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

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1、31.1CHAPTER 31 PHYSICAL PROPERTIES OF SECONDARY COOLANTS (BRINES)Brines . 31.1Inhibited Glycols 31.4Halocarbons . 31.13Nonhalocarbon, 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 t

2、ransfer 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 13

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 Handbo

4、okHVAC 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 summa

5、rized 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 chlorid

7、e 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.Figur

8、es 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 ChlorideaBrinesPure CaCl2,% by MassRatio of Mass to Water at 60FRelative Density, Degrees BaumcSpecific Heat at

9、 60F,Btu/lbFCrystalli-zation Starts, FMass per Unit Volumebat 60F Ratio of Mass at Various Temperatures to Water at 60FCaCl2,lb/galBrine,lb/galCaCl2,lb/ft3Brine,lb/ft34F 14F 32F 50F0 1.000 0.0 1.000 32.0 0.000 8.34 0.00 62.405 1.044 6.1 0.924 27.7 0.436 8.717 3.26 65.15 1.043 1.0426 1.050 7.0 0.914

10、26.8 0.526 8.760 3.93 65.52 1.052 1.0517 1.060 8.2 0.898 25.9 0.620 8.851 4.63 66.14 1.061 1.0608 1.069 9.3 0.884 24.6 0.714 8.926 5.34 66.70 1.071 1.0699 1.078 10.4 0.869 23.5 0.810 9.001 6.05 67.27 1.080 1.07810 1.087 11.6 0.855 22.3 0.908 9.076 6.78 67.83 1.089 1.08711 1.096 12.6 0.842 20.8 1.006

11、 9.143 7.52 68.33 1.098 1.09612 1.105 13.8 0.828 19.3 1.107 9.227 8.27 68.95 1.108 1.10513 1.114 14.8 0.816 17.6 1.209 9.302 9.04 69.51 1.117 1.11514 1.124 15.9 0.804 15.5 1.313 9.377 9.81 70.08 1.127 1.12415 1.133 16.9 0.793 13.5 1.418 9.452 10.60 70.64 1.139 1.137 1.13416 1.143 18.0 0.779 11.2 1.5

12、26 9.536 11.40 71.26 1.149 1.146 1.14317 1.152 19.1 0.767 8.6 1.635 9.619 12.22 71.89 1.159 1.156 1.15318 1.162 20.2 0.756 5.9 1.747 9.703 13.05 72.51 1.169 1.166 1.16319 1.172 21.3 0.746 2.8 1.859 9.786 13.90 73.13 1.180 1.176 1.17320 1.182 22.1 0.737 0.4 1.970 9.853 14.73 73.63 1.190 1.186 1.18321

13、 1.192 23.0 0.729 3.9 2.085 9.928 15.58 74.1922 1.202 24.4 0.716 7.8 2.208 10.037 16.50 75.00 1.215 1.211 1.207 1.20323 1.212 25.5 0.707 11.9 2.328 10.120 17.40 75.6324 1.223 26.4 0.697 16.2 2.451 10.212 18.32 76.32 1.236 1.232 1.228 1.22425 1.233 27.4 0.689 21.0 2.574 10.295 19.24 76.9426 1.244 28.

14、3 0.682 25.8 2.699 10.379 20.17 77.5627 1.254 29.3 0.673 31.2 2.827 10.471 21.13 78.2528 1.265 30.4 0.665 37.8 2.958 10.563 22.10 78.9429 1.276 31.4 0.658 49.4 3.090 10.655 23.09 79.6229.87 1.290 32.6 0.655 67.0 3.16 10.75 23.65 80.4530 1.295 33.0 0.653 50.8 3.22 10.80 24.06 80.7632 1.317 34.9 0.640

15、 19.5 3.49 10.98 26.10 82.1434 1.340 36.8 0.630 4.3 3.77 11.17 28.22 83.57Source: CCI (1953)aMass 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).bMass of water per unit volume = Brine mass minus CaCl2mass.cAt 60F.31.2 2013 ASHRAE

