Question

The following data pertain to an air-conditioning system : 

Unconditioned space DBT = 30ºC 

Unconditioned space WBT = 22ºC 

Cold air duct supply surface temperature = 14ºC. 

Determine : (i) Dew point temperature. 

(ii) Whether or not condensation will form on the duct.

Answer 1

(i) To determine the dew point temperature for the given conditions, find the intersection of 30ºC DBT and 22ºC WBT and move horizontally (as shown by the arrow) to the dew point temperature scale. The dew point (t_dp) is 18.6ºC.

(ii) Since the duct temperature (14ºC) is less than t_dp (18.6ºC) therefore moisture will condense on the duct surface.