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clear;
clc;
// A Textbook on HEAT TRANSFER by S P SUKHATME
// Chapter 9
// Mass Transfer
// Example 9.8
// Page 369
printf("Example 9.8, Page 369 \n \n");
V = 0.5 ; // [m/s]
T_h = 30 ; // [C]
T_c = 26 ; // [C]
Tm = (T_h+T_c)/2;
// From table A.2
rho = 1.173 ; // [kg/m^3]
Cp = 1005 ; // [J/kg K]
k = 0.02654 ; // [W/m K]
alpha = k/(rho*Cp); // [m^2/s]
// From Table 9.2 at 301 K
Dab = 2.5584*10^-5 ; // [m^2/s]
lambda = 2439.2*10^3 ; // [J/kg]
// Substituting in equation 9.7.5
// let difference = rho_aw-rho_a infinity
difference = rho*Cp*((alpha/Dab)^(2/3))*(T_h-T_c)/lambda;
// From steam table
Psat = 3363;
rho_aw = Psat/(8314/18*299);
rho_inf = rho_aw - difference;
x = rho_inf/rho; // mole fraction of water vapour in air stream
PP = rho_inf*8314/18*303; // Partial pressure of water vapour in air stream
// From steam table partial pressure of water vapour at 30 C
PP_30 = 4246 ; // [N/m^2]
rel_H = PP/PP_30;
percent = rel_H*100;
printf("Relative humidity = %f i.e. %f percent ",rel_H,percent);
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