《制冷与低温原理》课件A第一章 制冷与低温的热力学基础 1 (1.1.1)19

1、1 Thermodynamic fundamentals of refrigeration and cryogenic engineering1.1 Methods of refrigeration1.1.1 Refrigeration by phase change第一章 制冷与低温的热力学基础第一节 制冷的方法一、相变制冷8/1/20222William Cullen and his student Joseph Black ( 1755, English ) IceEtherVacuum pumpEtherVacuum pump8/1/20223Refrigeration by phas

2、e change 相变制冷MeltingSublimatingPhase changePressure dropNormal Boiling PointCritical PointTb（K）tb（）Tc（K）tc（）C2H6O351.578.3516.2243.0Ether307.834.6467.2194SO2263.2-10430.7157.5NH3239.9-33.3406.2133.0CO2194.8-78.4304.331.1C2H4169.5-103.7282.59.3CH4111.7-161.5190.5-82.7O290.3-182.9154.8-118.4N274.4-198

3、.8126.3-146.9H220.4-252.833.3-239.9He4.3-268.95.3-267.98/1/20224TaTTcTbTf1atmRefrigeration by phase change 相变制冷Melting Vaporizingdukinetic = du - dupotential 0Pressure dropPhase changedu = (hg - u)dm/m (hg - hl)dm/m = dm/m 0The first law: Q = dU + W + (h+c2/2+gz)dmout - (h+c2/2+gz)dminSince: (hdm)ou

4、t= hgdmThus: -hgdmout =hgdm = dU= d(mu) = mdu +udm mdu = (hg - u)dm8/1/20225TaTTcTbTf1atmVaporizingRefrigeration by phase change and pressure drop相变制冷 EvaporatingSublimatingMelting8/1/20226TaTaTaTaTf1atmNormal boiling point and saturated passure 标准沸点和饱和压力Normal Boiling PointCritical PointTb（K）tb（）Tc

5、（K）tc（）C2H6O351.578.3516.2243.0Ether307.834.6467.2194SO2263.2-10430.7157.5NH3239.9-33.3406.2133.0CO2194.8-78.4304.331.1C2H4169.5-103.7282.59.3CH4111.7-161.5190.5-82.7O290.3-182.9154.8-118.4N274.4-198.8126.3-146.9H220.4-252.833.3-239.9He4.3-268.95.3-267.9EtherO2、 N2 H2、 HeNH3CO28/1/20227TaTTcTbTf1atm

6、M. Van Marum ( 1787, Holland ) LiquefyingNH3p1/p2=V2 /V1Boyles law波意尔-马略特定律NH3RefrigeratingCooling8/1/20228TaTaTaTaTf1atmliquefaction by pressurization and phase change by underpressure 加压液化和降压相变Normal Boiling PointCritical PointTb（K）tb（）Tc（K）tc（）C2H6O351.578.3516.2243.0Ether307.834.6467.2194SO2263.

7、2-10430.7157.5NH3239.9-33.3406.2133.0CO2194.8-78.4304.331.1C2H4169.5-103.7282.59.3CH4111.7-161.5190.5-82.7O290.3-182.9154.8-118.4N274.4-198.8126.3-146.9H220.4-252.833.3-239.9He4.3-268.95.3-267.9EtherO2、 N2 H2、 HeNH3CO28/1/20229Cascade systems and Permanent gases复叠式系统和永久气体Normal Boiling PointCritical

8、 PointTb（K）tb（）Tc（K）tc（）C2H6O351.578.3516.2243.0Ether307.834.6467.2194SO2263.2-10430.7157.5NH3239.9-33.3406.2133.0CO2194.8-78.4304.331.1C2H4169.5-103.7282.59.3CH4111.7-161.5190.5-82.7O290.3-182.9154.8-118.4N274.4-198.8126.3-146.9H220.4-252.833.3-239.9He4.3-268.95.3-267.9TaTaTaTaTf1atmEtherO2、 N2 H2、

9、 HeNH3CO2C2H4NH32000 atm8/1/202210C. C. de La Tour ( 1821, French ) , M. Faraday ( 1823, English ) and critical pointsAlcohol 119atmGlass ball Liquid chlorineChloride CrystalsCoolingCooling8/1/202211C. C. de La Tour ( 1821, French ) , M. Faraday ( 1823, English ) and critical pointsTaTf1atmTTcTbVaporizingAlcohol 119atmGlass ball 63atm, 243Van der Waals (1873, Holland )论气态和液态的连续性Liquid chlorineChloride CrystalsCoolingTaTTcTbTf1atm8/1/202212Guillaume Amontons (1663-1705, French ) and the absolute zeroAmontons Law: p1/p2=T1 /T2查理定律 p1/T1= (p1 - p2) / (T1 - T2) = p/T(p100 1.417p0 )Tzero= - 240 1