Great Sensible Heat Factor - GSHF

The Great Sensible Heat Factor is the ratio between the sensible and total heat for a cooling coil

The cooling coil must have the capacity to handle the heat load in the room in addition 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 capacity of air (kg/kg.^oC)

t_f = temperature in fresh air (^oC)

t_r = temperature in room air (^oC)

Q_t = total heat generated in the room (kW)

h_f = specific enthalpy of fresh air (kJ/kg.^oC)

h_r = specific enthalpy of air in the room (kJ/kg.^oC)

Example - Great Sensible Heat Factor - GSHF

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

The fresh air (out door) temperature is 28^oC, the specific enthalpy is 60 kJ/kg and the specific humidity is 12.7 g/kg.

The room temperature is 22^oC, the specific enthalpy is 45 kJ/kg and the specific humidity is 9.1 g/kg.

The Great Sensible Heat Factor can be calculated as:

GSHF = [(4,000 W) + (1,000 kg/h)(1/3,600 s/h)(1,000 J/kg.^oC)(28^oC - 22^oC)] / [(4,000 W + 1,400 W) + (1,000 kg/h)(1/3,600 s/h)(60,000 J/kg - 45,000 J/kg)]

= 0.59

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