Sensible Heat Flow

Sensible Heat Flow - SI-Units

The sensible heat flow can be expressed in SI-units (metric) as

Q_s = c_p ρ q Δt / 3600                            (1)

where

Q_s = sensible heat flow (kW)

c_p = 1.005* - specific heat air (kJ/kg K)

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

q = air flow (m³/hr)

Δt = temperature (^oC)

* Note that air properties changes with temperature. Interpolate values if necessary.

Sensible Heat Flow - English (Imperial) units

In English (imperial) units the sensible flow heat can be expressed as

Q_s= 60 c_p ρ q Δt

= 1.075 q Δt                                    (2)

where

Q_s = sensible heat flow (Btu/hr)

c_p = 0.2388 - specific heat (Btu/lb^oF)

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

q = air flow in (ft³/min)

Δt = temperature difference (^oF)

• Latent heat

Example - Sensible Heat Flow

10000 m³/h of air is transported through a building with the ventilation system. The temperature of the make up air is 0 ^oC. The temperature of the room air is 20 ^oC.

The sensible heat flow can be calculated as

Q_l = (1.005 kJ/kg) (1.202 kg/m³) (10000 m³/h) ((20 ^oC) - (0 ^oC)) / 3600 

    = 67 kW