400 kg of salmon are to be frozen from an initial temperatur

400 kg of salmon are to be frozen from an initial temperature of 12°C to a final temperature of -25°C. How much heat must be removed? (Cp above freezing = 2.981 kJ/kg°C; Cp below freezing = 1.641 kJ/kg°C; freezing temperature = -2.2°C; latent heat = 213.47 kJ/kg)

Solution

Total Heat Removed = Heat Required to brought the salmon from 12C to -2.2C + Latent heat of fusion + Heat required to change the temperature from -2.2C to -25C

=> 400kg * 2.981 kJ/kg * (14.2) + 213.47 kJ/kg * 400 kg + 400 kg * 1.641 kJ/kg * (25-2.2)

=> 16932.08 kJ + 85388 kJ + 14965.92

=> 117286 kJ