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对六根金属泡沫强化管在R134a工质饱和温度分别为35℃和40℃时的凝结传热进行了实验研究,分析了金属泡沫孔密度、厚度等结构参数对凝结传热性能的影响。研究表明:孔密度为130 ppi的强化管凝结传热效果最好,强化倍率最大为光管的3.06倍;金属泡沫材料厚度的增加会导致凝结传热过程恶化。通过对相同孔密度、不同饱和温度和金属泡沫厚度管型管外传热系数与壁面过冷度曲线的分析发现:130 ppi和80 ppi系列管强化传热机理相似,毛细作用比较明显;40 ppi管主要以类似低肋管的结构为强化手段。
Condensation heat transfer of six metal foam reinforced tubes at R134a working temperature of 35 ℃ and 40 ℃ respectively was studied. The influence of structural parameters such as density and thickness of metal foam on the heat transfer performance was analyzed. The results show that the condensation tube with a hole density of 130 ppi has the best condensation heat transfer efficiency and the maximum enhancement ratio is 3.06 times that of a light tube. The increase of the thickness of the metal foam will lead to the deterioration of the condensation heat transfer process. The analysis of heat transfer coefficient and wall undercooling curve of tube with the same hole density, different saturation temperature and thickness of metal foam shows that the mechanisms of heat transfer enhancement of 130 ppi and 80 ppi series tubes are similar and the capillary action is obvious; 40 ppi The main structure of the tube is similar to the low-cost tube as an enhancement.