42540_31 - CHAPTER 31 PHYSICAL PROPERTIES OF SECONDARY...

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Unformatted text preview: CHAPTER 31 PHYSICAL PROPERTIES OF SECONDARY COOLANTS (BRINES) Brines ............................................................................................................................................ 31.1 Inhibited Glycols ........................................................................................................................... 31.4 Halocarbons ................................................................................................................................ 31.12 Nonhalocarbon, Nonaqueous Fluids .......................................................................................... 31.13 N many refrigeration applications, heat is transferred to a secondary coolant, which can be any liquid cooled by the refrigerant and used to transfer heat without changing state. These liquids are also known as heat transfer fluids , brines, or secondary refrigerants. Other ASHRAE Handbook volumes describe various applications for secondary coolants. In the 2006 ASHRAE Handbook— Refrigeration, refrigeration systems are discussed in Chapter 4, their uses in food processing in Chapters 14 to 29, and ice rinks in Chapter 35. In the 2007 ASHRAE Handbook—HVAC Applications, solar energy use is discussed in Chapter 33, thermal storage in Chapter 34, and snow melting and freeze protection in Chapter 50. This chapter describes physical properties of several secondary coolants and provides information on their use. Additional, less widely used secondary coolants such as ethyl alcohol or potassium formate are not included in this chapter, but their physical properties are summarized in Melinder (2007). The chapter also includes Table 1 Pure CaCl2, % by Mass 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 29.87 30 32 34 Ratio of Mass to Water at 60°F 1.000 1.044 1.050 1.060 1.069 1.078 1.087 1.096 1.105 1.114 1.124 1.133 1.143 1.152 1.162 1.172 1.182 1.192 1.202 1.212 1.223 1.233 1.244 1.254 1.265 1.276 1.290 1.295 1.317 1.340 Relative Density, Degrees Bauméc 0.0 6.1 7.0 8.2 9.3 10.4 11.6 12.6 13.8 14.8 15.9 16.9 18.0 19.1 20.2 21.3 22.1 23.0 24.4 25.5 26.4 27.4 28.3 29.3 30.4 31.4 32.6 33.0 34.9 36.8 I information on corrosion protection. Additional information on corrosion inhibition can be found in Chapter 48 of the 2007 ASHRAE Handbook—HVAC Applications and Chapter 4 of the 2006 ASHRAE Handbook—Refrigeration. BRINES Physical Properties Water solutions of calcium chloride and sodium chloride are the most common refrigeration brines. Tables 1 and 2 list the properties of pure calcium chloride brine and sodium chloride brine. For commercial grades, use the formulas in the footnotes to these tables. For calcium chloride brines, Figure 1 shows specific heat, Figure 2 shows the ratio of mass of solution to that of water, Figure 3 shows viscosity, and Figure 4 shows thermal conductivity. Figures 5 to 8 show the same properties for sodium chloride brines. Properties of Pure Calcium Chloridea Brines Mass per Unit Volumeb at 60°F CaCl2, lb/gal 0.000 0.436 0.526 0.620 0.714 0.810 0.908 1.006 1.107 1.209 1.313 1.418 1.526 1.635 1.747 1.859 1.970 2.085 2.208 2.328 2.451 2.574 2.699 2.827 2.958 3.090 3.16 3.22 3.49 3.77 Brine, lb/gal 8.34 8.717 8.760 8.851 8.926 9.001 9.076 9.143 9.227 9.302 9.377 9.452 9.536 9.619 9.703 9.786 9.853 9.928 10.037 10.120 10.212 10.295 10.379 10.471 10.563 10.655 10.75 10.80 10.98 11.17 CaCl2, lb/ft3 0.00 3.26 3.93 4.63 5.34 6.05 6.78 7.52 8.27 9.04 9.81 10.60 11.40 12.22 13.05 13.90 14.73 15.58 16.50 17.40 18.32 19.24 20.17 21.13 22.10 23.09 23.65 24.06 26.10 28.22 cAt Specific Heat at Crystalli60°F, zation Btu/lb·°F Starts, °F 1.000 0.924 0.914 0.898 0.884 0.869 0.855 0.842 0.828 0.816 0.804 0.793 0.779 0.767 0.756 0.746 0.737 0.729 0.716 0.707 0.697 0.689 0.682 0.673 0.665 0.658 0.655 0.653 0.640 0.630 32.0 27.7 26.8 25.9 24.6 23.5 22.3 20.8 19.3 17.6 15.5 13.5 11.2 8.6 5.9 2.8 –0.4 –3.9 –7.8 –11.9 –16.2 –21.0 –25.8 –31.2 –37.8 –49.4 –67.0 –50.8 –19.5 4.3 Brine, lb/ft3 62.40 65.15 65.52 66.14 66.70 67.27 67.83 68.33 68.95 69.51 70.08 70.64 71.26 71.89 72.51 73.13 73.63 74.19 75.00 75.63 76.32 76.94 77.56 78.25 78.94 79.62 80.45 80.76 82.14 83.57 bMass Ratio of Mass at Various Temperatures to Water at 60°F 4°F 14°F 32°F 1.043 1.052 1.061 1.071 1.080 1.089 1.098 1.108 1.117 1.127 1.137 1.146 1.156 1.166 1.176 1.186 1.207 1.228 50°F 1.042 1.051 1.060 1.069 1.078 1.087 1.096 1.105 1.115 1.124 1.134 1.143 1.153 1.163 1.173 1.183 1.203 1.224 1.139 1.149 1.159 1.169 1.180 1.190 1.215 1.236 1.211 1.232 Source: CCI (1953) aMass of Type 1 (77% min.) CaCl = (mass of pure CaCl )/(0.77). Mass of Type 2 (94% min.) 2 2 CaCl2 = (mass of pure CaCl2)/(0.94). of water per unit volume = Brine mass minus CaCl2 mass. 60°F. The preparation of this chapter is assigned to TC 3.1, Refrigerants and Secondary Coolants. 