Question #188974

Calculate the efficiency of an ice making machine that takes in water at 10°C and produces ice at a temperature of -7°C. Water is taken in at a rate of 1 kg every 4 minutes. The input power of the machine is 400 W.

The specific heat capacity of water is 4187 Jkg−1K−1 and its specific latent heat of fusion is 334 Jkg−1.

Expert's answer

Mass of flow rate of water = Rate of ice making(m)=\frac{1 kg}{4\times 60 sec} =4.166\times 10^{-3} kg/sec

Amount of heat absorbed (Q)= Sensible Heat +latent heat=m(Cp \Delta T+h_{fg} )

=4.166\times 10^{-3} (4187x17^o+334 )=296.48 watt

Input Power(W)=400 watt

Efficiency of cooling system =\frac{}{} \frac {Desired\: Cooling \: Effect}{Input \: Power}\times 100=\frac{296.48}{400}\times 100 =73.21 %

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