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Engineering ToolBox > Latent Heat Flow

Latent heat is the heat that when supplied to, or removed from air, there is a change in the moisture content of the air, but the temperature of the air is not changed

English (Imperial) units

The latent heat flow can be expressed in English (Imperial) units as:

Q_l = 60 h_we ρ q Δx (1)

where

Q_l = latent heat flow (Btu/hr)

h_we = 1060 - latent heat of vaporization of water (Btu/lb)

ρ = 0.075 - air density at standard conditions (lb/ft³)

q = measured air flow (ft³/min)

Δx = humidity ratio difference (lb water/lb dry air)

SI-Units

The latent heat flow can also be expressed in SI-units (metric) as:

Q_l = h_we ρ q Δx / 3600 (2)

where

Q_l = latent heat flow (kW)

h_we = 2,465.56 - latent heat of vaporization of water (kJ/kg)

ρ = 1.202 - air density at standard conditions (kg/m³)

q = air flow (m³/hr)

Δx = humidity ratio difference (kg water/kg dry air)

• Sensible Heat