Question

A piston/cylinder with constant loading of piston contains 1 L water at 400 kPa, quality 15%. It has some stops mounted so the maximum possible volume is 11 L. A reversible heat pump extracting heat from the ambient at 300 K, 100 kPa heats the water to 300°C. Find the total work and heat transfer for the water and the work input to the heat pump. 

Answer 1

Take CV around the water and check possible P-V combinations.

v₁ = 0.001084 + 0.15×0.46138 = 0.07029 m³/kg

u₁ = 604.29 + 0.15 × 1949.26 = 896.68 kJ/kg

s₁ = 1.7766 + 0.15 × 5.1193 = 2.5445 kJ/kg K

m₁ = V₁/v₁ = 0.001/0.07029 = 0.0142 kg