Engineering tools · Free to use
Moist Air Process Enthalpy and Water Change
Calculate the change in moist-air enthalpy flow and water-vapour flow from inlet and outlet conditions and dry-air mass flow.
Inputs
Inputs and calculations stay in this browser.
Result
Air-side enthalpy flow change: kW
Air-side water-vapour flow change: kg/s
A positive result means an increase from inlet to outlet; negative means a decrease. Water change is the net change in air-side water vapour.
Equations
ΔḢ = ṁda(hout − hin)
Δṁw = ṁda(wout − win)
Use h in kJ/kg dry air and w in kg water vapour/kg dry air. Results are kW and kg/s respectively.
Applicability
Steady state with the same dry-air mass flow at inlet and outlet; humidity ratio and enthalpy are per unit mass of dry air, and both enthalpies must use the same reference state. Neglect air kinetic-energy effects; the user must verify that inputs represent valid moist-air states.
This tool does not split enthalpy change into sensible and latent components or infer condensation from moisture removal; dehumidification may occur by different processes. Enthalpy carried by injected water, steam or drainage and heat losses may make the equipment's external heating or cooling duty differ from the air-side enthalpy change.
Worked example
For 1 kg/s dry air, inlet to outlet enthalpy 30 → 60 kJ/kg dry air and humidity ratio 8 → 12 g/kg dry air: enthalpy change is +30 kW and air-side water-vapour change is +0.004 kg/s.
For engineering estimates; verify equipment loads against complete mass and energy balances, operating conditions and applicable standards.