31.1 31.2 Fig. 1 Specific Heat of Calcium Chloride Brines Fig. 3 2009 ASHRAE Handbook—Fundamentals Viscosity of Calcium Chloride Brines Fig. 3 Viscosity of Calcium Chloride Brines (CCI 1953) Fig. 1 Specific Heat of Calcium Chloride Brines (CCI 1953) Fig. 2 Specific Gravity of Calcium Chloride Brines Fig. 4 Thermal Conductivity of Calcium Chloride Brines Fig. 2 Specific Gravity of Calcium Chloride Brines (CCI 1953) Fig. 4 Thermal Conductivity of Calcium Chloride Brines (CCI 1953) Physical Properties of Secondary Coolants (Brines) Table 2 Pure NaCl, % by Mass 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 25.2 aMass 31.3 Properties of Pure Sodium Chloridea Brines Mass per Unit Volume at 60°F Ratio of Mass at Various Temperatures to Water at 60°F 14°F 32°F 1.0382 1.0459 1.0536 1.0613 1.0691 1.0769 1.0849 1.0925 1.1004 1.1083 1.1163 1.1243 1.1323 1.1404 1.1486 1.1568 1.1651 1.1734 1.1818 1.1902 50°F 1.0366 1.0440 1.0515 1.0590 1.0665 1.0741 1.0817 1.0897 1.0933 1.1048 1.1126 1.1205 1.1284 1.1363 1.1444 1.1542 1.1606 1.1688 1.1771 1.1854 68°F 1.0341 1.0413 1.0486 1.0559 1.0633 1.0707 1.0782 1.0857 1.0971 1.1009 1.1086 1.1163 1.1241 1.1319 1.1398 1.1478 1.1559 1.1640 1.1721 1.1804 Ratio of Mass to Water at 59°F 1.000 1.035 1.043 1.050 1.057 1.065 1.072 1.080 1.087 1.095 1.103 1.111 1.118 1.126 1.134 1.142 1.150 1.158 1.166 1.175 1.183 1.191 1.200 Relative Density, Degrees Bauméb 0.0 5.1 6.1 7.0 8.0 9.0 10.1 10.8 11.8 12.7 13.6 14.5 15.4 16.3 17.2 18.1 19.0 19.9 20.8 21.7 22.5 23.4 Specific Heat at 59°F, Btu/lb·°F 1.000 0.938 0.927 0.917 0.907 0.897 0.888 0.879 0.870 0.862 0.854 0.847 0.840 0.833 0.826 0.819 0.813 0.807 0.802 0.796 0.791 0.786 Crystallization Starts, °F 32.0 26.7 25.5 24.3 23.0 21.6 20.2 18.8 17.3 15.7 14.0 12.3 10.5 8.6 6.6 4.5 2.3 0.0 –2.3 –5.1 3.8 16.1 32.0 NaCl, lb/gal 0.000 0.432 0.523 0.613 0.706 0.800 0.895 0.992 1.090 1.188 1.291 1.392 1.493 1.598 1.705 1.813 1.920 2.031 2.143 2.256 2.371 2.488 Brine, lb/gal 8.34 8.65 8.71 8.76 8.82 8.89 8.95 9.02 9.08 9.14 9.22 9.28 9.33 9.40 9.47 9.54 9.60 9.67 9.74 9.81 9.88 9.95 bAt NaCl, lb/ft3 0.000 3.230 3.906 4.585 5.280 5.985 6.690 7.414 8.136 8.879 9.632 10.395 11.168 11.951 12.744 13.547 14.360 15.183 16.016 16.854 17.712 18.575 Brine, lb/ft3 62.4 64.6 65.1 65.5 66.0 66.5 66.9 67.4 67.8 68.3 68.8 69.3 69.8 70.3 70.8 71.3 71.8 72.3 72.8 73.3 73.8 74.3 1.1195 1.1277 1.1359 1.1442 1.1535 1.1608 1.1692 1.1777 1.1862 1.1948 of commercial NaCl required = (mass of pure NaCl required)/(% purity). 60°F. Fig. 6 Specific Gravity of Sodium Chloride Brines Fig. 5 Specific Heat of Sodium Chloride Brines 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 Brine applications in refrigeration are mainly in industrial machinery and in skating rinks. Corrosion is the principal problem for calcium chloride brines, especially in ice-making tanks where galvanized iron cans are immersed. Ordinary salt (sodium chloride) is used where contact with calcium chloride is intolerable (e.g., the brine fog method of freezing fish and other foods). It is used as a spray to air-cool unit coolers to prevent frost formation on coils. In most refrigerating work, the lower freezing point of calcium chloride solution makes it more convenient to use. Commercial calcium chloride, available as Type 1 (77% minimum) and Type 2 (94% minimum), is marketed in flake, solid, and solution forms; flake form is used most extensively. Commercial sodium chloride is available both in crude (rock salt) and refined grades. Because magnesium salts tend to form sludge, their presence in sodium or calcium chloride is undesirable. 2009 ASHRAE Handbook—Fundamentals pH and treated with sodium chromate. However, using chromate as a corrosion inhibitor is no longer deemed acceptable because of its environmental effect. Instead, most brines use a sodium-nitritebased inhibitor ranging from approximately 3000 ppm in calcium brines to 4000 ppm in sodium brines. Other, proprietary organic inhibitors are also available to mitigate the inherent corrosiveness of brines. Before using any inhibitor package, review federal, state, and local regulations concerning the use and disposal of the spent fluids. If the regulations prove too restrictive, an alternative inhibition system should be considered. INHIBITED GLYCOLS Ethylene glycol and propylene glycol, when properly inhibited for corrosion control, are used as aqueous-freezing-point depressants (antifreeze) and heat transfer media. Their chief attributes are their ability to efficiently lower the freezing point of water, their low volatility, and their relatively low corrosivity when properly inhibited. Inhibited ethylene glycol solutions have better thermophysical properties than propylene glycol solutions, especially at lower temperatures. However, the less toxic propylene glycol is preferred for applications involving possible human contact or where mandated by regulations. Corrosion Inhibition All brine systems must be treated to control corrosion and deposits. Historically, chloride-based brines were maintained at neutral Fig. 7 Viscosity of Sodium Chloride Brines Physical Properties Ethylene glycol and propylene glycol are colorless, practically odorless liquids that are miscible with water and many organic compounds. Table 3 shows properties of the pure materials. The freezing and boiling points of aqueous solutions of ethylene glycol and propylene glycol are given in Tables 4 and 5. Note that increasing the concentration of ethylene glycol above 60% by mass causes the freezing point of the solution to increase. Propylene glycol solutions above 60% by mass do not have freezing points. Instead of freezing, propylene glycol solutions supercool and become a glass (a liquid with extremely high viscosity and the appearance and properties of a noncrystalline amorphous solid). On the dilute side of the eutectic (the mixture at which freezing produces a solid phase of the same composition), ice forms on freezing; on the concentrated side, solid glycol separates from solution on freezing.The Table 3 Physical Properties of Ethylene Glycol and Propylene Glycol Property Molecular weight