Answer to Question #83815 in Mechanical Engineering for GOPAL JHA

Question

A mixture of air and water vapour at 1.013 bar and 16 degree C has a dew
point of 5degree C. Calculate the relative and specific humidity’s?

Answer 1

The saturaion pressures at the given temperatures are

$$P_s(5^o C)=872.6 Pa,\\ P_s(16^o C)=1818.8 Pa,$$

The relative humudity is given by

$$\phi=\frac{P_s(5^o C)}{P_s(16^o C)}\\ \phi= \frac{872.6}{1818.8}=0.480$$

The specific humidity is given by

$$x=\frac{P_s(5^o C)}{P-P_s(5^o C)}\\ x= \frac{872.6}{1.013\times10^5-872.6}=0.0054 kg/kg.$$