The heating load is the amount of heat energy required to be added to a specific space to maintain the temperature in an acceptable range. The cooling load is the amount of heat energy required to be removed from the space to keep the temperature in an acceptable range.

Heat sources are considered to be two types, one resulting in an internal heat load on the conditional space and those resulting in an external heat load.

Those belonging to the external heat load category are a source of load on the indoor equipment, but do not affect the air it has passed through the equipment.

Heat sources which result to an internal heat like heat conduction through the glass, walls, etc. Heat sources which result in an external heat load, heat from any source added in the air after it leaves a space.

The heat load formula is given as,

Heat load = Q = m × Cp ×ΔT

Where,

m = mass flow rate,

Cp = specific heat,

ΔT = change in temperature.

Example 1

Determine the heat load in the electric convector in which the rate of mass flow is 5.45 and Cp is 1000 and the enthalpy is from 21.5 to 26.55.

Solution:

Given:

M = 4.45,

Cp = 1000,

T1 = 26.55,

T2 = 21.5

Substituting in the formula,

Heat load , Q = m ×Cp ×ΔT

= 5.45 x 1000 x (26.55 – 21.5)

= 27522.5

Example 2

Determine the heat load if the specific heat is 200 and enthalphy change from the temperature 31.5 to 26.55 and M is 4.45.

Solution:

Given:

M = 4.45,

Cp = 200,

T1 = 31.5

T2 = 26.55.

Substituting in the formula,

Heat load, Q = m × Cp ×ΔT

= 4.45 x 200 x (31.5 – 26.55)

= 4405