Ratio of mass to water at 68/68°F Density at 68°F lb/ft3 lb/gal Boiling point, °F at 760 mm Hg at 50 mm Hg at 10 mm Hg Vapor pressure at 68°F, mm Hg Freezing point, °F Viscosity, lb/ft·h at 32°F at 68°F at 104°F Refractive index nD at 68°F Specific heat at 68°F, Btu/lb·°F Heat of fusion at 9.1°F, Btu/lb Heat of vaporization at 1 atm, Btu/lb Heat of combustion at 68°F, Btu/lb Sources: Dow Chemical (2001a, 2001b) Ethylene Glycol 62.07 1.1155 69.50 9.29 388 253 192 0.05 9.1 Propylene Glycol 76.10 1.0381 64.68 8.65 369 241 185 0.07 Sets to glass below 60°F 587.8 146.4 43.5 1.4329 0.593 — 296 10,312 Fig. 7 Viscosity of Sodium Chloride Brines (adapted from Carrier 1959) Fig. 8 Thermal Conductivity of Sodium Chloride Brines Fig. 8 Thermal Conductivity of Sodium Chloride Brines (adapted from Carrier 1959) 138.9 50.6 23.0 1.4319 0.561 80.5 364 8,280 Physical Properties of Secondary Coolants (Brines) Table 4 Freezing and Boiling Points of Aqueous Solutions of Ethylene Glycol By Volume 0.0 4.4 8.9 13.6 18.1 19.2 20.1 21.0 22.0 22.9 23.9 24.8 25.8 26.7 27.7 28.7 29.6 30.6 31.6 32.6 33.5 34.5 35.5 36.5 37.5 38.5 39.5 40.5 41.5 42.5 43.5 44.5 45.5 46.6 47.6 48.6 49.6 50.6 51.6 52.7 53.7 54.7 55.7 56.8 57.8 62.8 68.3 73.6 78.9 84.3 89.7 95.0 Freezing Point, °F 32.0 29.4 26.2 22.2 17.9 16.8 15.9 14.9 13.7 12.7 11.4 10.4 9.2 8.0 6.7 5.4 4.2 2.9 1.4 –0.2 –1.5 –3.0 –4.5 –6.4 –8.1 –9.8 –11.7 –13.5 –15.5 –17.5 –19.8 –21.6 –23.9 –26.7 –28.9 –31.2 –33.6 –36.2 –38.8 –42.0 –44.7 –47.5 –50.0 –52.7 –54.9 * * * –52.2 –34.5 –21.6 –3.0 Boiling Point, °F at 14.7 psia 212 213 214 215 216 216 216 217 217 218 218 218 219 219 220 220 220 220 220 221 221 221 221 221 222 222 222 223 223 224 224 224 224 224 225 225 225 226 226 227 227 228 228 229 230 235 242 248 255 273 285 317 31.5 Table 5 Freezing and Boiling Points of Aqueous Solutions of Propylene Glycol By Volume 0.0 4.8 9.6 14.5 19.4 20.4 21.4 22.4 23.4 24.4 25.3 26.4 27.4 28.4 29.4 30.4 31.4 32.4 33.5 34.4 35.5 36.5 37.5 38.5 39.6 40.6 41.6 42.6 43.7 44.7 45.7 46.8 47.8 48.9 49.9 50.9 51.9 53.0 54.0 55.0 56.0 57.0 58.0 59.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 95.0 Freezing Point, °F 32.0 29.1 26.1 22.9 19.2 18.3 17.6 16.6 15.6 14.7 13.7 12.6 11.5 10.4 9.2 7.9 6.6 5.3 3.9 2.4 0.8 –0.8 –2.4 –4.2 –6.0 –7.8 –9.8 –11.8 –13.9 –16.1 –18.3 –20.7 –23.1 –25.7 –28.3 –31.0 –33.8 –36.7 –39.7 –42.8 –46.0 –49.3 –52.7 –56.2 –59.9 * * * * * * * Boiling Point, °F at 14.7 psia 212 212 212 212 213 213 213 213 213 214 214 214 215 215 216 216 216 216 216 217 217 217 218 218 219 219 219 219 219 220 220 220 221 221 222 222 222 223 223 223 223 224 224 224 225 227 230 237 245 257 270 310 Percent Ethylene Glycol By Mass 0.0 5.0 10.0 15.0 20.0 21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 31.0 32.0 33.0 34.0 35.0 36.0 37.0 38.0 39.0 40.0 41.0 42.0 43.0 44.0 45.0 46.0 47.0 48.0 49.0 50.0 51.0 52.0 53.0 54.0 55.0 56.0 57.0 58.0 59.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 95.0 Percent Propylene Glycol By Mass 0.0 5.0 10.0 15.0 20.0 21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 31.0 32.0 33.0 34.0 35.0 36.0 37.0 38.0 39.0 40.0 41.0 42.0 43.0 44.0 45.0 46.0 47.0 48.0 49.0 50.0 51.0 52.0 53.0 54.0 55.0 56.0 57.0 58.0 59.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 95.0 Source: Dow Chemical (2001b) *Freezing points are below –60°F. Source: Dow Chemical (2001a) *Above 60% by mass, solutions do not freeze but become a glass. 31.6 Fig. 9 Density of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %) 2009 ASHRAE Handbook—Fundamentals Fig. 11 Thermal Conductivity of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %) Fig. 11 Thermal Conductivity of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %) (Dow Chemical 2001b) Fig. 9 Density of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %) (Dow Chemical 2001b) Fig. 12 Viscosity of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %) Fig. 10 Specific Heat of Aqueous Solutions of Industrially Inhibited Ethylene Glycol (vol. %) Fig. 12 Viscosity 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. 13 Density of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) 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 conductivity, and viscosity) for aqueous solutions of ethylene glycol can be found in Tables 6 to 9 and Figures 9 to 12; similar data for aqueous solutions of propylene glycol are in Tables 10 to 13 and Figures 13 to 16. Densities are for aqueous solutions of industrially inhibited glycols, and are somewhat higher than those for pure glycol and water alone. Typical corrosion inhibitor packages do not significantly affect other physical properties. Physical properties for the two fluids are similar, except for viscosity. At the same concentration, aqueous solutions of propylene glycol are more viscous than solutions of ethylene glycol. This higher viscosity accounts for the majority of the performance difference between the two fluids. The choice of glycol concentration depends on the type of protection required by the application. If the fluid is being used to prevent equipment damage during idle periods in cold weather, such as winterizing coils in an HVAC system, 30% by volume ethylene glycol or 35% by volume propylene glycol is sufficient. These Fig. 13 Density of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) (Dow Chemical 2001b) Physical Properties of Secondary Coolants (Brines) Table 6 Density of Aqueous Solutions of Ethylene Glycol Concentrations in Volume Percent Ethylene Glycol Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Source: Dow Chemical (2001b) 31.7 10% 20% 30% 40% 50% 68.12 68.05 67.98 67.90 67.80 67.70 67.59 67.47 67.34 67.20 67.05 66.90 66.73 66.55 66.37 66.17 65.97 65.75 65.53 65.30 65.05 64.80 64.54 64.27 63.99 63.70 63.40 63.10 62.78 Note: Density in lb/ft3. 