1、3.2 Two-stage vapor compression systems3.2.1 Introduction3.2.2 Design type analysis3.2.2.1 Single-throttle cycles 3.2.2.2 Double-throttle cycles 3.2.3 Operation type analysis第二节第二节 两级蒸气压缩制冷循环两级蒸气压缩制冷循环一、绪论二、设计型分析（一）一次节流循环（二）二次节流循环三、操作型分析2/28/202323.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.1 Wit
2、h incomplete interstage cooling 中间不完全冷却 1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg Single-throttle cycles Double-throttle cycles 1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg 2/28/202333.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.1 With incomplete interstage cooling 中间不完全冷却Double-throttle cycles 1 2 6 7 9 4 5 10 3 qm
3、gqmd qmd qmg 2/28/202343.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.1 With incomplete interstage cooling 中间不完全冷却 1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg 1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg 1098t4tm;Qm0。2/28/202353.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.2 With complete interstage cooling 中间完全冷却Sing
4、le-throttle cycles Double-throttle cycles 2 1 6 7 9 4 5 10 3 qmd qmd qmg qmg 2 1 6 7 9 4 5 10 3 qmd qmd qmg 2/28/202363.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.2 With complete interstage cooling 中间完全冷却Double-throttle cycles 2 1 6 7 9 4 5 10 3 qmd qmd qmg 2/28/202373.2.2.2 Double-throttle cycle
5、s（二）二次节流循环 3.2.2.2.2 With complete interstage cooling 中间完全冷却t4tmQm0 1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg 2 1 6 7 9 4 5 10 3 qmd qmd qmg 2/28/202383.2.2 Design type analysis 二、设计型分析 3.2.2.2 Double-throttle cycles（二）二次节流循环User specified:TH、TL、Q0Designer chosen:TH、TL、Tm iH、iL、mH、mLDesign parametersMode of
6、 intercoolingWith incomplete interstage coolingWith complete interstage cooling1Tk、T0、tm、t4pk、p0、pmTkTHTkpk ;tm pmT0TL-T0p0 ;t4tm2t2、t7 h2h1（h2sh1）/id;h7h6（h7sh6）/igt6h6h3（h2h3）qmL/qmHt6t32/28/202393.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.1 With incomplete interstage cooling 中间不完全冷却 1 2 6 7 9
7、 4 5 10 3 qmgqmd qmd qmg qmHh6qmLh2（qmHqmL）h3 h6h3（h2h3）qmL/qmH 2/28/2023103.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.1 With incomplete interstage cooling 中间不完全冷却qmHh9qmLh4（qmHqmL）h3 qmHqmL（h3h4）/（h3h9）1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg 2/28/2023113.2.2.2 Double-throttle cycles（二）二次节流循环 3.2.2.2.
8、2 With complete interstage cooling 中间完全冷却qmHh9qmLh2qmLh4qmHh3 qmHqmL（h2h4）/（h3h9）2 1 6 7 9 4 5 10 3 qmd qmd qmg 2/28/2023123.2.2 Design type analysis 二、设计型分析 3.2.2.2 Double-throttle cycles（二）二次节流循环User specified:TH、TL、Q0Designer chosen:iH、iL、mH、mL Design parametersMode of intercoolingWith incomplete
