上海交通大学：《热力学 Thermodynamics（I）》课程教学资源（课件讲义）Lecture 39-40_vapor power cycles

Engineering Thermodynamics I Lecture 39-40 Chapter 10 Vapor and Combined Power Systems Spring,2017 Prof.,Dr.Yonghua HUANG http://cc.sjtu.edu.cn/G2S/site/thermo.html 上游充通大学 Wednesday,April 26,2017 1 SHANGHAI JLAO TONG UNIVERSITY

Wednesday, April 26, 2017 1 Engineering Thermodynamics I Lecture 39-40 Spring, 2017 Prof., Dr. Yonghua HUANG Chapter 10 Vapor and Combined Power Systems http://cc.sjtu.edu.cn/G2S/site/thermo.html

Vapor Power Cycle Goal:To generate electricity from heat input Stack A-D:major subsystems Focus::heat→work -- D C Combustion gases to stack Electric Turbine generator Boiler Cooling tower Fuel W Condenser Air Warm water B Pump Cooled water Feedwater pump Makeup water 上游充通大学 Wednesday,April 26,2017 2 SHANGHAI JIAO TONG UNIVERSITY

Wednesday, April 26, 2017 2 Vapor Power Cycle Goal: To generate electricity from heat input A-D: major subsystems Focus: heatwork

Continue Vapor Power Cycle Heat Input Sources: Fossil fuels (oil,coal,natural gas) Nuclear fission/fussion ●Geothermal 。Solar radiation -->Renewable,low grade enere ·Garbage/Trash Cycle Working Fluid: ·Water/Steam Vaporization/Condensation Environmental Issues: ●Air pollution ·Thermal pollution ·Waste products ·Safety 上游通大学 Wednesday,April 26,2017 3 SHANGHAI JLAO TONG UNIVERSITY

Wednesday, April 26, 2017 3 Continue Vapor Power Cycle Heat Input Sources: • Fossil fuels (oil, coal, natural gas) • Nuclear fission/fussion • Geothermal • Solar radiation • Garbage/Trash Cycle Working Fluid: • Water/Steam Environmental Issues: • Air pollution • Thermal pollution • Waste products • Safety Vaporization/Condensation Renewable, low grade energy

Modeling Vapor Power Cycle Question:What is the upper limit of vapor power cycle performance? Answer: 1→2：adiabatic,reversible compression 2→3：isothermal,reversible heat input T 3→4：adiabatic,reversible expansion QH -TAS23 4>1:isothermal,reversible heat rejection 2。 3 Note:Whet =Qu-QL Qu=[Tds=TnASz T. 4 QL=TAS14 Q=∫Tds=TAS41 上游充通大 Wednesday,April 26,2017 4 SHANGHAI JLAO TONG UNIVERSITY

Wednesday, April 26, 2017 4 Modeling Vapor Power Cycle Question: What is the upper limit of vapor power cycle performance? Answer: 12: adiabatic, reversible compression 23: isothermal, reversible heat input 34: adiabatic, reversible expansion 41: isothermal, reversible heat rejection net H L 3 H H 23 2 1 L L 41 4 Note : W Q Q Q Tds T S Q Tds T S           1 2 3 4 s T QH = TS23 QL = TS14 Wnet TH TL

Carnot Power Cycle System Schematic: hot reservoir TH e TH constant reversible,isothermal reversible,adiabatic Wout reversible,isothermal TL=constant Q Thermal Efficiency: cold reservoir @TL nth.c =Qn-Q=1-Q=1-TASL=1-T THAS23 上降文通大学 Wednesday,April 26,2017 5 SHANGHAI JIAO TONG UNIVERSITY

Wednesday, April 26, 2017 5 Carnot Power Cycle System Schematic: hot reservoir @ TH TH = constant cold reservoir @ TL TL = constant QH  QL  Win  Wout  reversible, isothermal reversible, isothermal net H L L L 41 L th,C H H H H 23 H Thermal Efficiency : W Q Q Q T S T 1 1 1 Q Q Q T S T             reversible, adiabatic