# 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

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/m^{3})

q = air flow (m^{3}/hr)

Δt = temperature (^{o}C)

* 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^{o}F)

ρ = 0.075 - air density at standard conditions (lb/ft^{3})

q = air flow in (ft^{3}/min)

Δt = temperature difference (^{o}F)

### Example - Sensible Heat Flow

*10000 m ^{3}/h* of air is transported through a building with the ventilation system. The temperature of the make up air is

*0*. The temperature of the room air is

^{o}C*20*.

^{o}CThe sensible heat flow can be calculated as

*Q _{l} = (1.005 kJ/kg) (1.202 kg/m^{3}) (10000 m^{3}/h) ((20 ^{o}C) - (0 ^{o}C)) / 3600 *

* = 67 kW*

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