Question

Water at a temperature of 15°C produces ice cubes at a temperature of −5°C. Water is taken in at the
rate of 1 kg every 7 minutes and the input power to the machine is 300 W. The specific heat capacity of
water is 4187 Jkg−1K

−1, the specific heat capacity of ice is 2100 Jkg−1K

−1 and the specific latent heat of

fusion is 335 Jkg−1
i) Calculate the heat energy extracted per kg of ice produced
ii) Calculate the thermal efficiency of the ice making machine.