The humidity ratio (W) in lb water per lb dry air (or g/kg) is a function of which pair in typical HVAC calculations at known pressure?
Choices
- (A) Dew point only, never RH
- (B) Dry-bulb only
- (C) Relative humidity and dry-bulb (at fixed P) — with steam tables/relations for P_ws
- (D) Enthalpy only with no T
Correct answer: (C)
Relative humidity and dry-bulb (at fixed P) — with steam tables/relations for P_ws
Explanation
W from p_w = φ·p_ws(T_db) at total pressure P. ASHRAE Fundamentals equations.