- #1
Sirsh
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Homework Statement
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.
Homework Equations
Q(12)-W(12)=U2-U1
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.