【作者】 董茂林；

【导师】 童明伟；

【作者基本信息】 重庆大学 ， 制冷及低温工程， 2002， 硕士

【摘要】 由于CFC_s、HCFC_s类制冷剂对环境的破坏，寻找新的环保替代工质并把其推广应用成为目前一项较为迫切的工作。纯天然工质丙烷(HC290)，是一种很有前途的制冷剂替代物，已往的文献中对它进行了不少的研究，但将这种新型绿色环保工质推广应用，目前的研究成果还远远不够。 本文在分析研究国内外有关替代工质、制冷工质及其含油混合物管内凝结性能研究现状的基础上，对纯天然工质丙烷(HC290)与润滑油Suniso 3GS的混合物饱和温度、水平微肋管内凝结过程的传热及流阻特性进行了实验研究分析。实验的工况范围：含油率ω=1.95％～5.28％，质量流率G=40～220kg/m~2·s，凝结温度t=40～45℃，实验段入口干度为1，出口干度0.1～0.25。得出以下结论： (1)制冷剂HC290含油混合物的饱和温度高于相同压力下纯工质的饱和温度，这个温度差，也就是文中所谓的制冷剂含油混合物的过热温度随混合物质量含汽率、含油浓度的增加而增加，而饱和压力对过热温度的影响不大。文中应用混合物液相中油浓度的变化对这一现象进行了解释。 (2)关于HC290含油混合物水平微肋管内的冷凝换热特性的研究表明： a)随着质量流率的增加，混合物微肋管内冷凝平均换热系数增加。 b)不同含油率下，冷凝平均换热系数随着质量含油率的增加而降低。 c)同一含油率下，冷凝温度对平均换热系数几乎没有影响。 (3)由于制冷剂含油混合物过热温度的存在，使其具有两种不同的饱和温度定义，一种是所测实际温度，另一种是所测压力对应纯工质的饱和温度，文中就这两种饱和温度定义下的冷凝平均换热系数进行了比较，发现后者大于前者。 (4)将实验所得冷凝平均换热系数和已往经验关系式比较，得出了适用于本实验的相应经验关系式，实验数据点均落在关系式预测值±30％内。 (5)HC290含油混合物微肋管内凝结过程阻力性能实验表明，润滑油浓度的增加对混合物凝结压降影响不大。更多还原

【Abstract】 Owing to the negative influence of CFC and HCFC refrigerant on environment,seeking and using natural substitutes for CFC and HCFC refrigerant has become more and more urgent. Propane (HC290),a new natural refrigerant,is one of the most promising substitutes. Much information concerning HC290 is available in the present literature,however a great deal of work is still needed to do for using it properly.On the basis of the investigation on the related literature of new refrigerant substitutes,the in-tube condensation of refrigerant and refrigerant-oil mixtures,this paper investigates the saturated temperature of HC290-oil mixtures,condensation heat transfer and pressure drop characteristics in a horizontal micro-fin tube for it. The experimental conditions are as follows:the oil concentration is 1.95%-5.28%,mass flux is 40-220 kg/m2 s,and the condensation temperature is from 40C to 45C,the vapor quality is 1 at the inlet of the test section and 0.1-0.25 at the outlet of the test section. The conclusions reached are as follows:(1) The saturated temperature of refrigerant-oil mixture is higher than that of pure refrigerant at a same pressure. The temperature difference,which is called superheat temperature of refrigerant-oil mixture,increases as the oil concentration and the vapor quality are increased at a certain saturated pressure and pressure has negligible effect on the superheat temperature of the mixture. This is explained with the viewpoint of oil concentration change in the liquid phase of the refrigerant-oil mixture.(2) The investigation on the condensation heat transfer characteristics in a horizontal micro-fin tube for HC290-oil mixture shows:a) The condensation heat transfer coefficient of the mixture increases with the increasing of the mass flux.b) The mean condensation heat transfer coefficient decreases with the increase of the oil concentration.c) The condensation temperature has negligible effect on the mean heat transfer coefficient at a same oil concentration.(3) The saturated temperature of refrigerant-oil mixture has different definitions because of the superheat temperature of the mixture. One is the real saturatedtemperature of the mixture and the other is the saturated temperature of pure refrigerant corresponding to the tested pressure of the mixture. In this paper,the heat transfer coefficients based on the two different saturated temperatures are compared and the results showed the latter is larger.(4) A heat transfer correlation is developed by comparing the experimental data with the past correlations. And the deviation between the predicted and experimental values is 30%.(5) The experiment on the condensation resistance characteristics of HC290-oil mixture shows the oil concentration has negligible effect on the pressure drop of the mixture.更多还原