上岸充通大学 SHANGHAI JIAO TONG UNIVERSITY Engineering Thermodynamics I Lectures 3-4 Spring,2018 Prof.,Dr.Yonghua HUANG 强 A是 http://cc.sjtu.edu.cn/G2S/site/thermo.html AN 1日G
Engineering Thermodynamics I Lectures 3-4 Spring, 2018 Prof., Dr. Yonghua HUANG http://cc.sjtu.edu.cn/G2S/site/thermo.html
Chapter 1 Concepts,Systems Units ④Objective fundamental concepts:including closed system,control volume,boundary and surroundings,property,state, process,the distinction between extensive and intensive properties,and equilibrium. o apply SI Engineering units. Kelvin,Rankine,Celsius,and Fahrenheit temperature scales. apply the problem-solving methodology. 上游充通大学 March 3,2018 2 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 2 Chapter 1 Concepts, Systems & Units Objective • fundamental concepts: including closed system, control volume, boundary and surroundings, property, state, process, the distinction between extensive and intensive properties, and equilibrium. • apply SI Engineering units. • Kelvin, Rankine, Celsius, and Fahrenheit temperature scales. • apply the problem-solving methodology
1.1 System and Surroundings Thermodynamic system -Any three-dimensional region of space bounded by one or more arbitrary geometric surfaces SURROUNDINGS Surroundings SYSTEM -The region of space outside the arbitrary boundaries BOUNDARY Abstraction of system Air Air actuating shaft gasoline gasoline Automobile engine actuating shaft Boundary > exhaust gas (a) (h) 上游充通大学 March 3,2018 3 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 3 1.1 System and Surroundings Thermodynamic system –Any three-dimensional region of space bounded by one or more arbitrary geometric surfaces Surroundings –The region of space outside the arbitrary boundaries Abstraction of system Automobile engine
Boundary Imaginary boundary System boundary may be real or it could be imaginary The system may be stationary or moving rigid stationary boundary chimney Gas air imaginary boundary exhausted rigid moving boundary gas imaginary boundary diffuser compressor burner gas turbine nozzle 上游充通大学 March 3,2018 4 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 4 Boundary System boundary may be real or it could be imaginary The system may be stationary or moving Imaginary boundary chimney
Types of Systems System interaction with its surroundings: Mass No Closed ·mass/energy system Closed System m=constant allows transfer of energy only across its boundaries; Energy Yes no mass transfer Chemical composition within the system may change;but mass remains constant (volume may change) boundary Closed System Control Mass [CM] mass YES Open System Open allows both transfer of energy and mass system Open system=Control volume [CV] energyYES Simple compressible system:consists of compressible fluids,only volume change work (reversible)exchanged 上游充通大 March 3,2018 5 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 5 Types of Systems System interaction with its surroundings: • mass /energy Closed System allows transfer of energy only across its boundaries; no mass transfer • Chemical composition within the system may change; but mass remains constant (volume may change) • Closed System = Control Mass [CM] Open System allows both transfer of energy and mass • Open system= Control volume [CV] Simple compressible system: consists of compressible fluids, only volume change work (reversible) exchanged Open system
Adiabatic system,Isolated system heat insulation material Q=0 adiabatic system Adiabatic system:No heat exchange Isolated system:No energy and mass exchange 上游气通大粤 March 3,2018 6 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 6 Adiabatic system: No heat exchange Isolated system: No energy and mass exchange Adiabatic system, Isolated system
Examples for understanding system (1).Rigid adiabatic cylinder-piston system.Electrical heater in room B Red line closed,adiabatic system Yellow line without heater -closed system Yellow line with heater A B 庋 -closed,adiabatic system Blue line isolated system 上游充通大 March 3,2018 7 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 7 (1)．Rigid adiabatic cylinder-piston system. Electrical heater in room B Red line ——closed, adiabatic system Yellow line without heater ——closed system Yellow line with heater ——closed, adiabatic system Blue line ——isolated system Examples for understanding system
(2).Water heater at steady state boundarv mout outlet hot water water heater nlet min II 10L cold water mout=mn？ Close system or open system? 上游充通大 March 3,2018 8 SHANGHAI JIAO TONG UNIVERSITY
March 3, 2018 8 mout mout = min ? min Close system or open system? (2)．Water heater at steady state
(3).Chemical reaction:Calcium carbonate System? CaCO3 上游充通大学 March 3,2018 9 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 9 System? (3)．Chemical reaction: Calcium carbonate
(4).Rigid adiabatic nozzle P P. m2-r i 1 P2Cf c-velocity i-mass flow rate Red line system(gas)-Closed system Nozzle as system- Open,adiabatic system 上游充通大 March 3,2018 10 SHANGHAI JLAO TONG UNIVERSITY
March 3, 2018 10 Closed system (4)．Rigid adiabatic nozzle Red line system (gas) — Nozzle as system— Open, adiabatic system c – velocity m –mass flow rate