humid heat

English

Noun

humid heat (plural humid heats)

1. the heat capacity (specific heat) of humid air, expressed per unit mass of dry air in the mixture. The engineering symbol is c_s.

Usage notes

For ordinary engineering calculations in the range 0 to 50°C the following expressions are used to calculate humid heat:

In U.S. customary units, c_s = 0.24 + 0.45H where 0.24 BTU/lb°F is the heat capacity of dry air, 0.45 BTU/lb°F is the heat capacity of water vapor, and H is the specific humidity in lb water vapor per lb dry air in the mixture.

In SI units, c_s = 1.005 + 1.82H where 1.005 kJ/kg°C is the heat capacity of dry air, 1.82 kJ/kg°C the heat capacity of water vapor, and H is the specific humidity in kg water vapor per kg dry air in the mixture.

References

Perry's Handbook of Chemical Engineering, 6th edition; section 12, Psychrometry.

Çengel and Boles, Thermodynamics, an Engineering Approach, 4th edition, chapter 13, Psychrometry