The total amount of cooling input to the air approximates to;
H1-3 = m x (h1 - h3)
The sensible heat removed is:
H1-2 = m x (h1 - h2)
The latent heat removed is:
H2-3 = m x (h2 - h3)
where: H = Cooling energy (kW)
m = mass flow rate of air (kg/s)
h = specific enthalpy of air (kJ/kg) found from psychrometric chart.
In the absence of a suitable psychrometric chart the following formula may be used;
The sensible heat removed is: H1-2 = m x Cp x (t1 - t2)
The latent heat removed is: H2-3 = m x hfg x (g2 - g3)
where: H = Cooling energy (kW)
m = mass flow rate of air (kg/s)
Cp = Specific heat capacity of air, may be taken as 1.01 kJ/kg degC.
t = Dry bulb temperature of air (oC)
hfg = latent heat of evaporisation, may be taken as 2454 kJ/kg @20oC.
g = moisture content of air from psychrometric chart (kg/kg dry air)