16、HandbookFundamentalsFig. 1 Specific Heat of Calcium Chloride Brines(CCI 1953)Fig. 2 Specific Gravity 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 (Bri

17、nes) 31.3Table 2 Properties of Pure Sodium ChlorideaBrinesPure NaCl,% by MassRatio of Mass to Water at 59FRelative Density, Degrees BaumbSpecific Heat at 59F,Btu/lbFCrystalli-zation Starts, FMass per Unit Volume at 60F Ratio of Mass at Various Temperatures to Water at 60FNaCl,lb/galBrine,lb/galNaCl,

18、lb/ft3Brine,lb/ft314F32F50F68F0 1.000 0.0 1.000 32.0 0.000 8.34 0.000 62.45 1.035 5.1 0.938 26.7 0.432 8.65 3.230 64.6 1.0382 1.0366 1.03416 1.043 6.1 0.927 25.5 0.523 8.71 3.906 65.1 1.0459 1.0440 1.04137 1.050 7.0 0.917 24.3 0.613 8.76 4.585 65.5 1.0536 1.0515 1.04868 1.057 8.0 0.907 23.0 0.706 8.

19、82 5.280 66.0 1.0613 1.0590 1.05599 1.065 9.0 0.897 21.6 0.800 8.89 5.985 66.5 1.0691 1.0665 1.063310 1.072 10.1 0.888 20.2 0.895 8.95 6.690 66.9 1.0769 1.0741 1.070711 1.080 10.8 0.879 18.8 0.992 9.02 7.414 67.4 1.0849 1.0817 1.078212 1.087 11.8 0.870 17.3 1.090 9.08 8.136 67.8 1.0925 1.0897 1.0857

20、13 1.095 12.7 0.862 15.7 1.188 9.14 8.879 68.3 1.1004 1.0933 1.097114 1.103 13.6 0.854 14.0 1.291 9.22 9.632 68.8 1.1083 1.1048 1.100915 1.111 14.5 0.847 12.3 1.392 9.28 10.395 69.3 1.1195 1.1163 1.1126 1.108616 1.118 15.4 0.840 10.5 1.493 9.33 11.168 69.8 1.1277 1.1243 1.1205 1.116317 1.126 16.3 0.

21、833 8.6 1.598 9.40 11.951 70.3 1.1359 1.1323 1.1284 1.124118 1.134 17.2 0.826 6.6 1.705 9.47 12.744 70.8 1.1442 1.1404 1.1363 1.131919 1.142 18.1 0.819 4.5 1.813 9.54 13.547 71.3 1.1535 1.1486 1.1444 1.139820 1.150 19.0 0.813 2.3 1.920 9.60 14.360 71.8 1.1608 1.1568 1.1542 1.147821 1.158 19.9 0.807

22、0.0 2.031 9.67 15.183 72.3 1.1692 1.1651 1.1606 1.155922 1.166 20.8 0.802 2.3 2.143 9.74 16.016 72.8 1.1777 1.1734 1.1688 1.164023 1.175 21.7 0.796 5.1 2.256 9.81 16.854 73.3 1.1862 1.1818 1.1771 1.172124 1.183 22.5 0.791 3.8 2.371 9.88 17.712 73.8 1.1948 1.1902 1.1854 1.180425 1.191 23.4 0.786 16.1

23、 2.488 9.95 18.575 74.325.2 1.200 32.0aMass of commercial NaCl required = (mass of pure NaCl required)/(% purity).bAt 60F.Fig. 5 Specific Heat of Sodium Chloride Brines(adapted from Carrier 1959)Fig. 6 Specific Gravity of Sodium Chloride Brines(adapted from Carrier 1959)31.4 2013 ASHRAE HandbookFund

24、amentalsBrine applications in refrigeration are mainly in industrialmachinery and in skating rinks. Corrosion is the principal problemfor calcium chloride brines, especially in ice-making tanks wheregalvanized iron cans are immersed.Ordinary salt (sodium chloride) is used where contact with calci-um

