Heating Capacity of Steam Radiators and Convectors

Steam radiators and steam convectors - heat capacities and temperature coefficients

Steam Heated Radiator

The heat capacity of a steam radiator can be expressed as

H_r = q_s h_s λ_r         (1)

where

H_r = heat capacity of radiator (kW, Btu/h)

q_s = condensate rate (kg/h, lb/h)

h_s = latent heat steam (2675 kJ/kg, 970 Btu/lb)

λ_r = radiator temperature correction coefficient = 1 for room temperature 70^oF (21^oC) and steam temperature 215^oF (100^oC).

The radiator correction coefficient for other room and steam temperatures can be calculated

λ_r = [(215 - 70)/(t_s - t_r)]^1.3         (1b)

where

t_s = steam temperature (^oF)

t_r = room temperature (^oF)

Steam Heated Convector

The heat capacity of a steam heated convector can be expressed as

H_c = q_s h_s λ_c         (2)

where

H_c = heat capacity of convector (kW, Btu/h)

q_s = condensate rate (kg/h, lb/h)

h_s = latent heat steam (2675 kJ/kg, 970 Btu/lb)

λ_c = convector temperature correction coefficient = 1 for inlet temperature 65^oF (18^oC) and steam temperature 215^oF (100^oC).

The convector correction coefficient for other room and steam temperatures can be calculated

λ = [(215 - 65)/(t_s - t_i)]^1.5         (2)

where

t_s = steam temperature (^oF)

t_i = inlet temperature (^oF)

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