Abstract:

The influence of concentration of lubrication oil and structure of metal foam on the nucleate pool boiling heat transfer characteristics of refrigerant/oil mixture on metal foam covers was investigated experimentally.Three copper foams, 10 ppi/90% porosity, 10 ppi/95% porosity and 30 ppi / 98% porosity with the thickness of 5 mm, were used in this study.The refrigerant is R113 and the oil is VG68 with concentrations from 0 to 5%.The experimental results indicate that the pool boiling heat transfer coefficient on copper covers is larger than that on flat heated surface, with a maximum increase of 1.6 times under the experimental conditions.The presence of oil deteriorates the pool boiling heat transfer on copper foam covers, decreased by 15% or less under the experimental conditions.The deterioration of oil on nucleate pool boiling heat transfer is less on copper foam covers than on a flat heated surface.A correlation for predicting the nucleate pool boiling heat transfer coefficient of refrigerant/oil mixture on metal foam covers is developed, and it agrees with 95% of the experimental data within a deviation of ±10%.

Key words: 泡沫金属, 池沸腾, 制冷剂, 润滑油, 关联式

摘要：

实验研究了制冷剂/润滑油混合物在泡沫金属加热表面核态池沸腾的换热特性，分析了润滑油浓度和泡沫金属结构对池沸腾换热特性的影响。实验使用3种结构参数的泡沫金属作为加热表面，其参数分别为10 ppi/90%孔隙率、10 ppi/95%孔隙率和30 ppi/98%孔隙率，厚度均为5 mm。实验使用的制冷剂为R113，润滑油为VG68，润滑油浓度为0～5%。实验结果表明：泡沫金属的存在极大提高了制冷剂/油混合物的池沸腾传热系数，最多提高1.6倍；润滑油的存在恶化制冷剂在泡沫金属加热表面池沸腾的换热特性，传热系数最多降低

关键词: 泡沫金属, 池沸腾, 制冷剂, 润滑油, 关联式