Comparison of flow boiling heat transfer characteristics inside different enhanced heat transfer tubes
TANG Wei-yu1, CHEN Jing-xiang1, HAN Jin-cheng2, HE Yan2, LI Wei1, LIU Zhi-chun3
1. Department of Energy Engineering Zhejiang University, Hangzhou 310027, China;
2. School of Eletro-Mechanical Engineering Qingdao University of Science and Technology, Qingdao 266061, China;
3. School of energy and power engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Flow boiling heat transfer characteristics of refrigerant R410A in six disparate horizontal enhanced tubes and a plain circular tube were investigated experimentally. The experiment results were collected at a saturation temperature of 6℃, a mass velocity range of 80~350 kg/(m2s,) inlet vapor quality of 0.2 and outlet vapor quality of 0.9. Results indicate that the 3D tubes can augment heat transfer of evaporation substantially, and the enhanced ratio relative to the plain tube is in the range of 1.14 to 1.53. The dimple arrays on the surface of 3D tubes can augment interfacial turbulence, increase nucleation sites, irrupt boundary layer development and produce separation flow as well as secondary flow to intensify the heat transfer. There are apparent differences among the heat transfer coefficient of three micro-fin tubes, which can be attributed to different geometries of fins. In addition, the micro-fin tube whose ratio of the fin height with the liquid film thickness is close to unity has the best heat transfer performance, when they have an large enough helical angle.
TANG Wei-yu, CHEN Jing-xiang, HAN Jin-cheng, HE Yan, LI Wei, LIU Zhi-chun. Comparison of flow boiling heat transfer characteristics inside different enhanced heat transfer tubes. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2018, 52(6): 1216-1222.
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