9、 interstage coolingWith complete interstage cooling3q0、qkwL、wHq0h1h4 、wLh2h1qkh7h9 、wHh7h64qmLqmLQ0/q0Q0/（h1h4）（3-43）(h3h4)/(h3h9)(h2h4)/(h3h9)5qmH qmHqmL (3-47)qmHqmL (3-47)2/28/2023133.2.2 Design type analysis 二、设计型分析 3.2.2.2 Double-throttle cycles（二）二次节流循环User specified:TH、TL、Q0Designer chosen:iH
10、、iL、mH、mL Design parametersMode of intercoolingWith incomplete interstage coolingWith complete interstage cooling6PtL PtLqmLwLqmL（h2h1）（3-44）PtH PtHqmHwHqmgH(h7h6)（3-48）PtPtPtLPtHqmH/qmdL1(h3h4)/(h3h9)(h2h4)/(h3h9)7Q0/Pt(h1h4)/(h2h1)+(h7h6)（3-49）8QkQkqmHqkqmH（h7h9）9QmQmqmL（h9h4）2/28/2023143.2.2.2 Do
11、uble-throttle cycles（二）二次节流循环 3.2.2.2.3 With a interstage temperature heat exchanger 具有中温蒸发器qmL h2+qmH h9+qmm h3=qmL h4+qmH h3+qmm h4qmm=Qm/(h3-h4)；qmH qmL+qmm)()(93439342hhhhqqhhhhqqmdmmmdmg（3-57）qmdqmgqmmqmgqmd+(h3h4)/(h3h9)qmm)()()()(12374341hhqhhqhhqhhqmdmgmmmd（3-58）2/28/2023153.2.2 Design type
12、analysis 二、设计型分析3.2.2.3 Summy（三）小结中间冷却方式中间冷却方式无中间冷却无中间冷却中间不完全冷却中间不完全冷却中间完全冷却中间完全冷却一次节流一次节流简化设备的场合简化设备的场合绝热指数小（绝热指数小（FreonFreon）绝热指数大（绝热指数大（R717R717）二次节流二次节流离心式回油（离心式回油（FreonFreon）离心式回油（离心式回油（R717R717）2 1 6 7 9 4 5 10 3 qmd qmd qmg 1 2 6 7 9 4 5 10 3 qmgqmd qmd qmg 3.2 Two-stage vapor compression sys
13、tems3.2.1 Introduction3.2.2 Design type analysis3.2.2.1 Single-throttle cycles 3.2.2.2 Double-throttle cycles 3.2.3 Operation type analysis第二节第二节 两级蒸气压缩制冷循环两级蒸气压缩制冷循环一、绪论二、设计型分析（一）一次节流循环（二）二次节流循环三、操作型分析2/28/202317 opt -10 -8 -6 -4 -2 0 tm/tmopt 0 3.2.2 Design type analysis 二、设计型分析 3.2.2.4 Determinat
14、ion of interstage temperature（四）中间温度的确定f(Tk、T0、Tm)Tmopt f(max)opt f(Tk、T0、Tmopt)（3-64）HLHLmLmHLmLHmHvtLvtHvvvvqqvqvqqq131313qvsqmv1 qvtTm f(、Tk、T0)f(Tk、T0、Tm)2/28/2023183.2.3 Operation type analysis 三、操作型分析 An exampleqvtL=566m3/hqvtH=283m3/h=0.5tm=-7.81opt-15-12-8-5-13 tm/tmopt0opt-15-12-8-5-13 tm/t
15、mopt0=0.5HLHLmLmHLmLHmHvtLvtHvvvvqqvqvqqq131313Tm f(、Tk、T0)f(Tk、T0、Tm)2/28/2023193.2.3 Operation type analysis 三、操作型分析 3.2.3.1 Change of volume flow ratio（一）体积流量比变化 increases,Tk and T0 are constantpm Tm s opt -10 -8 -6 -4 -2 0 tm/tmopt 0 Tm f(、Tk、T0)2/28/2023203.2.3 Operation type analysis 三、操作型分析 3
16、.2.3.2 Change of condensing temperature（二）冷凝温度变化Tk increases,and T0 are constant q0,qmL Q0=qmLq0 H pm Tm;qmH w=wL+wH PsqmLwL+qmHwH?q0/w HLvtLvtHvvqq13(h2h4)/(h3h9)2/28/2023213.2.3 Operation type analysis 三、操作型分析 3.2.3.3 Change of evaporating temperature（三）蒸发温度变化T0 decreases,and Tk are constant q0、qm Q0qmLq0 L L pm Tm w=wL+wH PsqmLwL+qmHwH?q0/w(h2h4)/(h3h9)HLvtLvtHvvqq132/28/2023223.2.3 Operation type analysis 3.2.3.Chang of evaporating temperatureT0 increases,and Tk are constant p0 、pm pmpk Psgmax(pk/pm3,pm450kPa)Psdmax(pm/p03,or t0=t0b)2 1 6 7 9 4 5 10 3 qmd qmd qmg qmg