60% 69.03 68.96 68.87 68.78 68.67 68.56 68.44 68.31 68.17 68.02 67.86 67.69 67.51 67.32 67.13 66.92 66.71 66.48 66.25 66.00 65.75 65.49 65.21 64.93 64.64 64.34 64.03 63.71 63.39 70% 69.90 69.82 69.72 69.62 69.50 69.38 69.25 69.10 68.95 68.79 68.62 68.44 68.25 68.05 67.84 67.63 67.40 67.16 66.92 66.66 66.40 66.12 65.84 65.55 65.24 64.93 64.61 64.28 63.94 80% 70.75 70.65 70.54 70.43 70.30 70.16 70.02 69.86 69.70 69.53 69.35 69.15 68.95 68.74 68.52 68.29 68.05 67.81 67.55 67.28 67.01 66.72 66.42 66.12 65.81 65.48 65.15 64.81 64.46 90% 71.45 71.33 71.20 71.06 70.92 70.76 70.59 70.42 70.23 70.04 69.83 69.62 69.40 69.17 68.92 68.67 68.41 68.14 67.86 67.58 67.28 66.97 66.65 66.33 65.99 65.65 65.29 64.93 63.69 63.61 63.52 63.42 63.31 63.19 63.07 62.93 62.79 62.63 62.47 62.30 62.11 61.92 61.72 61.51 61.29 61.06 60.82 60.57 60.31 60.05 59.77 64.83 64.75 64.66 64.56 64.45 64.33 64.21 64.07 63.93 63.77 63.61 63.43 63.25 63.06 62.86 62.64 62.42 62.19 61.95 61.71 61.45 61.18 60.90 60.62 65.93 65.85 65.76 65.66 65.55 65.43 65.30 65.17 65.02 64.86 64.70 64.52 64.34 64.15 63.95 63.73 63.51 63.28 63.04 62.79 62.53 62.27 61.99 61.70 61.40 67.04 66.97 66.89 66.80 66.70 66.59 66.47 66.34 66.20 66.05 65.90 65.73 65.56 65.37 65.18 64.98 64.76 64.54 64.31 64.07 63.82 63.56 63.29 63.01 62.72 62.43 62.12 Table 7 Specific Heat of Aqueous Solutions of Ethylene Glycol Concentrations in Volume Percent Ethylene Glycol Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Source: Dow Chemical (2001b) 10% 20% 30% 40% 50% 0.734 0.739 0.744 0.749 0.754 0.759 0.765 0.770 0.775 0.780 0.785 0.790 0.795 0.800 0.806 0.811 0.816 0.821 0.826 0.831 0.836 0.842 0.847 0.852 0.857 0.862 0.867 0.872 0.877 60% 0.680 0.686 0.692 0.698 0.703 0.709 0.715 0.721 0.727 0.732 0.738 0.744 0.750 0.756 0.761 0.767 0.773 0.779 0.785 0.790 0.796 0.802 0.808 0.813 0.819 0.825 0.831 0.837 0.842 70% 0.625 0.631 0.638 0.644 0.651 0.657 0.664 0.670 0.676 0.683 0.689 0.696 0.702 0.709 0.715 0.721 0.728 0.734 0.741 0.747 0.754 0.760 0.766 0.773 0.779 0.786 0.792 0.799 0.805 80% 0.567 0.574 0.581 0.588 0.595 0.603 0.610 0.617 0.624 0.631 0.638 0.645 0.652 0.659 0.666 0.673 0.680 0.687 0.694 0.702 0.709 0.716 0.723 0.730 0.737 0.744 0.751 0.758 0.765 90% 0.515 0.523 0.530 0.538 0.546 0.553 0.561 0.569 0.576 0.584 0.592 0.600 0.607 0.615 0.623 0.630 0.638 0.646 0.654 0.661 0.669 0.677 0.684 0.692 0.700 0.708 0.715 0.723 0.940 0.943 0.945 0.947 0.950 0.952 0.954 0.957 0.959 0.961 0.964 0.966 0.968 0.971 0.973 0.975 0.978 0.980 0.982 0.985 0.987 0.989 0.992 0.897 0.900 0.903 0.906 0.909 0.912 0.915 0.918 0.922 0.925 0.928 0.931 0.934 0.937 0.940 0.943 0.946 0.949 0.952 0.955 0.958 0.961 0.964 0.967 0.849 0.853 0.857 0.861 0.864 0.868 0.872 0.876 0.880 0.883 0.887 0.891 0.895 0.898 0.902 0.906 0.910 0.913 0.917 0.921 0.925 0.929 0.932 0.936 0.940 0.794 0.799 0.803 0.808 0.812 0.816 0.821 0.825 0.830 0.834 0.839 0.843 0.848 0.852 0.857 0.861 0.865 0.870 0.874 0.879 0.883 0.888 0.892 0.897 0.901 0.905 0.910 Note: Specific heat in Btu/lb·°F. 31.8 2009 ASHRAE Handbook—Fundamentals Table 8 Thermal Conductivity of Aqueous Solutions of Ethylene Glycol Concentrations in Volume Percent Ethylene Glycol Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 10% 20% 30% 40% 50% 0.187 0.190 0.192 0.195 0.198 0.200 0.203 0.205 0.208 0.210 0.212 0.214 0.216 0.218 0.220 0.221 0.223 0.224 0.225 0.226 0.227 0.228 0.228 0.229 0.229 0.230 0.230 0.230 0.230 60% 0.173 0.175 0.178 0.180 0.182 0.184 0.186 0.188 0.190 0.191 0.193 0.195 0.196 0.198 0.199 0.200 0.201 0.202 0.203 0.204 0.204 0.205 0.206 0.206 0.206 0.207 0.207 0.207 0.207 70% 0.161 0.163 0.165 0.166 0.168 0.169 0.171 0.172 0.174 0.175 0.177 0.178 0.179 0.180 0.181 0.182 0.183 0.183 0.184 0.185 0.185 0.186 0.186 0.186 0.186 0.187 0.187 0.187 0.187 80% 0.151 0.153 0.154 0.155 0.156 0.158 0.159 0.160 0.161 0.162 0.163 0.164 0.164 0.165 0.166 0.167 0.167 0.168 0.168 0.169 0.169 0.169 0.170 0.170 0.170 0.170 0.170 0.170 0.170 90% 0.145 0.146 0.147 0.148 0.148 0.149 0.150 0.151 0.151 0.152 0.153 0.153 0.154 0.154 0.155 0.155 0.156 0.156 0.156 0.157 0.157 0.157 0.157 0.157 0.157 0.157 0.157 0.157 0.294 0.300 0.305 0.310 0.314 0.319 0.323 0.327 0.331 0.334 0.337 0.340 0.342 0.345 0.347 0.349 0.350 0.351 0.352 0.353 0.354 0.355 0.355 0.263 0.268 0.273 0.277 0.281 0.285 0.289 0.292 0.296 0.299 0.301 0.304 0.306 0.309 0.310 0.312 0.314 0.315 0.316 0.317 0.318 0.318 0.319 0.319 0.236 0.240 0.244 0.248 0.251 0.255 0.258 0.261 0.264 0.267 0.269 0.272 0.274 0.276 0.277 0.279 0.280 0.282 0.283 0.284 0.284 0.285 0.285 0.286 0.286 0.209 0.213 0.216 0.219 0.222 0.225 0.228 0.231 0.234 0.236 0.239 0.241 0.243 0.245 0.247 0.248 0.250 0.251 0.252 0.253 0.254 0.255 0.255 0.256 0.256 0.256 0.257 Source: Dow Chemical (2001b) Note: Thermal conductivity in Btu·ft/h·ft2 ·°F. Table 9 Viscosity of Aqueous Solutions of Ethylene Glycol Concentrations in Volume Percent Ethylene Glycol Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Source: Dow Chemical (2001b) 10% 20% 30% 40% 50% 154.07 97.68 65.97 46.79 34.50 26.25 20.51 16.38 13.30 11.01 9.22 7.81 6.68 5.78 5.03 4.40 3.89 3.46 3.10 2.78 2.52 2.27 2.06 1.89 1.72 1.60 1.45 1.35 1.26 60% 216.92 146.26 101.72 72.77 53.37 40.06 30.67 23.95 18.99 15.31 12.51 10.35 8.66 7.33 6.24 5.39 4.67 4.09 3.60 3.19 2.85 2.56 2.30 