上游充通大学 SHANGHAI JIAO TONG UNIVERSITY Engineering Thermodynamics I Lecture 23-24 Chapter 6 The second law of Thermodynamics (Section6.1-6.3,6.6) Spring,4/8/2018 强 Prof.,Dr.Yonghua HUANG A http://cc.sjtu.edu.cn/G2S/site/thermo.html 1日
Engineering Thermodynamics I Lecture 23-24 Spring, 4/8/2018 Prof., Dr. Yonghua HUANG Chapter 6 The second law of Thermodynamics (Section 6.1- 6.3, 6.6) http://cc.sjtu.edu.cn/G2S/site/thermo.html
Why need the second law? First law-energy conservation (Quantity) dt How about the Quality of the energy? 中同人长第 4C61676666 C61676656 100 100 好好学习 上游究通大学 April 8,2018 2 SHANGHAI JIAO TONG UNIVERSITY
April 8, 2018 2 Why need the second law? First law – energy conservation How about the Quality of the energy? (Quantity)
Quality of energy 1 kJ electricity power <-1kJ heat 1 kJ chemical energy <-1kJ heat 300 上游充通大学 April 8,2018 3 SHANGHAI JLAO TONG UNIVERSITY
April 8, 2018 3 Quality of energy 1 kJ electricity power <-> 1kJ heat 1 kJ chemical energy <-> 1kJ heat
Spontaneous processes Atmospheric air at To Body at Time Time To<T<T T,>T0 Valve7 Air at Air Pi>Po Air at po<p<pi Po Mass Z< Mass 上游充通大学 April 8,2018 4 SHANGHAI JIAO TONG UNIVERSITY
April 8, 2018 4 Spontaneous processes
The inverse process Heat Tl,raising Heat Not violate the 1st law!! Iwm-9 TT,current output 上游充通大 April 8,2018 5 SHANGHAI JIAO TONG UNIVERSITY
April 8, 2018 5 The inverse process Q Q' ? Not violate the 1st law!! T↓, raising ? T↑, current output ?