25、 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 preventfrost formation on coils. In most refrigerating work, the lower freez-ing point of calcium chloride solution makes it more convenient to use.Commercial calc

26、ium 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 extensively. Commercialsodium chloride is available both in crude (rock salt) and refinedgrades. Because magnesium salts tend to form sludge, their pres-

27、ence in sodium or calcium chloride is undesirable.Corrosion InhibitionAll brine systems must be treated to control corrosion and depos-its. Historically, chloride-based brines were maintained at neutralpH and treated with sodium chromate. However, using chromate asa corrosion inhibitor is no longer

28、deemed acceptable because of itsdetrimental environmental effects. Chromate has been placed onhazardous substance lists by several regulatory agencies. For exam-ple, the U.S. Agency for Toxic Substances and Disease Registrys(ATSDR 2011) Priority List of Hazardous Substances ranks hexa-valent chromiu

29、m 17th out of 275 chemicals of concern (based onfrequency, toxicity, and potential for human exposure at NationalPriorities List facilities). Consequently, hexavalent chrome and sev-eral chromates are also listed on several state right-to-know hazard-ous substance lists, including New Jersey, Califo

30、rnia, Minnesota,Pennsylvania and others.Instead of chromate, most brines use a sodium-nitrite-basedinhibitor ranging from approximately 3000 ppm in calcium brinesto 4000 ppm in sodium brines. Other, proprietary organic inhibitorsare also available to mitigate the inherent corrosiveness of brines.Bef

31、ore using any inhibitor package, review federal, state, andlocal regulations concerning the use and disposal of the spent fluids.If the regulations prove too restrictive, an alternative inhibition sys-tem should be considered.INHIBITED GLYCOLSEthylene glycol and propylene glycol, when properly inhib

32、itedfor corrosion control, are used as aqueous-freezing-point depres-sants (antifreeze) and heat transfer media. Their chief attributes aretheir ability to efficiently lower the freezing point of water, their lowvolatility, and their relatively low corrosivity when properly inhib-ited. Inhibited eth

33、ylene glycol solutions have better thermophysicalproperties than propylene glycol solutions, especially at lower tem-peratures. However, the less toxic propylene glycol is preferred forapplications involving possible human contact or where mandatedby regulations.Physical PropertiesEthylene glycol an

34、d propylene glycol are colorless, practicallyodorless liquids that are miscible with water and many organic com-pounds. Table 3 shows properties 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 thatinc

35、reasing the concentration of ethylene glycol above 60% by massFig. 7 Viscosity of Sodium Chloride Brines(adapted from Carrier 1959)Fig. 8 Thermal Conductivity of Sodium Chloride Brines(adapted from Carrier 1959)Table 3 Physical Properties of Ethylene Glycol and Propylene GlycolPropertyEthylene Glyco

36、lPropylene GlycolMolecular weight 62.07 76.10Ratio of mass to water at 68/68F 1.1155 1.0381Density at 68Flb/ft369.50 64.68lb/gal 9.29 8.65Boiling point, Fat 760 mm Hg 388 369at 50 mm Hg 253 241at 10 mm Hg 192 185Vapor pressure at 68F, mm Hg 0.05 0.07Freezing point, F 9.1 Sets to glass below 60FVisco

37、sity, lb/fthat 32F 138.9 587.8at 68F 50.6 146.4at 104F 23.0 43.5Refractive index nDat 68F 1.4319 1.4329Specific heat at 68F, Btu/lbF 0.561 0.593Heat of fusion at 9.1F, Btu/lb 80.5 Heat of vaporization at 1 atm, Btu/lb 364 296Heat of combustion at 68F, Btu/lb 8,280 10,312Sources: Dow Chemical (2001a,

38、 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, propylene glycol solutions supercool and be-come a glass (a liquid with extremely high vis

39、cosity 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 freezing; on theconcentrated side, solid glycol separates from solution on freezing.The freezi

