微通道冷凝器平行扁管温度不均匀分布的实验研究

文献出处：第六届全国制冷空调新技术研讨会 年份：0

论文摘要：摘 要： 管内制冷剂流量分配不均对微通道换热器有重要影响，会导致其能力退化。由于两相流体和集管耦合的复杂性，许多目前研究主要集中在实验模拟分析管内流量分配特性。本文通过测试扁管温度分布，来评价微通道冷凝器管内流量分配特性。通过制造一台安装有6流程40扁管微通道冷凝器的窗口式R22空调样机，并在三种工况下利用38支T型热电偶测试了19根冷凝器扁管两端的温度分布。实验表明，无论单相和两相流，同一流程各扁管温度分布都不均匀。同一流程各扁管的入口制冷剂温度随着制冷剂在竖直集管内的流动而降低。在GB/T 7725-2004规定的额定制冷和最大运行等3种工况下，同一流程不同扁管最大入口温差存在于流程1，分别是5.36℃，6.35℃，8.49℃,而最大出口温差存在于流程5，分别是10.04℃，8.72℃， 8.18℃。温度的不均匀分布间接证实了显著的制冷剂流量不均匀分配。 关键字: 温度不均匀分布 制冷剂不均匀分配 两相流 微通道换热器 Experimental Research on Uneven Temperature Distribution in Parallel Flat Tubes of 6-pass Microchannel Condenser Du Zhengjian Lu Hongliang Shu Zhaohui Department of Refrigeration Power, Huazhong University of Science nbsp; Abstract: Refrigerant flow maldistribution in multiple flat tubes is important for microchannel heat exchanger, which leads to performance deterioration and capacity degradation. Due to the complexity of two-phase and header-tube junction, much previous effort focused mainly on experimental simulation of flow maldistribution in tubes. Testing temperature distribution of tubes was proposed to evaluate flow maldistribution in microchannel condenser. One 40-tube 6-pass microchannel condenser equipped in a window type R22 air conditioner prototype was fabricated and tested under three operating condition, temperature distribution at both ends of 19 parallel flat tubes in the condenser was acquired by 38 T-type surface thermocouples. From the experiment, it was found that temperature distribution in multiple tubes of the same pass is uneven both in single phase and in two-phase: inlet refrigerant temperature of each horizontal tube in the same pass decreases along refrigerant flow in the vertical manifold. For the standard rating conditions and the maximum operating condition required by GB/T 7725-2004, the maximum inlet temperature differences between the tubes of the same pass are 5.36℃,6.35℃, 8.49℃ in the 1st pass while the maximum outlet temperature differences are 10.04℃, 8.72℃, 8.18℃ in 5th pass. The uneven temperature distribution verified the obvious refrigerant flow maldistribution indirectly. Keywords: uneven temperature distribution; flow maldistribution; two-phase flow; microchannel heat exchanger