STUDY ON THE CONDENSATION HEAT TRANSFER AND FLOW MECHANISM OF ALTERNATIVE REFRIGERANTS IN MICRO CHANNELS

替代工质微通道内冷凝传热及流动机理研究

基本信息

批准号：
11650226
负责人：
KOYAMA Shigeu
金额：
$ 2.3万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

In this study, it is aim to contribute to develop the very small and high performance condensers by clarifying the characteristics of local heat transfer and pressure drop in parallel channels with small diameter experimentally. The results are summarized as follows.(1) The Chischolm-Laird type correlation is proposed. In this correlation, the coefficient of second term changed from 21 to 4.81 and using X_<11> instead of X from the experimental results of total pressure drop with changing the outlet quality and mass velocity as a parameter. As a result, by using the correlation, predicted values are within ±30% error for most of all data of total pressure drop.(2) It is confirmed that the predicted values of the present correlation agree with the data of pressure distribution along the flow direction within ±30% error.(3) Compared the pressure drop data with the correlation of Mishima-Hibiki, the data agree with the correlation within ±30% by using X_<11>. The data also compared with t … More he correlation of Haraguchi et al. The data, however, don't agree with the correlation. In this study, hydraulic diameters of the tubes are 0.7 to 0.9, Mishima and Hibiki proposed the correlation based on the data of the tube with 1 to 4mm in diameter, but Haraguchi et al. proposed the correlation based on the tube with 8.5mm in diameter, therefore, the data agree with the correlation of Mishima-Hibiki, however, the data don't agree with the correlation of Haraguchi et al.(4) Compared the heat transfer data with the correlation of Moser et al., the data agree with the correlation within ±30% error in the case of the mass velocity above 300kg/m^2s, but disagree with the correlation in the case of the mass velocity below 200kg/m^2s. This reason is that Moser et al. didn't take account of the influence of the natural convective condensation heat transfer, and so, in the case of low mass velocity, when the influence of natural convection isn't small, it is hard to present the phenomena by using this correlation.(5) The data also disagree with the correlation of Haraguchi et al., which is based on the data of the tube of 8.5mm in diameter. However, using the correlation of Mishima-Hibiki for the pressure drop multiplier factor instead of the correlation of Haraguchi et al. for the pressure drop in their heat transfer correlation, most of all the data agree with this modified heat transfer correlation within ±50%. This reason is that Haraguchi et al. take account of both of the forced convective and natural convective condensation heat transfer, and so predicting accuracy becomes higher when the influence of tube diameter is took account of.(6) From the results (4) and (5), there is the influence of gravity even in the case of small diameter tubes when the mass velocity is low. Less

在这项研究中，这是通过阐明局部热传递的特征，这是一个非常高性能的竞争者。相关性是在此相关性中的。在总压力下降的所有数据中，当前相关性的大多数数据都与使用X_ <11>的±30％的误差相一致与t相关的数据也与t相关性，但该研究中的数据与基于直径1至4mm的数据相关性。但是，直径为8.5毫米，数据与Haraguchi等人的相关性不一致。低于200kg/m^2s的质量速度的相关性是，但大多数人都没有考虑到自然的对流冷凝热ansfer，因此自然对流的影响并不小。大多数数据都与±50％的改性相关性一致。），在质量速度较低的小直径管的情况下，重力事件事件的影响。