2.08 1.89 1.74 1.60 1.48 1.35 70% 311.55 217.55 153.61 110.26 80.58 59.97 45.41 34.96 27.36 21.70 17.47 14.22 11.73 9.77 8.22 6.97 5.98 5.15 4.50 3.94 3.46 3.07 2.76 2.47 2.23 2.01 1.84 1.67 1.52 80% 448.06 317.67 222.27 157.34 113.43 83.41 62.51 47.68 36.99 29.15 23.27 18.84 15.43 12.77 10.67 9.02 7.67 6.58 5.68 4.96 4.35 3.82 3.39 3.02 2.71 2.44 2.20 2.01 1.81 90% 688.18 410.83 260.71 173.86 120.81 86.87 64.32 48.82 37.86 29.92 24.02 19.59 16.16 13.50 11.39 9.70 8.35 7.21 6.29 5.52 4.86 4.33 3.87 3.46 3.12 2.81 2.56 2.32 5.23 4.40 3.77 3.27 2.85 2.52 2.25 2.01 1.81 1.64 1.50 1.38 1.28 1.19 1.11 1.04 0.97 0.90 0.85 0.80 0.77 0.73 0.70 9.43 7.60 6.27 5.27 4.50 3.89 3.41 3.00 2.69 2.39 2.18 1.96 1.79 1.64 1.52 1.40 1.31 1.21 1.14 1.04 0.99 0.92 0.87 0.82 16.52 13.01 10.47 8.56 7.14 6.02 5.15 4.45 3.87 3.41 3.02 2.69 2.42 2.18 1.98 1.81 1.64 1.52 1.40 1.31 1.21 1.11 1.04 0.97 0.92 47.37 33.29 24.51 18.72 14.73 11.88 9.77 8.18 6.94 5.95 5.15 4.52 3.97 3.53 3.14 2.83 2.54 2.30 2.10 1.91 1.77 1.62 1.48 1.38 1.28 1.19 1.09 Note: Viscosity in ft/lb·h. Physical Properties of Secondary Coolants (Brines) Table 10 Density of Aqueous Solutions of an Industrially Inhibited Propylene Glycol Concentrations in Volume Percent Propylene Glycol Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Source: Dow Chemical (2001a) 31.9 10% 20% 30% 40% 50% 66.46 66.35 66.23 66.11 65.97 65.82 65.67 65.50 65.33 65.14 64.95 64.74 64.53 64.30 64.06 63.82 63.57 63.30 63.03 62.74 62.45 62.14 61.83 61.50 61.17 60.83 60.47 60.11 Note: Density in lb/ft3. 60% 67.05 66.93 66.81 66.68 66.54 66.38 66.22 66.05 65.87 65.68 65.47 65.26 65.04 64.81 64.57 64.32 64.06 63.79 63.51 63.22 62.92 62.61 62.29 61.97 61.63 61.28 60.92 60.55 60.18 70% 67.47 67.34 67.20 67.05 66.89 66.72 66.54 66.35 66.16 65.95 65.73 65.51 65.27 65.03 64.77 64.51 64.23 63.95 63.66 63.35 63.04 62.72 62.39 62.05 61.69 61.33 60.96 60.58 60.19 80% 68.38 68.13 67.87 67.62 67.36 67.10 66.83 66.57 66.30 66.04 65.77 65.49 65.22 64.95 64.67 64.39 64.11 63.83 63.55 63.26 62.97 62.68 62.39 62.10 61.81 61.51 61.21 60.91 60.61 90% 68.25 68.00 67.75 67.49 67.23 66.97 66.71 66.44 66.18 65.91 65.64 65.37 65.09 64.82 64.54 64.26 63.98 63.70 63.42 63.13 62.85 62.56 62.27 61.97 61.68 61.38 61.08 60.78 60.48 63.38 63.30 63.20 63.10 62.98 62.86 62.73 62.59 62.44 62.28 62.11 61.93 61.74 61.54 61.33 61.11 60.89 60.65 60.41 60.15 59.89 59.61 59.33 64.23 64.14 64.03 63.92 63.79 63.66 63.52 63.37 63.20 63.03 62.85 62.66 62.46 62.25 62.03 61.80 61.56 61.31 61.05 60.78 60.50 60.21 59.91 59.60 65.00 64.90 64.79 64.67 64.53 64.39 64.24 64.08 63.91 63.73 63.54 63.33 63.12 62.90 62.67 62.43 62.18 61.92 61.65 61.37 61.08 60.78 60.47 60.15 59.82 65.71 65.60 65.48 65.35 65.21 65.06 64.90 64.73 64.55 64.36 64.16 63.95 63.74 63.51 63.27 63.02 62.76 62.49 62.22 61.93 61.63 61.32 61.00 60.68 60.34 59.99 Table 11 Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Source: Dow Chemical (2001a) Specific Heat of Aqueous Solutions of Propylene Glycol Concentrations in Volume Percent Propylene Glycol 30% 40% 50% 0.799 0.804 0.809 0.814 0.820 0.825 0.830 0.835 0.840 0.845 0.850 0.855 0.861 0.866 0.871 0.876 0.881 0.886 0.891 0.896 0.902 0.907 0.912 0.917 0.922 0.927 0.932 0.937 60% 0.741 0.746 0.752 0.758 0.764 0.770 0.776 0.782 0.787 0.793 0.799 0.805 0.811 0.817 0.823 0.828 0.834 0.840 0.846 0.852 0.858 0.864 0.869 0.875 0.881 0.887 0.893 0.899 0.905 70% 0.680 0.687 0.693 0.700 0.707 0.713 0.720 0.726 0.733 0.740 0.746 0.753 0.760 0.766 0.773 0.779 0.786 0.793 0.799 0.806 0.812 0.819 0.826 0.832 0.839 0.845 0.852 0.859 0.865 80% 0.615 0.623 0.630 0.637 0.645 0.652 0.660 0.667 0.674 0.682 0.689 0.696 0.704 0.711 0.718 0.726 0.733 0.740 0.748 0.755 0.762 0.770 0.777 0.784 0.792 0.799 0.806 0.814 0.821 90% 0.542 0.550 0.558 0.566 0.574 0.583 0.591 0.599 0.607 0.615 0.623 0.631 0.639 0.647 0.656 0.664 0.672 0.680 0.688 0.696 0.704 0.712 0.720 0.729 0.737 0.745 0.753 0.761 0.769 10% 20% 0.966 0.968 0.970 0.972 0.974 0.976 0.979 0.981 0.983 0.985 0.987 0.989 0.991 0.993 0.996 0.998 1.000 1.002 1.004 1.006 1.008 1.011 1.013 0.936 0.938 0.941 0.944 0.947 0.950 0.953 0.956 0.959 0.962 0.965 0.967 0.970 0.973 0.976 0.979 0.982 0.985 0.988 0.991 0.994 0.996 0.999 1.002 0.898 0.902 0.906 0.909 0.913 0.917 0.920 0.924 0.928 0.931 0.935 0.939 0.942 0.946 0.950 0.953 0.957 0.961 0.964 0.968 0.971 0.975 0.979 0.982 0.986 0.855 0.859 0.864 0.868 0.872 0.877 0.881 0.886 0.890 0.894 0.899 0.903 0.908 0.912 0.916 0.921 0.925 0.929 0.934 0.938 0.943 0.947 0.951 0.956 0.960 0.965 Note: Specific heat in Btu/lb·°F. 31.10 Table 12 Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 10% 2009 ASHRAE Handbook—Fundamentals Thermal Conductivity of Aqueous Solutions of Propylene Glycol Concentrations in Volume Percent Propylene Glycol 20% 30% 40% 50% 0.175 0.178 0.181 0.183 0.186 0.188 0.191 0.193 0.195 0.198 0.200 0.202 0.203 0.205 0.206 0.208 0.209 0.210 0.211 0.212 0.213 0.213 0.214 0.214 0.214 0.214 0.214 0.214 60% 0.156 0.158 0.160 0.162 0.164 0.166 0.168 0.170 0.171 0.173 0.175 0.176 0.178 0.179 0.180 0.181 0.183 0.183 0.184 0.185 0.185 0.186 0.186 0.187 0.187 0.187 0.187 0.187 0.187 70% 0.140 0.142 0.143 0.145 0.146 0.148 0.149 0.151 0.152 0.153 0.154 0.155 0.156 0.157 0.158 0.159 0.160 0.160 0.161 0.161 0.162 0.162 0.162 0.162 0.162 0.162 0.162 0.162 0.162 80% 0.127 0.129 0.130 0.131 0.132 0.133 0.134 0.135 0.136 0.137 0.137 0.138 0.139 0.139 0.140 0.140 0.141 0.141 0.142 0.142 0.142 0.142 0.142 0.142 0.142 0.142 0.142 0.142 0.142 90% 0.117 0.118 0.119 0.119 0.120 0.121 0.122 0.122 0.123 