Question

Find the least power of a perfect reversed heat engine that makes 400 kg of ice per hour at – 8°C from feed water at 18°C. Assume specific heat of ice as 2.09 kJ/kg K and latent heat 334 kJ/kg.

Answer 1

T₁ = 18 + 273 = 291 K 

T₂ = – 8 + 273 = 265 K

Heat absorbed per kg of water (to form ice at – 8°C i.e., 265 K), R_n 

= 1 × 4.18 (291 – 273) + 334 + 1 × 2.09 × (273 – 265) = 425.96 kJ/kg