Document 0JmD5Keg1M5moZjy4qRMKJqwx

64 CHAPTER 3 1956 Guide: Absolute Temperature . Gravity Density 518.67 FAbs 32.1740 ft per (sec) (sec). 0,076505 lb per cu ft Values of pressure and temperature are listed in Table 6 for altitudes in. the standard atmosphere from --1000 to 50,000 ft above sea level: For further explanation, References 9 and 10 should be consulted. LETTER SYMBOLS USED IN CHAPTER 3 p -- degree of saturation (decimal). p = density of fluid, pounds per cubic foot. <p -- relative humidity (decimal). a ratio of apparent molecular weight of dry air (28.966) to the molecular weight of water (18.016) =* 1.6078. A coefficient from Table 5 for use in Equation 30 (obtained from Table 5). B = coefficient to be used in Equation 31 (obtained from Table 5). C = coefficient for use in Equation 32 (obtained from Table 5). /, = factor accounting for effect of mixing air and water, dimensionless,....... G =* flow rate of dry air,; pounds per hour. Gi flow rate of dry air, pounds per minute. Gw = rate of evaporation of water, pounds per minute. H = enthalpy of the system. H = enthalpy of the flowing medium, Btu per pound of dry air. h = enthalpy, of moist air, Btu per pound of dry air. A = enthalpy correction term to be added above 150 F, to enthalpy. Am *= specific enthalpy of dry air, Btu per pound. hn h, -- hi the difference between the enthalpy of moist air at saturation per pound of dry air, and the specific enthalpy of the dry air itself, Btu per pound of dry air. A* enthalpy of saturated water vapor, Btu per pound. A enthalpy of moist air at saturation per pound of dry air, Btu per pound of dry air. hi* enthalpy of moistair at saturation at thermodynamic w?t-bvJb temperature, t* Btu per pound of diy air;' v ikw = specific enthalpy of condensed water (liquid or solid) at standard.pressure, Btu per pound water* . ;; Aw* a specific enthalpy of water-as added at the thermodynamic wet-buib tem perature t*, Btu per pound of dry air. . Awi " enthalpy of liquid water, Btu per pound. Awa s enthalpy of solid water,. Btu per pound. 1KE = average kinetic energy, Btu per pound, a average kinetic energy, Btu per pound. - L flow rate of liquid water, pounds per hour. m a weight of dry air crossing any duct section, pounds per minute.. n a mols dry air. n. a mols of Water vapor at saturation, nw a mols of water vapor. P absolute pressure. . -/ Pi a atmospheric pressure, inches Hg. Thermodynamics 65 LETTER SYMBOLS (Continued) p a standard atmospheric pressure by definition 29.921 in. Hg. p, a saturation pressure of pure water at prevailing temperature: p => total pressure of a mixture of air and water vapor, pounds per square inch or Hg. p, partial pressure of dry air, pounds per square inch or inches Hg. p, = saturation pressure of pure water vapor, pounds per square inch or inches Hg. p^ a partial pressure of water vapor in mixture of air and water vapor, pounds per square inch or inches Hg. PE = potential energy, Btu per pound dry air. PE average potential energy, Btu per pound dry air. Q 63 total heat added or subtracted, between sections, Btu per minute. q = ratio of energy added (or removed) to water added (or removed), Btu per pound. Also called specific enthalpy of water added. ,q, a energy added between points 1 and 2. ,qt *3 heat added between sections 1 and 2, Btuper pound dry air. A a universal gas constant, 1545 foot-pounds per (Fahrenheit degree) (mol), a gas constant for dry air. Rw = gas constant for water vapor. S = flow rate of solid water, pounds per hour. s = entropy of moist air per pound of dry air, Btu per (pound). (Fahrenheit degree). g = correction to be added to entropy of moist air obtained from Table 2. a additional correction to be added to entropy because of"mixing entropy" (obtained from Table 5). Correction to be added to value of s obtained from Table 2. v. Si = specific entropy of dry air, Btu per (pound) (Fahrenheit degree; absolute). Sim the difference between the/entropy of moist air a< saturation per pound of dry air, and the speciflo entropy of. the dry air itself, Btu per (pound of dry air) (Fahrenheit degree, absolute).. Si s entropy of moist air at saturation per pound of dry air, Btu per (pound of dry air) (Fahrenheit degree, absolute). sw = specific entropy of condensed wateror sblid). at standard atmos pheric pressure, Btu per (pound of water), (Fahi-enbeit degree, absolute). T = absolute temperature, Fahrenheit degrees. . To = standard atmospheric temperature, by definition 518.4 F absolute. t = temperature, Fahrenheit degrees. t* a thermodynamic wet-bulb temperature, Fahrenheit degrees. U = internal energy of system. U = internal energy. V -- volume. F average velocity, feet per minute. v = volume of moist air per pound of dry air, cubic feet per pound. 0 *= correction to be added to volume of moist air per pound of dry air, above 150 F. ; Vi specific volume of dry air, cubic feet per pound.