40、ng 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 ethylene glycolcan be found in Tables 6 to 9 and Figures 9 to 12; similar data foraqueous solut

41、ions 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. Typical corrosion inhibitor packages do notsignificantly affect other physical properties. Phy

42、sical 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 Glycol (vol. %)(Dow Chemical 2001b)Fig. 11 Thermal Conductivity of Aqueous Solutions of Industri

43、ally 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 Industrially Inhibited Propylene Glycol (vol. %)(Dow Chemical 2001b)31.6 2013 ASHRAE Handboo

44、kFundamentalsTable 4 Freezing and Boiling Points of Aqueous Solutions of Ethylene GlycolPercent Ethylene GlycolFreezing Point, FBoiling Point, Fat 14.7 psiaBy Mass By Volume0.0 0.0 32.0 2125.0 4.4 29.4 21310.0 8.9 26.2 21415.0 13.6 22.2 21520.0 18.1 17.9 21621.0 19.2 16.8 21622.0 20.1 15.9 21623.0 2

45、1.0 14.9 21724.0 22.0 13.7 21725.0 22.9 12.7 21826.0 23.9 11.4 21827.0 24.8 10.4 21828.0 25.8 9.2 21929.0 26.7 8.0 21930.0 27.7 6.7 22031.0 28.7 5.4 22032.0 29.6 4.2 22033.0 30.6 2.9 22034.0 31.6 1.4 22035.0 32.6 0.2 22136.0 33.5 1.5 22137.0 34.5 3.0 22138.0 35.5 4.5 22139.0 36.5 6.4 22140.0 37.5 8.

46、1 22241.0 38.5 9.8 22242.0 39.5 11.7 22243.0 40.5 13.5 22344.0 41.5 15.5 22345.0 42.5 17.5 22446.0 43.5 19.8 22447.0 44.5 21.6 22448.0 45.5 23.9 22449.0 46.6 26.7 22450.0 47.6 28.9 22551.0 48.6 31.2 22552.0 49.6 33.6 22553.0 50.6 36.2 22654.0 51.6 38.8 22655.0 52.7 42.0 22756.0 53.7 44.7 22757.0 54.

47、7 47.5 22858.0 55.7 50.0 22859.0 56.8 52.7 22960.0 57.8 54.9 23065.0 62.8 * 23570.0 68.3 * 24275.0 73.6 * 24880.0 78.9 52.2 25585.0 84.3 34.5 27390.0 89.7 21.6 28595.0 95.0 3.0 317Source: Dow Chemical (2001b)*Freezing points are below 60F.Table 5 Freezing and Boiling Points of Aqueous Solutions of P

48、ropylene GlycolPercent Propylene GlycolFreezing Point, FBoiling Point, Fat 14.7 psiaBy Mass By Volume0.0 0.0 32.0 2125.0 4.8 29.1 21210.0 9.6 26.1 21215.0 14.5 22.9 21220.0 19.4 19.2 21321.0 20.4 18.3 21322.0 21.4 17.6 21323.0 22.4 16.6 21324.0 23.4 15.6 21325.0 24.4 14.7 21426.0 25.3 13.7 21427.0 2

49、6.4 12.6 21428.0 27.4 11.5 21529.0 28.4 10.4 21530.0 29.4 9.2 21631.0 30.4 7.9 21632.0 31.4 6.6 21633.0 32.4 5.3 21634.0 33.5 3.9 21635.0 34.4 2.4 21736.0 35.5 0.8 21737.0 36.5 0.8 21738.0 37.5 2.4 21839.0 38.5 4.2 21840.0 39.6 6.0 21941.0 40.6 7.8 21942.0 41.6 9.8 21943.0 42.6 11.8 21944.0 43.7 13.9 21945.0 44.7 16.1 22046.0 45.7 18.3 22047.0 46.8 20.7 22048.0 47.8 23.1 22149.0 48.9 25.7 22150.0 49.9 28.3 22251.0 50.9 31.0 22252.0 51.9 33.8 22253.0 53.0 36.7 22354.