# Great Sensible Heat Factor - GSHF

## The Great Sensible Heat Factor is the ratio sensible to total heat in a cooling coil.

A cooling coil should have the capacity to handle the heat load generated in the room in addition the capacity to cool down the fresh make up air. The **Great Sensible Factor** is independent of the total air flow and can be expressed as

GSHF = [Q_{s}+ m_{f}c_{p}(t_{f}- t_{r})] / [Q_{t}+ m_{f}(h_{f}- h_{r})](1)

where

GSHF= Great Sensible Heat Factor

Q_{s}= sensible heat generated in the room (kW)

m_{f}= fresh air mass flow (make up air) (kg/s)

c_{p}= specific heat of air (kg/kg.^{o}C)

t_{f}= temperature in fresh air (^{o}C)

t_{r}= temperature in room air (^{o}C)

Q_{t}= total heat generated in the room (kW)

h_{f}= specific enthalpy of fresh air (kJ/kg^{o}C)

h_{r}= specific enthalpy of air in the room (kJ/kg^{o}C)

### Example - Great Sensible Heat Factor - GSHF

The sensible heat generation in a room is *4 kW *and the latent heat generated is *1.4 kW*. The room is cooled with an air flow of *1000 kg/h*.

The fresh (out door) air temperature is *28 ^{o}C* with a specific enthalpy of

*60 kJ/kg*and a humidity ratio of

*12.7 g/kg*.

The room temperature is *22 ^{o}C* with a specific enthalpy of

*45 kJ/kg*and a specific humidity of

*9.1 g/kg*.

The Great Sensible Heat Factor can be calculated like

GSHF= [(4000 W) + (1000 kg/h)(1/3600 s/h)(1000 J/kg^{o}C)(28^{o}C - 22^{o}C)] / [(4000 W + 1400 W) + (1000 kg/h)(1/3600 s/h)(60000 J/kg - 45000 J/kg)]

= 0.59