FUNDAMENTAL STUFY OF A SMALL-SCALE HEAT PUMP

小型热泵的基础研究

基本信息

批准号：
11450083
负责人：
HIHARA Eiji
金额：
$ 4.48万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450083/
关键词：
Heat pump Heat exchanger Small diameter tube Micro-channel 微小機構圧縮機

项目摘要

Size reduction of heat exchangers is one of the most important technologies for micro-scale heat pumps. In order to develop small-scale heat pumps, in this study fundamental research of small-scale heat exchangers were executed, which include heat transfer and pressure loss characteristics in small diameter heat transfer tubes, distribution of gas liquid two-phase flow at a T-junction and measurement and simulation of heat exchangers with small diameter tubes.(1) For boiling heat transfer and pressure drop characteristics inside small diameter tubes, the diameter of heat transfer tubes were varied between 0.5 and 3 mm ID, and the HFC134a was selected as a working fluid. For smaller diameter tubes than 1mmID, heat transfer coefficients were deteriorated due to dry out in the quality range higher than 0.5. When the vapor quality at the inlet of the evaporator is less than 0.1, the flow pattern becomes intermittent and heat transfer performance decreases significantly.(2) Phase separation of gas-liquid two-phase flow at an impacting tee was investigated experimentally and theoretically. It was found that if the flow rates in the branches were different, phase separation was observed. Based on the principle of minimum energy dissipation, a thermodynamic model was derived. The results of the model were qualitatively in good agreement with the experimental behavior of impacting flows.(3) The performance of fined small tube heat exchangers was investigated both experimentally and theoretically. The Inner diameters of tubes were 1.0mm, 2.1mm and 4.0mm. Calculation results show that the volume of a 2.0mm tube heat exchanger can be reduced to 33% of that of a 4mm tube heat exchanger with the same capacity. The flow distribution in a branching unit strongly affects the exchanged heat.

尺寸减小热交换器是微型热泵最重要的技术之一。为了开发小规模的热泵，在这项研究中，执行了小尺度热交换器的基本研究，其中包括小直径传热管中的热传递和压力损失特征，在T型和测量和测量中的气体液体液体两度流量的分布以及用小型散热器进行热量传播的液体变速箱的传热特征。试管在0.5至3 mM ID之间变化，并选择HFC134A作为工作流体。对于高于1mmid的直径较小的管，由于在高于0.5的质量范围内干燥，传热系数会恶化。当蒸发器入口处的蒸气质量小于0.1时，流动模式就会间歇性，热传递性能显着降低。（2）在实验和理论上研究了撞击TEE上气体液态两相流量的相位分离。发现如果分支中的流速不同，则观察到相位分离。根据最小能量耗散的原理，得出了热力学模型。该模型的结果与影响流的实验行为质量吻合。（3）在实验和理论上对被罚款的小管热交换器的性能进行了研究。管的内径为1.0mm，2.1mm和4.0mm。计算结果表明，2.0mm管热交换器的体积可以减少到具有相同容量的4mm管热交换器的体积。分支单元中的流量分布强烈影响交换的热量。