《制冷與低溫原理》課件B第二章 制冷與低溫工質(zhì)的性質(zhì) 2 (2.3)26

1、2 Properties of refrigeration and cryogenic working substances2.1 Introduction2.2 Properties of working substances2.3 Thermodynamic properties of pure refrigerants第二章 制冷與低溫工質(zhì)的性質(zhì)第一節(jié) 概 述第二節(jié) 工質(zhì)的性質(zhì)第三節(jié)純工質(zhì)的熱力學(xué)性質(zhì)2.3 Thermodynamic properties of pure refrigerants2.3.1 Introduction 2.3.2 Equations of state (E

2、OS)2.3.3 Phase equilibrium equations2.3.4 Calculation of thermodynamic properties第三節(jié)純工質(zhì)的熱力學(xué)性質(zhì)一、引言二、狀態(tài)方程三、相平衡方程四、熱力學(xué)性質(zhì)計算8/1/202232.3.1 Introduction一、引言：熱力學(xué)性質(zhì)Equilibrium statesHeatThermodynamicsThermodynamic PropertiesWorkEquilibriumstate8/1/20224Thermodynamic tables 熱力學(xué)表表2-6 一些制冷與低溫工質(zhì)的基本熱力性質(zhì) 工質(zhì)符號 相對分

3、子質(zhì)量 正常沸點/ 凝固點/ 臨界溫度/ 臨界壓力/kPa 臨界比體/ （L/.kg） R704 4.0026 -268.9 -267.9 228.8 14.43 R702 2.0159 -252.8 -259.2 -239.9 1315 33.21 R720 20.183 -246.1 -248.6 -228.7 3397 2.070 R728 28.013 -198.8 -210 -146.9 3396 3.179 R729 28.97 -194.3 -140.7 3772 3.048 R740 39.948 -185.9 -189.3 -122.3 4895 1.867 R732 31.

4、9988 -182.9 -218.8 -118.4 5077 2.341 R50 16.04 -161.5 -182.2 -82.5 4638 6.181 R14 88.01 -127.9 -184.9 -45.7 3741 1.598 R1150 28.05 -103.7 -169 9.3 5114 4.37 TaTTcTbTf1atm8/1/20225ssTvTThermodynamic charts熱力學(xué)圖hpTsphhpv8/1/202262.3.2 Equations of state (EOS)二、狀態(tài)方程f（p、v、T）0獨立的狀態(tài)參數(shù)數(shù)目Independentstate par

5、ametersPure substancesn + 1f（p、v、T、zi）0Mixtures 組成一定的閉系的平衡狀態(tài)，可用n1個獨立的狀態(tài)參數(shù)來限定它。n是準靜功形式的數(shù)目，1是系統(tǒng)與外界的熱交換。8/1/202272.3.2 Equations of state (EOS)二、狀態(tài)方程 Ideal gas equation of state Real gas equation of state8/1/202282.3.2.1 Cubic equations of state ( VDW EOS, 1872 )（一）立方型方程（范德瓦爾方程）VDW EOS Constrains約束斥力項引

6、力項8/1/202292.3.2.1 Cubic equations of state (RK EOS, 1872 and RKS EOS, 1972) （一）立方型方程（RK方程和RKS方程）RK EOS and RKS EOSFor RK EOSVDW EOSFor RKS EOS8/1/2022102.3.2.1 Cubic equations of state （PR EOS , 1949) （一）立方型方程（PR方程）VDW EOSPR EOSFor RKS EOSFor PR EOS8/1/2022112.3.2.2 Virial type equations of state (

7、Virial EOS, 1901) （二）維里型方程（多參數(shù)方程）OnnesVirial EOS 1Virial EOS 28/1/2022122.3.2.2 Virial type equations of state （BWR EOS, 1940) （二）維里型方程（BWR方程）BWR EOS1.8c, Max:1.75，Average: 0.358/1/2022132.3.2.2 Virial type equations of state (MH EOS, 1955, 1959, 1981) （二）維里型方程（馬丁-侯方程） MH EOSi10R0i2A2B2C2i3A3B3C3i4A

8、40/B40i50/A5B50/C5MH55 MH59 MH81（2-4） 臨界點拐點pRT/vp 0T 8/1/2022142.3.3 Phase equilibrium equations三、相平衡方程T=T （Heat balance）(Heat transfer)p=p （Force balance）(Work transfer)= （Phase balance）(Mass transfer)Tsp= f ( p,T )8/1/202215Ts2.3.4 Calculation of thermodynamic properties: a example 四、熱力學(xué)性質(zhì)計算：舉例Sin

9、gle phase regionTwo phase regionSingle phase regionSubcool liquidSaturated liquidWet vaporSaturated gasSupheat gasT、PT(P)T(P)（2-2）T(P)T、Pvv vvvx（1-x）vx v”v”vhh hhhx（1-x）hx h”h”hss sssx（1-x）sx s”s”sp8/1/2022162.3.4 Calculation of thermodynamic propertiesA example (based on MH EOS) T = 30: T = T + 273

10、.15 p = 498v = R * T / p10 pp = p1 + p2 + p3 + p4 + p5 + p6 ddp = (pp - p) / p If Abs(ddp) = 0.00001 Then GoTo 11 v = v + ddp / 100 GoTo 1011 vv = vTsp8/1/2022172.3.4 Calculation of thermodynamic properties: a example 四、熱力學(xué)性質(zhì)計算：舉例Single phase regionTwo phase regionSingle phase regionSubcool liquidSa

11、turated liquidWet vaporSaturated gasSupheat gasT、PT(P)T(P)（2-2）T(P)T、Pvv vv（2-3）vx（1-x）vx v”v”（2-1）v（2-1）hh hh（2-8）hx（1-x）hx h”h”（2-5）h（2-5）ss ss（2-9）sx（1-x）sx s”s”（2-6）s（2-6）Tsp8/1/2022182.3.4 Calculation of thermodynamic properties: a example 四、熱力學(xué)性質(zhì)計算：舉例Tsp8/1/2022192.3.4 Calculation of thermodyn

12、amic properties四、熱力學(xué)性質(zhì)計算Tsp8/1/2022202.3.4 Calculation of thermodynamic properties四、熱力學(xué)性質(zhì)計算Tsp8/1/2022212.3.4 Calculation of thermodynamic properties: a example 四、熱力學(xué)性質(zhì)計算：舉例Single phase regionTwo phase regionSingle phase regionSubcool liquidSaturated liquidWet vaporSaturated gasSupheat gasT、PT(P)T(P)（2-2）T(P)T、Pvv vv（2-3）vx（1-x）vx v”v”（2-1）v（2-1）hh hh（2-8）hx（1-x）hx h”h”（2-5）h（2-5）ss ss（2-9）sx（1-x）sx s”s”（2-6）s