Abstract:

Microchannel heat exchangers (MCHXs) have the advantages of compact structure and high heat transfer efficiency. However, the performance of MCHXs may deteriorate due to the difficulty in defrosting water drainage when MCHXs are applied to heat pump air conditioners. The louver fins used in inserted microchannel heat exchanger add a special structure of drainage channel, which can improve the drainage performance of microchannel heat exchanger. In this paper, the structure of tubes with two-row fins is selected as the modelling object. The contact angle model of water droplets and the surface tension model are developed to predict the movement characteristic of water on the fin surface, and the proposed model is validated by the experiments. The simulation results show that, the effect of louver angle of the fins on the mass of retaining water is not obvious; the mass of retaining water increases with the increase of the louver number of the fins, and the water retention mass increases up to 31.89% as the louver number increases from 5 to 14.

Key words: inserted microchannel heat exchanger, water drainage model, louver angle, louver number

摘要：

微通道换热器结构紧凑、换热效率高，但应用于热泵空调器时，会出现排水困难从而造成性能恶化的问题。插片式微通道换热器通过在翅片上增加专门的排水槽结构，能够有效提升微通道换热器的排水性能。本文采用百叶窗型插片式微通道换热器的双翅片扁管结构作为几何建模对象，利用液滴接触角模型与表面张力模型来确定排水过程中液滴在翅片表面的运动过程，建立排水预测模型，并通过试验验证模型准确性。通过对不同开缝角度和开缝数量的百叶窗翅片排水性能进行模拟，发现翅片上残留水量与开缝角度没有明显的单调关系；翅片上残留水量随着开缝数量增加而增加；当开缝数量由5个增加到14个时，残留水量增大了31.89%。

关键词: 插片式微通道换热器, 排水模型, 开缝角度, 开缝数量