扁管微小通道内R134a的沸腾换热试验

发布时间：2018-06-04 04:54

本文选题：微小通道 + 多孔扁管　；参考：《航空动力学报》2017年07期

【摘要】：搭建适用于多种结构微小通道的沸腾换热试验系统,研究了制冷剂R134a在当量直径分别为0.63mm和0.72mm的多孔扁管微小通道内的沸腾换热特性。试验参数包括制冷剂质量流率为82~621kg/(m~2·s),饱和压力为0.22~0.63MPa,干度为0~1;采用等热流密度方式加热,热流密度范围为9.7~64kW/m~2。结果表明:R134a在扁管内沸腾换热中,当干度在0~0.6区间时,微小通道的传热系数明显高于常规通道,换热类型主要为核态沸腾,传热系数随热流密度和饱和压力的增大而增大,与质量流率关系不大;当干度大于0.6之后,传热系数随着干度的增大急剧减小,且在此干度区间,传热系数受热流密度和饱和压力影响较小,而受质量流率的影响相对较大。利用该结论和公开文献中R134a沸腾换热试验数据对Gungor-Winterton公式进行改进,改进后的公式对所有试验点的平均相对误差为-1.17%,平均绝对误差为19.24%,预测精度有了明显提高。
[Abstract]:The boiling heat transfer characteristics of refrigerant R134a in a porous flat tube with equivalent diameters of 0.63mm and 0.72mm were studied. The experimental parameters include the refrigerant mass flow rate of 82~621kg/(m~2 sn, saturation pressure of 0.22g / 0.63MPa and dryness of 0 / 1, and the heat flux range of 9.7 ~ 64kW / m ~ (2) by isothermal heat flux method. The results show that the heat transfer coefficient of the small channel is obviously higher than that of the conventional channel when the dryness is in the range of 0 ~ 0.6, and the heat transfer coefficient increases with the increase of heat flux and saturation pressure, and the type of heat transfer is mainly nucleate boiling, and the heat transfer coefficient increases with the increase of heat flux and saturation pressure. When the dryness is greater than 0.6, the heat transfer coefficient decreases sharply with the increase of dryness, and in this dryness range, the heat transfer coefficient is less affected by the heat flux and saturation pressure, but by the mass flow rate. The Gungor-Winterton formula is improved by using this conclusion and the boiling heat transfer test data of R134a in the open literature. The average relative error of the improved formula for all test points is -1.17 and the average absolute error is 19.24. The prediction accuracy is obviously improved.
【作者单位】：南京航空航天大学航空宇航学院;
【分类号】：TB64

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