《制冷与低温原理》课件A第一章 制冷与低温的热力学基础 2 (1.1.2)21

1、1.1 Methods of refrigeration1.1.1 Refrigeration by phase change1.1.2 Refrigeration by gas expansion Refrigeration by gas release第一节 制冷的方法一、相变制冷二、气体膨胀制冷1. 绝热放气制冷8/1/20222Cascade systems and Permanent gases复叠式系统和永久气体Normal Boiling PointCritical PointTb（K）tb（）Tc（K）tc（）C2H6O351.578.3516.2243.0Ether307.8

2、34.6467.2194SO2263.2-10430.7157.5NH3239.9-33.3406.2133.0CO2194.8-78.4304.331.1C2H4169.5-103.7282.59.3CH4111.7-161.5190.5-82.7O290.3-182.9154.8-118.4N274.4-198.8126.3-146.9H220.4-252.833.3-239.9He4.3-268.95.3-267.9TaTaTaTaTf1atmEtherO2、 N2 H2、 HeNH3CO2C2H4NH32000 atm8/1/20223L. Galletet ( Dec., 1877,

3、 French ) and liquefaction of oxygenO2 300atmTapSO2 -29TaTTcTbTf1atmLiquefying8/1/20224R. Pictet ( Dec., 1877, Swiss ) and liquefaction of oxygenO2 320atm, -140TapCO2SO2Normal Boiling PointCritical PointTb（K）tb（）Tc（K）tc（）SO2263.2-10430.7157.5CO2194.8-78.4304.331.1O290.3-182.9154.8-118.48/1/20225Z. F

4、. Wroblewski, K. S. Olszewski (1883, Poland )Oxygen 320atm, -140TapCO2SO2Liquid O2(-130)C2H4O2(320atm)Liquid chlorineChloride CrystalsCooling8/1/20226Z. F. Wroblewski, K. S. Olszewski (1883, Poland ) and M. Faraday ( 1823, English ) TaTcTbTf1atmO2Liquid O2(-130)C2H4O2(320atm)ChlorineNormal Boiling P

5、ointCritical PointTb（K）tb（）Tc（K）tc（）SO2263.2-10430.7157.5CO2194.8-78.4304.331.1O290.3-182.9154.8-118.4Liquid chlorineChloride CrystalsCooling8/1/20227 Refrigeration by gas releasedukinetic 0p、vTh、udu = (h - u)dm/m= pvdm/m 0The first law: Q = dU + W + (h+c2/2+gz)dmout - (h+c2/2+gz)dmindul = (hg - ul)

6、dm (hg - hl)dm = dm/m 膨胀作功 低压气体排出汽缸A 压缩过程 B 冷却过程 C 回热过程 D 膨胀过程8/1/202211Refrigeration by a work-producing device等熵膨胀制冷u = upotential + ukineticdu = -W /m 0dukinetic 0The first law: Q = dU + WdU = -W 膨胀作功 低压气体排出汽缸upotential 08/1/202212Differential (integral) isentropic expansion coefficient微分（积分）等熵效应

7、p、vTh、uD 膨胀过程：高压气体进入汽缸 膨胀作功 低压气体排出汽缸微分等熵效应：积分等熵效应：8/1/202213Refrigeration by gas expansion气体膨胀制冷（等熵膨胀和绝热放气制冷）Wmpv绝热放气等熵膨胀8/1/202214TaTaTaTaTf1atmNormal boiling points and critical points标准沸点和临界点Normal Boiling PointCritical PointTb（K）tb（）Tc（K）tc（）C2H6O351.578.3516.2243.0Ether307.834.6467.2194SO2263.2

8、-10430.7157.5NH3239.9-33.3406.2133.0CO2194.8-78.4304.331.1C2H4169.5-103.7282.59.3CH4111.7-161.5190.5-82.7O290.3-182.9154.8-118.4N274.4-198.8126.3-146.9H220.4-252.833.3-239.9He4.3-268.95.3-267.9EtherO2、 N2 H2、 HeSO2CO21.1 Methods of refrigeration1.1.1 Refrigeration by phase change1.1.2 Refrigeration

9、by gas expansion Refrigeration by gas release Refrigeration by a work-producing device Refrigeration by Joule-Thomson expansion第一节 制冷的方法一、相变制冷二、气体膨胀制冷绝热放气制冷等熵膨胀制冷节流膨胀制冷8/1/202216Joule-Thomson effect ( 1852, English ) 焦耳-汤姆逊效应The first law: q = h + w + c2/2 + gzh = 0 h1 = u1 + p1v1h2= u2 + p2v2uK p1v

10、1p2v2 uPh1 = h28/1/202217Differential (integral) Joule-Thomson coefficient 微分（积分）节流效应微分节流效应：积分节流效应：h1 = h2uK p1v1p2v2 uP8/1/202218Refrigeration by Joule-Thomson expansion节流膨胀制冷CoolingHeatingIdeal gasReal gasInversion curseuK p1v1p2v2 uPTTaTcTbTf1atmExpansionh1 = h2微分节流效应：CoolingHeatingInversion curs

11、e8/1/202219Refrigeration by Joule-Thomson expansion节流膨胀制冷8/1/202220Inversion points转化曲线Normal Boiling PointCritical PointInversion PointTb（K）Tb（）Tc（K）Tc（）Tmax（K）tmax（）N274.4-198.8126.3-146.9604331H220.4-252.833.3-239.9204-69He4.3-268.95.3-267.946-227TTaTcTbTf1atmExpansionCoolingHeating8/1/202221J. P

12、erkins ( 1834, American )EvaporatorEtherCondenserCompressorExpansion valves压缩机冷凝器节流阀蒸发器8/1/202222Linde-Hampson cycle ( 1895, German-English )Recuperator8/1/202223Inversion points转化曲线Normal Boiling PointCritical PointInversion PointTb（K）Tb（）Tc（K）Tc（）Tmax（K）tmax（）N274.4-198.8126.3-146.9604331H220.4-25

13、2.833.3-239.9204-69He4.3-268.95.3-267.946-227TTaTcTbTf1atmHydrogenExpansion8/1/202224Sir J. Dewar ( 1898, English ) and liquefaction of hydrogen杜瓦和氢的液化Minds are like parachutes. They only function when they are open.Normal Boiling PointCritical PointInversion PointTb（K）Tb（）Tc（K）Tc（）Tmax（K）tmax（）N274.4-198.8126.3-146.9604331H220.4-252.833.3-239.9204-69He4.3-268.95.3-267.946-2278/1/202225H. K. Onnes ( 1908, Holland ) and liquefaction of helium氦的液化H2HeH2CH3ClC2H4O2Air8/1/202226Refrigeration by gas expansion气体膨胀制冷Wmpvpv8/1/202227Refrigeration by expansion of working substances工质膨胀制冷8