0.123 0.124 0.124 0.125 0.125 0.125 0.126 0.126 0.126 0.126 0.126 0.126 0.126 0.126 0.126 0.126 0.126 0.126 0.125 0.125 0.298 0.303 0.308 0.312 0.317 0.321 0.325 0.329 0.332 0.335 0.338 0.340 0.343 0.345 0.347 0.348 0.349 0.350 0.351 0.352 0.353 0.353 0.263 0.267 0.272 0.276 0.280 0.284 0.287 0.291 0.294 0.296 0.299 0.301 0.304 0.305 0.307 0.309 0.310 0.311 0.312 0.313 0.313 0.313 0.314 0.228 0.232 0.236 0.240 0.243 0.247 0.250 0.253 0.256 0.259 0.261 0.264 0.266 0.268 0.270 0.271 0.273 0.274 0.275 0.276 0.276 0.277 0.277 0.277 0.278 0.201 0.205 0.208 0.211 0.214 0.217 0.220 0.223 0.225 0.228 0.230 0.232 0.234 0.236 0.237 0.239 0.240 0.241 0.242 0.243 0.243 0.244 0.244 0.244 0.245 0.245 Source: Dow Chemical (2001a) Note: Thermal conductivity in Btu·ft/h·ft2 ·°F. Table 13 Viscosity of Aqueous Solutions of Propylene Glycol Concentrations in Volume Percent Propylene Glycol Temperature, °F –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 Source: Dow Chemical (2001a) 10% 20% 30% 40% 50% 374.64 230.25 149.55 97.49 66.82 47.22 34.33 25.62 19.57 15.26 12.14 9.82 8.08 6.75 5.71 4.89 4.23 3.70 3.27 2.90 2.59 2.35 2.13 1.96 1.79 1.67 1.55 1.43 60% 1203.67 722.70 442.60 277.95 179.47 119.24 81.47 57.21 41.25 30.46 23.01 17.76 13.96 11.18 9.10 7.52 6.31 5.37 4.62 4.02 3.51 3.12 2.78 2.52 2.27 2.08 1.91 1.77 1.64 70% 2092.20 1194.86 704.63 429.94 271.42 177.13 119.31 82.78 59.05 43.20 32.37 24.80 19.35 15.41 12.46 10.23 8.54 7.21 6.14 5.30 4.62 4.09 3.63 3.24 2.93 2.66 2.42 2.23 2.06 80% 3299.03 1985.06 1199.09 735.26 460.62 295.85 195.12 132.18 91.90 65.56 47.87 35.78 27.31 21.26 16.86 13.60 11.13 9.24 7.79 6.65 5.73 5.01 4.40 3.89 3.51 3.17 2.88 2.64 2.42 90% 8600.39 4402.06 2378.08 1350.63 803.19 498.11 320.94 214.11 147.40 104.41 75.89 56.49 42.94 33.29 26.27 21.07 17.15 14.15 11.83 9.99 8.52 7.35 6.39 5.59 4.93 4.40 3.94 3.56 3.22 6.77 5.52 4.57 3.87 3.34 2.90 2.54 2.25 2.01 1.81 1.64 1.50 1.38 1.26 1.16 1.06 0.99 0.92 0.87 0.82 0.77 0.73 0.68 12.97 10.23 8.25 6.75 5.61 4.72 4.02 3.46 3.02 2.66 2.35 2.10 1.89 1.72 1.55 1.43 1.31 1.21 1.11 1.04 0.97 0.92 0.87 0.82 32.46 23.92 18.05 13.91 10.93 8.76 7.11 5.88 4.93 4.19 3.60 3.14 2.76 2.44 2.20 1.98 1.79 1.64 1.50 1.40 1.31 1.21 1.14 1.06 1.02 98.99 65.29 44.75 31.74 23.22 17.44 13.45 10.60 8.52 6.97 5.81 4.91 4.19 3.63 3.17 2.81 2.52 2.25 2.06 1.86 1.72 1.60 1.48 1.38 1.28 1.21 Note: Viscosity in ft/lb·h. Physical Properties of Secondary Coolants (Brines) Fig. 14 Specific Heat of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) 31.11 Fig. 16 Viscosity of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) Fig. 16 Viscosity of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) (Dow Chemical 2001a) Fig. 14 Specific Heat of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) (Dow Chemical 2001b) Fig. 15 Thermal Conductivity of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) inhibitors that are effective for water-based fluids, but also additional additives to buffer or neutralize the acidic glycol degradation products that form during use. Corrosion inhibitors form a surface barrier that protects metal from attack, but their effectiveness is highly dependent on solution pH. Failure to compensate for glycol degradation leads to a downward shift in solution pH, which negates the usefulness of the corrosion inhibitor at protecting iron-based alloys (particularly cast iron and carbon steels, but also solders). Properly inhibited glycol products are available from several suppliers. Service Considerations Design Considerations. Inhibited glycols can be used at temperatures as high as 350°F. However, maximum-use temperatures vary from fluid to fluid, so the manufacturer’s suggested temperature-use ranges should be followed. In systems with a high degree of aeration, the bulk fluid temperature should not exceed 150°F; however, temperatures up to 350°F are permissible in a pressurized system if air intake is eliminated. Maximum film temperatures should not exceed 50°F above the bulk temperature. Nitrogen blanketing minimizes oxidation when the system operates at elevated temperatures for extended periods. Minimum operating temperatures for a recirculating fluid are typically –20°F for ethylene glycol solutions and 0°F for propylene glycol solutions. Operation below these temperatures is generally impractical, because the fluids’ viscosity builds dramatically, thus increasing pumping horsepower requirements and reducing heat transfer film coefficients. Standard materials can be used with most inhibited glycol solutions, except galvanized metals, which form insoluble zinc salts with the corrosion inhibitors. This depletes corrosion inhibitors below effective limits, and can cause excessive insoluble salt (sludge) formation. Because removal of sludge and other contaminants is critical, install suitable filters. If inhibitors are rapidly and completely adsorbed by such contamination, the fluid is ineffective for corrosion inhibition. Consider such adsorption when selecting filters. Storage and Handling. Inhibited glycol concentrates are stable, relatively noncorrosive materials with high flash points. These fluids can be stored in mild steel, stainless steel, or aluminum vessels. However, aluminum should be used only when the fluid temperature is below 150°F. Corrosion in the vapor space of vessels may be a problem, because the fluid’s inhibitor package cannot reach these surfaces to protect them. A protective coating may be necessary (e.g., novolac-based vinyl ester resins, high-bake phenolic