0 55.7 45.6 108.959.0 56.8 47.1 109.460.0 57.8 48.3 110.065.0 62.8 * 112.870.0 68.3 * 116.775.0 73.6

42、 * 120.080.0 78.9 46.8 123.985.0 84.3 36.9 133.990.0 89.7 29.8 140.695.0 95.0 19.4 158.3Source: Dow Chemical (2001b)*Freezing points are below 50C.Table 5 Freezing and Boiling Points of Aqueous Solutions of Propylene GlycolPercent Propylene GlycolFreezing Point,CBoiling Point, C at 100.7 kPaBy Mass

43、By Volume0.0 0.0 0.0 100.05.0 4.8 1.6 100.010.0 9.6 3.3 100.015.0 14.5 5.1 100.020.0 19.4 7.1 100.621.0 20.4 7.6 100.622.0 21.4 8.0 100.623.0 22.4 8.6 100.624.0 23.4 9.1 100.625.0 24.4 9.6 101.126.0 25.3 10.2 101.127.0 26.4 10.8 101.128.0 27.4 11.4 101.729.0 28.4 12.0 101.730.0 29.4 12.7 102.231.0 3

44、0.4 13.4 102.232.0 31.4 14.1 102.233.0 32.4 14.8 102.234.0 33.5 15.6 102.235.0 34.4 16.4 102.836.0 35.5 17.3 102.837.0 36.5 18.2 102.838.0 37.5 19.1 103.339.0 38.5 20.1 103.340.0 39.6 21.1 103.941.0 40.6 22.1 103.942.0 41.6 23.2 103.943.0 42.6 24.3 103.944.0 43.7 25.5 103.945.0 44.7 26.7 104.446.0 4

45、5.7 27.9 104.447.0 46.8 29.3 104.448.0 47.8 30.6 105.049.0 48.9 32.1 105.050.0 49.9 33.5 105.651.0 50.9 35.0 105.652.0 51.9 36.6 105.653.0 53.0 38.2 106.154.0 54.0 39.8 106.155.0 55.0 41.6 106.156.0 56.0 43.3 106.157.0 57.0 45.2 106.758.0 58.0 47.1 106.759.0 59.0 49.0 106.760.0 60.0 51.1 107.265.0 6

46、5.0 * 108.370.0 70.0 * 110.075.0 75.0 * 113.980.0 80.0 * 118.385.0 85.0 * 125.090.0 90.0 * 132.295.0 95.0 * 154.4Source: Dow Chemical (2001a)*Above 60% by mass, solutions do not freeze but become a glass.Physical Properties of Secondary Coolants (Brines) 31.7Table 6 Density of Aqueous Solutions of E

47、thylene GlycolTemperature, CConcentrations in Volume Percent Ethylene Glycol10% 20% 30% 40% 50% 60% 70% 80% 90%35 1089.94 1104.60 1118.61 1132.1130 1089.04 1103.54 1117.38 1130.7225 1088.01 1102.36 1116.04 1129.21 1141.8720 1071.98 1086.87 1101.06 1114.58 1127.57 1140.0715 1070.87 1085.61 1099.64 11

48、12.99 1125.82 1138.1410 1054.31 1069.63 1084.22 1098.09 1111.28 1123.94 1136.095 1036.85 1053.11 1068.28 1082.71 1096.43 1109.45 1121.94 1133.910 1018.73 1035.67 1051.78 1066.80 1081.08 1094.64 1107.50 1119.82 1131.625 1017.57 1034.36 1050.33 1065.21 1079.33 1092.73 1105.43 1117.58 1129.2010 1016.28

49、 1032.94 1048.76 1063.49 1077.46 1090.70 1103.23 1115.22 1126.6715 1014.87 1031.39 1047.07 1061.65 1075.46 1088.54 1100.92 1112.73 1124.0120 1013.34 1029.72 1045.25 1059.68 1073.35 1086.27 1098.48 1110.13 1121.2325 1011.69 1027.93 1043.32 1057.60 1071.11 1083.87 1095.92 1107.40 1118.3230 1009.92 1026.02 1041.26 1055.39 1068.75 1081.35 1093.24 1104.55 1115.3035 1008.02 1023.99 1039.08 10