a condensor used in a refrigeration system has a capacity of

a condensor used in a refrigeration system has a capacity of 10 tons at 40F evaporating temp. when 20 gpm of cooling water enters at 75F, the condensing temp is 90F The manufacturer claims a U-factor of 95 Btu/h*F*ft^2 with a heat transfer area of 83 ft^2. Are these claims reasonable? Why?

Solution

The capacity of the refrigeration system is 10 Ton = 119424.97 BTU/hr

Mass of the cooling water emters is 20 gpm = 160.42 ft3/hr

Ther entering water temperature is 75F and condensing temp = 90 F

Now u factor = 1/Resistivity = 95 BTU/h*F*ft2

Thermal resistivity = material thickness/thermal conductivity co efficient.=1/95=0.01052

Now Q = U*A*(Tcond-Tenters)

=95*83*15 = 118275BTU/h

As we can see that refrigeration system capasity is greater than heat transfer rate,that is why the claims is reasonable.