《制冷与低温原理》课件C第三章 蒸气制冷循环 2 (3.1.2 - 3.1.4)21

1、3.1 One-stage vapor compression systems3.1.1 Ideal cycles using pure refrigerants3.1.2 Practical cycles using pure refrigerants3.1.2.1 Real cycles3.1.2.2 Practical cycles3.1.2.3 Simplified practical cycles第一节单级蒸气压缩制冷循环一、纯工质理论循环二、纯工质实际循环（一）真实循环（二）实际循环（三）简化的实际循环8/1/202223 Vapor refrigeration cycles第三章

2、 蒸汽制冷循环Vapor refrigeration cyclesRefrigeration cycles( Phase change )Gas refrigeration cyclesVapor compression cyclesVapor absorption cycles8/1/202233.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环 3.1.2.1 Real cycles （一）真实循环Reversible cycles (可逆)Theoretical cycles (理论)Practical cycles (实际)R

3、eversible cycles (可逆)Irreversible cycles (不可逆)Refrigeration cycles( Reversibility )8/1/202243.1.1 Ideal cycles using pure refrigerants 一、纯工质理论循环3.1.1.5 Summary （五）小结过冷循环过热循环饱和循环回热循环8/1/202253.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.2 Practical cycles （二）实际循环Temperature difference

4、不可逆因素Flowing resistance饱和循环8/1/202263.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环 3.1.2.1 Real cycles （一）真实循环Reversible cycles (可逆)Theoretical cycles (理论)Practical cycles (实际)Reversible cycles (可逆)Irreversible cycles (不可逆)Ideal cycles (理想)Practical cycles (实际)Refrigeration cycles( Reversi

5、bility )8/1/202273.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.2 Practical cycles （二）实际循环Temperature difference不可逆因素Flowing resistance8/1/202283.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环 1. Polytropic compression 多变压缩2. With

6、temperature diffidence and no pressure loss heat exchange 等压有温差换热3. Adiabatic isenthalpic proc 绝热节流8/1/202293.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环 对采用R22为制冷工质的房间空调器进行热力计算（循环质量流量qm 、冷凝负荷Qk、电功率Pel、性能系数EER和热力学完善度e）。设计参数为：制冷量3kW，室外温度35，房间温度

7、27。制冷工质与高、低温热源间的温差为20，过冷度5，过热度20。压缩机指示效率为0.7，机械效率为0.8，电动机效率为0.9，散热系数为0.6，蒸发器出口为饱和蒸汽。User specified: Q0 、TH、TLDesigner chosen: TH、TL、el 、 fDesign8/1/2022103.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环User specified: TH、TL、Q0Designer chosen: TH、

8、TL、el 、 fIndexExpressionsInfluence to cycle1pkTkTHTk pkps(Tk)TH、TLelimmof1Qf/Pel2p0T0TLT0 p0ps(T0)3t2h2（h2s- h1）f/elh1 t2t(h2 , pk )8/1/2022113.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环iw0 /wi P0 /Pii：指示效率mPi /Psm：摩擦效率moPs/Pelmo：电机效率elimmoel

9、：电效率sims：轴效率User specified: TH、TL、Q0Designer chosen: TH、TL、el 、 f8/1/2022123.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环IndexExpressionsInfluence to cycle1pkTkTHTk pkps(Tk)TH、TLelimmof1Qf/Pel2p0T0TLT0 p0ps(T0)3t2h2（h2s- h1）f/elh1 t2t(h2 , pk )

10、User specified: TH、TL、Q0Designer chosen: TH、TL、el 、 f8/1/2022133.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环1. h2（h2s- h1）f /elh1 （小型）排气温度 t2的确定：t2t (h2 , pk )PelHQf fPelH f qm (h2s- h1) /elqm(h2- h1) f1Qf/Pel2. h2（h2s- h1）/ih1 （中、大型）elimmo8/1

11、/2022143.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环IndexExpressionsDefinition4q0q0h0 - h55w0w0h2s - h1welhs - h16qmqmQ0/q0el：电效率7P0P0qmw0elimmo8PiPiP0/iqmwii：指示效率9PsPsPi/mP0/sqmwsm：摩擦效率10PelPelPs/moP0/elqmwelmo：电机效率11ssQ0/Ps0sKe（大中型）sim 轴效率12

