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首页> 外文期刊>Experimental Thermal and Fluid Science: International Journal of Experimental Heat Transfer, Thermodynamics, and Fluid Mechanics >Two-phase flow patterns and heat transfer characteristics of R134a refrigerant during flow boiling in a single rectangular micro-channel
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Two-phase flow patterns and heat transfer characteristics of R134a refrigerant during flow boiling in a single rectangular micro-channel

机译：R134a制冷剂在单个矩形微通道中沸腾时的两相流型和传热特性

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摘要

In this paper, flow patterns and heat transfer characteristics of R134a refrigerant during flow boiling in a single rectangular micro-channel with 0.68 mm hydraulic diameter are investigated. In this experiment, heat transfer coefficients were studied at a heat flux range of 7.63-49.46 kW/m(2), mass flux range of 600-1400 kg/m(2) s, and saturation temperature range of 23-31 degrees C. Results show that there are six different flow patterns occurring during boiling of R134a refrigerants: bubbly flow, bubbly-slug flow, slug flow, throat-annular flow, churn flow, and annular flow. It is also found that flow pattern has a significant relation to heat transfer coefficients. In low heat flux range, variation of mass flux has no significant effect on the heat transfer coefficient. It corresponds to the nucleate boiling heat transfer mechanism in which its flow patterns are bubbly flow, bubbly-slug flow, slug flow, throat-annular flow, and churn flow. The heat transfer coefficient at higher saturation temperatures is greater than that of lower saturation temperatures. In high heat flux ranges, the heat transfer coefficient increases with increasing mass flux. It corresponds to the convective boiling heat transfer mechanism in which its flow pattern is annular flow. Increase of saturation temperature causes the heat transfer coefficient to decrease. At very high saturation temperature, a partial dry-out occurs that results in a lower heat transfer coefficient. (C) 2015 Elsevier Inc. All rights reserved.
机译：本文研究了R134a制冷剂在水力直径为0.68 mm的单个矩形微通道中沸腾时的流动方式和传热特性。在此实验中，研究了热通量范围为7.63-49.46 kW / m（2），质量通量范围为600-1400 kg / m（2）s和饱和温度范围为23-31摄氏度的传热系数结果表明，在R134a制冷剂沸腾期间会发生六种不同的流动方式：气泡流，气泡团流，团流，喉-环形流，搅动流和环形流。还发现，流型与传热系数有显着关系。在低热通量范围内，质量通量的变化对传热系数没有显着影响。它对应于成核沸腾传热机制，其中其流动方式为气泡流，气泡团流，团流，喉-环形流和搅动流。在较高饱和温度下的传热系数大于较低饱和温度下的传热系数。在高热通量范围内，传热系数随质量通量的增加而增加。它对应于对流沸腾传热机构，其中其流动方式为环形流动。饱和温度的升高导致传热系数降低。在非常高的饱和温度下，会发生部分变干，从而导致较低的传热系数。 （C）2015 Elsevier Inc.保留所有权利。

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