s15.2 heat engines and the second law of thermodynamics Define the efficiency of the heat engine QH H TThe first law of thermodynamics W(=Q1 does not forbid E=1 C E=1 eH 2H Perfect engine s15.2 heat engines and the second law of thermodynamics 3. The second law of thermodynamics A perfect heat engines(8=1)do not exist. 4. The examples for efficiency of heat engines a) Clausius-Rankine cycle 1→)2dp=0 QH=nC,t2-l) do=0 2→)3d0=0 12P2=73p 66 Define the efficiency of the heat engine: QH W ε = Q C The first law of thermodynamics does not forbid ε =1 Perfect engine ε =1 H C H H C Q Q Q Q Q = − − ε = 1 §15.2 heat engines and the second law of thermodynamics 3. The second law of thermodynamics A perfect heat engines (ε =1) do not exist. 4. The examples for efficiency of heat engines (a) Clausius-Rankine cycle 1 → 2 d p = 0 ( ) QH = nCp T2 −T1 2→3 dQ = 0 1 3 1 1 2 2 − − − − = γ γ γ γ T p T p §15.2 heat engines and the second law of thermodynamics