Heatengine

Heatengine - Ch 20. The Second Law of Thermodynamics Liu...

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Liu UCD Phy9B 07 1 Ch 20. The Second Law of Thermodynamics
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Liu UCD Phy9B 07 2 20-1. Directions of Thermodynamic Processes Reversible vs. Irreversible processes Equilibrium vs. non-equilibrium processes Converting heat into mechanical energy: how efficient? Please read text on your own .
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Liu UCD Phy9B 07 3 20-2. Heat Engine Thermal Efficiency (x100%) e = W/Q H =(| Q H |-|Q C |)/ Q H =1- | Q C /Q H | e <1 Converts heat partly into work or mechanical energy Goes through a cyclic process, thus U=0 W=Q = Q H + Q C =| Q H |-| Q C | For the heat engine Q H +; Q C -
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Liu UCD Phy9B 07 4 20-3. Internal Combustion Engines Minimum volume V Maximum volume rV Compression ratio r (typically 8-10)
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Liu UCD Phy9B 07 5 Otto Cycle Q H =nC V (T c -T b ) >0 Q C =nC V (T a -T d ) <0 b c d a b c H C H T T T T T T Q Q Q e + = + = 1 1 1 = γ r e Two adiabatic + two isochoric processes Read about Diesel cycle on your own.
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Liu UCD Phy9B 07 6 20-4. Refrigerators Here: W< 0 ; Q H <0; Q C >0 Coefficient of performance | | | | | | | | | | C H C C Q Q Q W Q K = =
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Heatengine - Ch 20. The Second Law of Thermodynamics Liu...

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