Answer to Question #86013 in Molecular Physics | Thermodynamics for Beast

Question

The air flows into the 0.5 kg / s heat exchanger at + 5 ° C and the relative humidity 20%.
How much heating power is needed and how much water must be injected into the air when
it wants to be + 30 ° C and 50%? The required power is

Answer 1

From the psychrometric chart, the enthalpy of the initial air is 5 kJ/kg. Proceeding at constant humidity to a temperature of 30 °C, the enthalpy is found to be 25 kJ/kg.

Total energy supplied in heating/reheating = 25 - 5 = 20 kJ/kg.

Energy taken in by air = 20 x 0.5 kJs-1 = 10 kW - required power.