Constants and Values Used for the Calculation of Psychrometric Properties of Moist Air Quantity Symbol Value Reference Universal molar gas constant [bar.R] 8.314472 Mohr and kJ/(kmol*K) Taylor (2005) Molar mass of dry air [M.sub.a] 28.966 Gatley et kg/kmol al.
The values for the universal molar gas constant ([bar.R]), the molar mass of dry air ([M.sub.a]), and the molar mass of water ([M.sub.w]) used for the calculation of the psychrometric properties in this section are given in Table 5.
The saturation pressure of water [p.sub.w,s] = [p.sub.s.sup.97](T) is obtained using Equation 6, and [[bar.r].sup.97] is the molar gas constant of IAPWS-IF97, given in Table 3.
where [bar.R] is the universal molar gas constant given in Table 5, and [B.sub.m] and [C.sub.m] are the second and third molar virial coefficients of the mixture given by Equations 10 and 11.
where [[psi].sub.w] is the mole fraction of water vapor, [[bar.h].sub.a.sup.o] is the ideal-gas molar enthalpy of dry air and [[bar.h].sub.w.sup.o] is the ideal-gas molar enthalpy of water vapor--both described below, [bar.v] is the molar volume of the mixture moist air calculated iteratively using Equation 47, [B.sub.m] and [C.sub.m] are calculated using Equations 10 and 11, d[B.sub.m]/dT and d[C.sub.m]/dT are calculated using Equations 12 and 13, and [bar.R] is the universal molar gas constant given in Table 5.