摘要
本文实验研究了R32在外径为19.05 mm的不锈钢喷砂管、凹坑管、凹坑/喷砂管以及光滑管管外环形区域蒸发换热特性,分析了质量流速(50~140 kg/(m^(2)·s))、干度(0.2~0.8)、饱和温度(279~288 K)对制冷剂换热的影响。结果表明:凹坑/喷砂管表面传热系数最高、凹坑管次之、光滑管最低;表面传热系数和摩擦压降均与质量流速成正相关,与饱和温度成负相关;高质量流速下平均干度对表面传热系数影响较大。引入强化因子η_(EF)和性能评价因子η_(PEF)对强化换热效果进行量化,凹坑/喷砂管结合了喷砂与凹坑表面的优点展现出最佳的蒸发换热性能,其η_(EF)值和η_(PEF)值最高可达2.84和2.31。喷砂与凹坑复合处理换热管表面,增加传热面积和汽化核心数量,提高湍流强度,拉伸减薄液膜促进管外蒸发换热。
The evaporation heat transfer characteristics of R32 in an annular area outside a stainless steel sandblasted tube,dimple tube,dimple/sandblasted tube,and smooth tube with an outer diameter of 19.05 mm were investigated,and the effects of the mass flux(50-140 kg/(m^(2)·s)),vapor quality(0.2-0.8),and saturation temperature(279-288 K)on the heat transfer coefficient were analyzed.The results show that the surface heat transfer coefficient is highest for the dimple/sandblasted tube,followed by the dimple tube,and lowest for the smooth tube.The surface heat transfer coefficient and frictional pressure drop are positively correlated with the mass flux and negatively correlated with the saturation temperature.The average vapor quality at high mass flux has a significanteffect on the surface heat transfer coefficient.The enhanced heat transfer effect was quantified by introducing the enhancement factorη_(EF)and the performance evaluation factorη_(PEF).The dimple/sandblasted tube combined the advantages of sandblasted and dimple surfaces,thus exhibiting the best evaporation heat transfer performance with the highestη_(EF)andη_(PEF)values of 2.84 and 2.31,respectively.The composite treatment of sandblasted and dimple heat transfer tube surfaces increases the heat transfer area and the number of vaporization cores,improving the turbulence intensity,such that the liquid film is stretched and thinned to promote evaporation outside the tube.
作者
吴俊杰
张江辉
高宇
程洪
李小利
何燕
Wu Junjie;Zhang Jianghui;Gao Yu;Cheng Hong;Li Xiaoli;He Yan(College of Mechanical and Electrical Engineering,Qingdao University of Science and Technology,Qingdao,266100,China;Shandong Henghui Energy Conservation Group Co.,Ltd.,Yantai,264003,China)
出处
《制冷学报》
CAS
CSCD
北大核心
2023年第3期95-102,118,共9页
Journal of Refrigeration
基金
国家自然科学基金(52176077)资助项目。
关键词
蒸发换热
复合微纳换热管
表面传热系数
摩擦压降
环形区域
evaporation heat transfer
composite micro-nano heat transfer tube
surface coefficient of heat transfer
frictional pressure drop
annular area
