A refrigerator freezes 5 kg of water at 0^(@)C into ice at 0^(@)C in 20 minutes. If the room temp. is 20^(@)C, what minimum power is needed to accomplish this ? Given latent heat of ice =336xx10^(3)J//kg.

A refrigerator freezes 5 kg of water at 0^(@)C into ice at 0^(@)C in 2

1.	A refrigerator freezes 5 kg of water at 0^(@)C into ice at 0^(@)C in 20 minutes. If the room temp. is 20^(@)C, what minimum power is needed to accomplish this ? Given latent heat of ice =336xx10^(3)J//kg.
Answer» Solution :Amount of heat required to be taken out `Q_(2)= 5xx336xx10^(3)J` , `T_(2)= 0^(@)C = (0+273)K=273K` `T_(1)= 20^(@)C= (20+273)K= 293K` COEFF. Of performance of refrigerator `Q_(2)/W= (T_(2))/(T_(1)-T_(2))=(273)/(293-273)` `:. W=(Q_(2)xx20)/(273)=(5xx336xx10^(3)xx20)/(273)` Minimum power needed , `P=W/t=(5xx336xx10^(3)xx20)/(273xx20xx60)= 102.5 "WATT"`