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主页 旧刊 有关人员 未来大会 American Society of Thermal and Fluids Engineering

ISSN 在线: 2379-1748

ISBN 打印: 978-1-56700-517-2 (Flash drive)

5-6th Thermal and Fluids Engineering Conference (TFEC)
May, 26–28, 2021 , Virtual

EFFECTS OF SURFACE WETTABILITY ON FROST NUCLEATION UNDER ENVIRONMENTAL CONDITIONS TYPICAL OF HEAT PUMP SYSTEMS

Get access pages 373-382
DOI: 10.1615/TFEC2021.cnd.032059

摘要

Frost growth on the finned structures of heat exchangers decreases the efficiency of air-source heat pumps when they run during winter months. Frost penalizes the heat transfer by adding thermal resistance to the fins, and increases pressure drop by restricting the free cross-sectional area for the air flow through the fins. Several experimental studies reported that coatings can be effective in mitigating frost growth. However, there is a lack of data that describe the frosting characteristics of fins with super-hydrophilic and super-hydrophobic coatings and operating within actual heat pump field type run conditions. This paper addresses this gap and presents new data of frost nucleation and growth on super-hydrophobic, super-hydrophilic, and bare aluminum flat surfaces under air forced convection conditions. A new experimental methodology was developed for re-establishing the initial dry state conditions of the surface, and improving the repeatability of frost nucleation by minimizing contamination from the environment. For every surface, changing the humidity had a small effect on nucleation and later frost growth behavior, while changing test plate temperature or air flow rate significantly affected the results. The wettability of the surface also affected the frost nucleation for some environmental conditions. In those tests, the super-hydrophobic surface had the longest freezing times, while the bare aluminum surface generally had the shortest freezing times. The super-hydrophilic surface also had a denser, colder frost layer than the super-hydrophobic surface.
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