Sensible Heat Flow
Sensible heat is dry heat causing change in temperature but not in moisture content
Sensible Heat Flow - SI-Units
The sensible heat flow can be expressed in SI-units (metric) as
Qs = cp ρ q Δt / 3600 (1)
where
Qs = sensible heat flow (kW)
cp = 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
Qs= 60 cp ρ q Δt = 1.075 q Δt (2)
where
Qs = sensible heat flow (Btu/hr)
cp = 0.2388 - specific heat (Btu/lboF)
ρ = 0.075 - air density at standard conditions (lb/ft3)
q = air flow in (ft3/min)
Δt = temperature difference (oF)
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
Ql = (1.005 kJ/kg) (1.202 kg/m3) (10000 m3/h) ((20 oC) - (0 oC)) / 3600
= 67 kW