resins, polypropylene, polyvinylidene fluoride). To ensure the coating is suitable for Fig. 15 Thermal Conductivity of Aqueous Solutions of Industrially Inhibited Propylene Glycol (vol. %) (Dow Chemical 2001b) concentrations allow the fluid to freeze. As the fluid freezes, it forms a slush that expands and flows into any available space. Therefore, expansion volume must be included with this type of protection. If the application requires that the fluid remain entirely liquid, use a concentration with a freezing point 5°F below the lowest expected temperature. Avoid excessive glycol concentration because it increases initial cost and adversely affects the fluid’s physical properties. Additional physical property data are available from suppliers of industrially inhibited ethylene and propylene glycol. Corrosion Inhibition Interestingly, ethylene glycol and propylene glycol, when not diluted with water, are actually less corrosive than water is with common construction metals. However, once diluted with water (as is typical), all aqueous glycol solutions are more corrosive than the water from which they are prepared. This is because uninhibited glycols oxidize with use to form acidic degradation products, and become increasingly more corrosive if not properly inhibited. The amount of oxidation is influenced by temperature, degree of aeration, and type of metal components to which the glycol solution is exposed. It is therefore necessary to use not only corrosion 31.12 a particular application and temperature, consult the manufacturer. Because the chemical properties of an inhibited glycol concentrate differ from those of its dilutions, the effect of the concentrate on different containers should be known when selecting storage. Choose transfer pumps only after considering temperature/ viscosity data. Centrifugal pumps with electric motor drives are often used. Materials compatible with ethylene or propylene glycol should be used for pump packing material. Mechanical seals are also satisfactory. Bypass or inline filters are recommended to remove suspended particles, which can abrade seal surfaces. Welded mild steel transfer piping with a minimum diameter is normally used in conjunction with the piping, although flanged and gasketed joints are also satisfactory. Preparation Before Application. Before an inhibited glycol is charged into a system, remove residual contaminants such as sludge, rust, brine deposits, and oil so the newly installed fluid functions properly. Avoid strong acid cleaners; if they are required, consider inhibited acids. Completely remove the cleaning agent before charging with inhibited glycol. Dilution Water. Use distilled, deionized, or condensate water, because water from some sources contains elements that reduce the effectiveness of the inhibited formulation. If water of this quality is unavailable, water containing less than 25 ppm chloride, less than 25 ppm sulfate, and less than 100 ppm of total hardness may be used. Fluid Maintenance. Glycol concentrations can be determined by refractive index, gas chromatography, or Karl Fischer analysis for water (assuming that the concentration of other fluid components, such as inhibitor, is known). Using density to determine glycol concentration is unsatisfactory because (1) density measurements are temperature-sensitive, (2) inhibitor concentrations can change density, (3) values for propylene glycol are close to those of water, and (4) propylene glycol values exhibit a maximum at 70 to 75% concentration. 2009 ASHRAE Handbook—Fundamentals An effective inhibitor monitoring and maintenance schedule is essential to keep a glycol solution relatively noncorrosive for a long period. Inspection immediately after installation, and annually thereafter, is normally an effective practice. Visual inspection of solution and filter residue can often detect potential system problems. Many manufacturers of inhibited glycol-based heat transfer fluids provide analytical service to ensure that their product remains in good condition. This analysis may include some or all of the following: percent of ethylene and/or propylene glycol, freezing point, pH, reserve alkalinity, corrosion inhibitor evaluation, contaminants, total hardness, metal content, and degradation products. If maintenance on the fluid is required, recommendations may be given along with the analysis results. Properly inhibited and maintained glycol solutions provide better corrosion protection than brine solutions in most systems. A long, though not indefinite, service life can be expected. Avoid indiscriminate mixing of inhibited formulations. HALOCARBONS Many common refrigerants are used as secondary coolants as well as primary refrigerants. Their favorable properties as heat transfer fluids include low freezing points, low viscosities, nonflammability, and good stability. Chapters 29 and 30 present physical and thermodynamic properties for common refrigerants. Tables 1 and 2 in Chapter 29 summarizes comparative safety characteristics for halocarbons. ACGIH has more information on halocarbon toxicity threshold limit values and biological exposure indices (see the Bibliography). Construction materials and stability factors in halocarbon use are discussed in Chapter 29 of this volume and Chapter 5 of the 2006 ASHRAE Handbook—Refrigeration. Table 14 Properties of a Polydimethylsiloxane Heat Transfer Fluid Heat Thermal Vapor Temperature, Pressure, Viscosity, Density, Capacity, Conductivity, °F psia lb/ft·h lb/ft3 Btu/lb·°F Btu/h·ft·°F –100 –90 –80 –70 –60 –50 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.02 0.03 0.04 0.05 0.08 0.11 0.15 0.20 0.27 0.35 0.46 0.60 0.76 0.96 1.20 30.24 25.40 21.34 18.14 15.55 13.43 11.68 10.21 9.00 7.96 7.09 6.34 5.71 5.15 4.67 4.26 3.87 3.56 3.27 3.02 2.78 2.59 2.40 2.24 2.09 1.96 1.84 1.73 1.63 1.54 1.45 57.8 57.5 57.2 56.9 56.6 56.3 56.0 55.7 55.4 55.1 54.8 54.5 54.2 53.9 53.6 53.3 53.0 52.7 52.4 52.1 51.8 51.5 51.1 50.8 50.5 50.2 49.8 49.5 49.2 48.8 48.5 0.337 0.340 0.344 0.347 0.350 0.354 0.357 0.361 0.364 0.367 0.371 0.374 0.378 0.381 0.384 0.388 0.391 0.395 0.398 0.402 0.405 0.408 0.412 0.415 0.419 0.422 0.425 0.429 0.432 0.436 0.439 0.0748 0.0742 0.0736 0.0730 0.0724 0.0717 0.0711 0.0705 0.0699 0.0692 0.0686 0.0679 0.0673 0.0666 0.0659 0.0652 0.0646 0.0639 0.0632 0.0625 0.0618 0.0610 0.0603 0.0596 0.0589 0.0581 0.0574 0.0567 0.0559 0.0551 0.0544 Vapor Heat Thermal Temperature, Pressure, Viscosity, Density, Capacity, Conductivity, °F psia lb/ft·h lb/ft3 Btu/lb·°F Btu/h·ft·°F 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440 450 460 470 480 490 500 1.49 1.84 2.24 2.72 3.27 3.91 4.65 5.50 6.46 7.55 8.78 10.16 11.71 13.43 15.33 17.45 19.77 22.32 25.12 28.17 31.49 35.10 39.00 43.21 47.75 52.63 57.86 63.46 69.44 75.81 1.38 1.31 1.24 1.18 1.12 1.07 1.03 0.98 0.94 0.90 0.86 0.83 0.80 0.77 0.74 0.71 0.69 0.67 0.64 0.62 0.60 0.59 0.57 0.55 0.53 0.52 0.51 0.49 0.48 0.46 48.1 47.8 47.4 47.0 46.7 46.3 45.9 45.5 45.1 44.7 44.3 43.9 43.5 43.1 42.6 42.2 41.7 41.3 40.8 40.4 39.9 39.4 38.9 38.4 37.9 37.4 36.8 36.3 35.8 35.2 0.442 0.446 0.449 0.453 0.456 0.459 0.463 0.466 0.470 0.473 0.476 0.480 0.483 0.487 0.490 0.494 0.497 0.500 0.504 0.507 0.511 0.514 0.517 0.521 0.524 0.528 0.531 0.534 0.538 0.541 0.0536 0.0528 0.0521 0.0513 0.0505 0.0497 0.0489 0.0481 0.0473 0.0465 0.0457 0.0449 0.0441 0.0432 0.0424 0.0416 0.0407 0.0399 0.0390 0.0382 0.0373 0.0365 0.0356 0.0348 0.0339 0.0330 0.0321 0.0313 0.0304 0.0295 Physical Properties of Secondary Coolants (Brines) Table 15 Summary of Physical Properties of Polydimethylsiloxane Mixture and d-Limonene Polydimethylsiloxane Mixture d-Limonene Flash point, °F, closed cup Boiling point, °F Freezing point, °F Operational temperature range, °F Source: Dow Corning (1989). 31.13 ranges or simply on standard physical property estimation techniques. The compound (molecular formula C10H16) is derived as an extract from orange and lemon oils. The mixture of dimethylsiloxane polymers can be used with most standard construction materials; d-limonene, however, can be quite corrosive, easily autooxidizing at ambient temperatures. This fact should be understood and considered before using d-limonene in a system. 116 347 –168 –100 to 500 115 310 –142 None published REFERENCES Thermal Conductivity, Btu/h·ft·°F 0.0794 0.0764 0.0734 0.0704 0.0674 0.0644 0.0614 0.0584 0.0554 Carrier Air Conditioning Company. 1959. Basic data, Section 17M. Syracuse, NY. CCI. 1953. Calcium chloride for refrigeration brine. Manual RM-1. Calcium Chloride Institute. Dow Chemical. 1998. Syltherm XLT heat transfer fluid. Midland, MI. Dow Chemical USA. 2001a. Engineering and operating guideline for DOWFROST and DOWFROST HD inhibited propylene glycol heat transfer fluids. Midland, MI. Dow Chemical USA. 2001b. Engineering manual for DOWTHERM SR-1 and DOWTHERM 4000 inhibited ethylene glycol heat transfer fluids. Midland, MI. Dow Corning USA. 1989. Syltherm heat transfer liquids. Midland, MI. Melinder, Å. 2007. Thermo-physical properties of aqueous solutions used as secondary working fluids. Ph.D. dissertation, Department of Energy Technology, Kungliga Tekniska Högskolan, Stockholm. Available from http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4406. Table 16 Physical Properties of d-Limonene Temperature, Specific Heat, Viscosity, °F Btu/lb·°F lb/ft·h –100 –50 0 50 100 150 200 250 300 0.30 0.34 0.37 0.41 0.44 0.48 0.51 0.54 0.58 9.2 6.8 5.1 3.9 2.9 2.2 1.7 1.5 1.0 Density, lb/ft3 57.1 55.8 54.5 53.2 51.8 50.4 49.0 47.6 46.0 NONHALOCARBON, NONAQUEOUS FLUIDS Numerous additional secondary refrigerants, used primarily by the chemical processing and pharmaceutical industries, have been used rarely in the HVAC and allied industries because of their cost and relative novelty. Before choosing these types of fluids, consider electrical classifications, disposal, potential worker exposure, process containment, and other relevant issues. Tables 14 to 16 list physical properties for a mixture of dimethylsiloxane polymers of various relative molecular masses (Dow Corning 1989) and d-limonene. Information on d-limonene is limited; it is based on measurements made over small data temperature BIBLIOGRAPHY ACGIH. Annually. TLVs® and BEIs®. American Conference of Governmental Industrial Hygienists, Cincinnati. ASM. 2000. Corrosion: Understanding the basics. J.R. Davis, ed. ASM International, Materials Park, OH. Born, D.W. 1989. Inhibited glycols for corrosion and freeze protection in water-based heating and cooling systems. Midland, MI. Fontana, M.G. 1986. Corrosion engineering. McGraw-Hill, New York. NACE. 1973. Corrosion inhibitors. C.C. Nathan, ed. National Association of Corrosion Engineers, Houston. NACE. 2002. NACE corrosion engineer’s reference book, 3rd ed. R. Baboian, ed. National Association of Corrosion Engineers, Houston. ...
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This note was uploaded on 03/08/2011 for the course ASME 293 taught by Professor Range during the Spring '11 term at Prairie View A & M.

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