12、EER EERQ0/Pel0elEnergy Efficiency Ratio130 0s/cEER/c热力学完善度8/1/2022153.1.2 Practical cycles using pure refrigerants 一、纯工质实际循环3.1.2.3 Simplified practical cycles （二）简化的实际循环IndexExpressionsInfluence to cycle14qkqkh2 - h4q0w0Material cost15QkQkqmqk16qvqvq0/v16qmqmQ0/q0User specified: TH、TL、Q0Designer ch

13、osen: TH、TL、el 、 f3.1 One-stage vapor compression systems3.1.1 Ideal cycles using pure refrigerants3.1.2 Practical cycles using pure refrigerants3.1.3 Cycles using mixed refrigerants 3.1.4 Analysis of cycles 第一节单级蒸气压缩制冷循环一、纯工质理论循环二、纯工质实际循环三、混合工质循环四、循环特性分析8/1/2022173.1.3 Cycles using mixed refrigeran

14、ts三、混合工质循环Azeotropic cycles共沸工质循环Non-azeotropic cycles非共沸工质循环8/1/2022183.1.3 Practical cycles using mixed refrigerants三、混合工质循环Single composition cycles单成分循环Multiple composition cycles自复叠循环、多成分循环Non-azeotropic cycles非共沸工质循环3.1 One-stage vapor compression systems3.1.1 Ideal cycles using pure refrigera

15、nts3.1.2 Practical cycles using pure refrigerants3.1.3 Cycles using mixed refrigerants 3.1.4 Analysis of cycles 第一节单级蒸气压缩制冷循环一、纯工质理论循环二、纯工质实际循环三、混合工质循环四、循环特性分析8/1/2022203.1.4 Analysis of cycles四、循环特性分析Operation type analysis操作型分析Design type analysis设计型分析Method of cycle analysis 8/1/2022213.1.4 Analy

16、sis of cycles 四、循环特性分析3.1.4.1 Design type analysis （一）设计型分析Type of cyclesKind of refrigerantsTemperature differenceCompressor efficiencyPs Compressor motorQk CondenserQ0 Evaporatorqm Compressors, valves and pipesDesignResultsUser specified: TH、TL、Q0Designer chosen: TH、TL、el 、 f8/1/2022223.1.4 Analys

17、is of cycles 四、循环特性分析3.1.4.1 Design type analysis （一）设计型分析制冷机工况：是指制冷系统的运行环境条件 (TH、TL)。Nominal working condition 性能系数 (Coefficient of performance)热力完善度(Thermodynamic perfect degree)8/1/2022233.1.4 Analysis of cycles 四、循环特性分析3.1.4.1 Design type analysis （一）设计型分析制冷机工况：是指制冷系统的运行环境条件 (TH、TL)。8/1/2022243.

18、1.4 Analysis of cycles 四、循环特性分析3.1.4.1 Design type analysis （一）设计型分析制冷机工况：是指制冷系统的运行环境条件 (TH、TL)。Nominal working condition 性能系数 (Coefficient of performance)热力完善度(Thermodynamic perfect degree)8/1/2022253.1.4 Analysis of cycles 四、循环特性分析3.1.4.2 Operation type analysis （二）操作型分析Operation type analysisDesi

19、gn type analysisMethod of cycle analysis User specified: TH、TL、Q0Designer chosen: TH、TL、el 、 f8/1/2022263.1.4 Analysis of cycles 四、循环特性分析3.1.4.2 Operation type analysis （二）操作型分析TL= const, TH increases q0 Q0qmq0 ; v1=const, f(PR) qmqvs/v1qvt/v1 ; ws Psqmws sq0/ws ;s/c? 8/1/2022273.1.4 Analysis of cycles 四、循环特性分析3.1.4.2 Operation type analysis （二）操作型分析TH = const, TL decreases q0 Q0qmq0 ; v1, qmqvs/v1qvt/v1 ; ws Psqmws ? sq0/ws ;s/c? 8/1/2022283.1.4 Analysis of cycles 四、循环特性分析3.1.4.2 Operation type analysis （二）操作型分析TH = const, TL increasesPsPs=max8/1/2022293.1.4 Analysis of cycles 四、循环特性分析3