1. The problem statement, all variables and given/known data In a rigid sealed tank, 0.32kg of saturated H2O vapour is cooled from 16 bar to 2.70 bar. Determine the heat removed in Kj. 2. Relevant equations Q(12)-W(12)=U2-U1 3. The attempt at a solution Assuming that we're only looking at the saturated vapour internal energies, and there is no work occurring in the system. State 1 is at 16 bar, and State 2 is at 2.70 bar. ug1 = 2596 kJ/kg, ug2 = 2540 kJ/kg. Ug1 = 0.32*2596 = 830.72kJ Ug2 = 0.32*2540 = 812.80kJ Therefore, Q12 = U2 - U1 = 812.80 - 830.72 = -17.92 kJ. But this is counter intuitive as when things are compressed they general go hotter. Is my logic on this correct or am I totally in the wrong ball park? Thanks for all your help.