为了明确竖直矩形窄通道内各阶段流动沸腾的换热特性，优化换热器性能，以去离子水为工质，对尺寸为720 mm×250 mm×3.5 mm的单面电加热竖直矩形窄通道内的流动沸腾换热进行实验研究，分析了质流密度、进口温度、热流密度对流动沸腾局部换热特性的影响。并在已有流动沸腾传热关联式的基础上，对实验数据进行非线性回归分析，得到适用于实验工况下的新流动沸腾传热关联式。结果表明：质流密度增大对流动沸腾段换热特性有强化作用，对核态沸腾段换热特性有削弱作用；热流密度对核态沸腾影响剧烈，但对流动沸腾的影响不明显；入口温度越高，流体会越早进入过冷沸腾阶段，但对局部传热系数的影响不明显；新流动沸腾传热关联式与实验值的平均相对误差为23.87%，其中74.19%的预测值在±25%内，83.87%的预测值在±50%以内，能很好地预测本实验工况下矩形窄通道内流动沸腾的局部传热系数。

In order to clarify the heat transfer characteristics of flow boiling in a narrow vertical rectangular channel at each stage and optimise the performance of the heat exchanger, an experimental study was carried out on the flow boiling heat transfer in a singlesided electrically heated narrow vertical rectangular channel with dimensions of 720 mm × 250 mm × 3.5 mm, using deionised water as the working medium, and the effects of mass flux, inlet temperature and heat flux on the local heat transfer characteristics of flow boiling were analyzed. Based on the existing flow boiling heat transfer correlation formula, a nonlinear regression analysis of the experimental data was carried out to obtain a new flow boiling heat transfer correlation formula applicable to the experimental conditions. The results show that the increasing mass flux has a strengthening effect on the heat transfer characteristics of the flow boiling section and a weakening effect on the heat transfer characteristics of the nucleate boiling section; the heat flux has a strong effect on the nucleate boiling but not on the flow boiling; the higher the inlet temperature is, the earlier the fluid will enter the subcooling boiling stage, but the effect on the local heat transfer coefficient is not obvious; the average relative error between the new flow boiling heat transfer correlation formula and the experimental value is 23.87%, of which 74.19% of the predicted values are within ±25%, and 83.87% of the predicted values are within ±50%, which can well predict the local heat transfer coefficient of flow boiling in a narrow rectangular channel under this experimental condition.

TK124

上海市动力工程多相流动与传热重点实验室窄通道内液膜生成机理研究项目(2019KJFZ01)