1. The Advanced Chemical Engineering Thermodynamics The second law of thermodynamics Q&A_-5- 10/13/2005(5) Ji-Sheng Chang

2. Heat and work  The heat and work in first law of thermodynamics  The heat and work in second law of thermodynamics The quality of the heat and work

3. Statements of second law  The second law of thermodynamics by written language statements No apparatus can operate in such a way that its only effect is to convert heat absorbed by a system completely into work done by the system No process is possible which consists solely in the transfer of the heat from one temperature level to a higher one

4. Statements of second law  The second law of thermodynamics by written language statements It is impossible by cyclic process to convert the heat absorbed by a system completely into work done by the system

5. Machines  The heat engines and refrigerator  Heat engine Using the heat to generate the work  Refrigerator Using the work to transfer the heat from a lower temperature space to a higher temperature space

6. Cyclic process  A cyclic process – heat engine Pumping water to boiler Heating water in boiler Drafting the work from water by turbine Cooling water that has exhaust from the turbine  The working fluids water

7. Heat engine  The efficiency of the heat engine THTH QHQH QCQC W TCTC

8. Reversible process  The work of expansion Case 1, P E = 0 Case 2, P E = P Eatm = 1.0 bar Case 3, P E = P P PEPE

9. Reversible process  The work of expansion P V V 1 V 2 P PEPE P PEPE V1V1 V2V2

10. Carnot’s engine  The Carnot cycle Reversible adiabatic process  Th to Tc, input work Reversible isothermal process  Adsorbed heat at Th Reversible adiabatic process  Tc to Th, output work Reversible isothermal process  Release heat at Tc Th, Qh Tc, Qc WW

11. Carnot’s theorem  The efficiency of the Carnot ’ s engine For two given heat reservoirs no engine can have a thermal efficiency higher than that of a Carnot engine An Engine /Refrigerator combination

12. Carnot’s theorem  The Carnot’s theorem If engine E has the greater of η then  The sole result of the operation is transfer of heat from temperature Tc to the higher temperature Th  This is in violation of the statement 2 of the second law

13. Temperature  What ’ s the temperature? The zeroth law of thermodynamics  The temperature scales The Celsius temperature scales The ideal gas temperature scales The thermodynamic temperature scales

14. Thermodynamic temperature scales  Deriving

15. Cyclic process  The Carnot ’ s engine  Carnot ’ s equation ； ideal-gas temperature scales Adiabatic compression Isothermal expansion Adiabatic expansion Isothermal compression

16. Definition  The definition of the entropy A states function properties

17. Entropy  The second law of thermodynamics by mathematical statements. ΔS total ≧ 0

18. Entropy  The third law of thermodynamics. The absolute entropy  Calculated the absolute entropy from classical thermodynamics ; properties as Heat capacity Heat of phase changes