上游充通大￥ SHANGHAI JIAO TONG UNIVERSITY Engineering Thermodynamics I Lecture 13 Spring,3/19/2019 Prof.,Dr.Yonghua HUANG 强 MALLAAMMI http://cc.sjtu.edu.cn/G2S/site/thermo.html 1日G
Engineering Thermodynamics I Lecture 13 Spring, 3/19/2019 Prof., Dr. Yonghua HUANG http://cc.sjtu.edu.cn/G2S/site/thermo.html
The relationship among p,v,T of gases? Customary T uoden leeyJedns Solid Liquid pIbrT-P!oS Critical pqint Constant- P>Pat Vapor pressure line Per Critical point P<Pex Phase Vapor change Liquid Solid-vapor Specific volume Temperature Ver 上降文通大学 March 19,2019 2 SHANGHAI JIAO TONG UNIVERSITY
March 19, 2019 2 The relationship among p, v, T of gases? superheat vapor Customary liquid
Retrieving thermodynamic properties TABLE A-6 Superheated water T 小 S Tables ℃ m3/kg kJ/kg kJ/kg kJ/kg-K P-0.01MPa(45.81℃) Sat. 14.670 2437.22583.9 8.1488 50 14.867 2443.32592.0 8.1741 100 17.196 2515.5 2687.5 8.4489 150 19.513 2587.92783.0 8.6893 200 21.826 2661.42879.6 8.9049 250 24.136 2736.1 2977.5 9.1015 300 26.446 2812.3 3076.7 9.2827 400 31.063 2969.33280.0 9.6094 Graphs 500 35.680 3132.93489.7 9.8998 600 40.296 3303.33706.3 10.1631 700 44.911 3480.83929.9 10,4056 How? 800 49.527 3665.44160.610.6312 Is it possible to have some simple relations among the properties that are sufficiently general and accurate? Equations RT a pV=RT of State 元-bD2 Computer software (EES,lT,Refprop.…) they are based on EoS 上游充通大 March 19,2019 3 SHANGHAI JIAO TONG UNIVERSITY
March 19, 2019 3 Retrieving thermodynamic properties How? Tables Graphs Equations of State … Computer software (EES, IT, Refprop…) they are based on EoS pv RT Is it possible to have some simple relations among the properties that are sufficiently general and accurate?
Ideal Gas Model ldeal gas as a collection of perfectly hard amssald Liquid spheres. Solid Critical all collisions between atoms or point p<<pc molecules are perfectly elastic and in which there are no inter- Triple point; T>Te molecular attractive forces. Temperature infinitesimally small,taking up no volume themselves (point masses) Ideal gas equation of state iPU RT pV=mRT pu=RT pV=nRT 上降文通大学 March 19,2019 4 SHANGHAI JIAO TONG UNIVERSITY
March 19, 2019 4 Ideal Gas Model Ideal gas equation of state c p p T T c • as a collection of perfectly hard spheres. • all collisions between atoms or molecules are perfectly elastic and in which there are no intermolecular attractive forces. • infinitesimally small, taking up no volume themselves (point masses) Ideal gas
Universal Gas Constant Measured data extrapolated to T 1 吧 zero pressure Volume per mole T 四 U=MU molecular T weight R卡 V2 T3 T P p lim R R R= (kJ/kg-K) p→0 T M for all gases Universal gas constant =8.314kJ/kmol·K 上泽通大学 March 19,2019 5 SHANGHAI JIAO TONG UNIVERSITY
March 19, 2019 5 Universal Gas Constant p1 , v1 p2 , v2 p3 , v3 T T T for all gases Universal gas constant Volume per mole R R M (kJ/kg·K) molecular weight