螺旋管内流动沸腾传热系数关联式拟合与误差分析

为了发展适于螺旋管内流动沸腾传热系数关联式,基于流动沸腾传热机理,引入参数D_n数来修正复杂管道对传热系数的影响,并经过回归计算确定D_n数的指数,从而发展了螺旋管内流动沸腾传热系数关联式。进一步分析了传热系数预测值与实验值的偏差随流量、干度的变化情况。利用以R134a为介质的螺旋管传热实验数据验证了该关联式的适用性,并采用平均相对误差(the mean relative error, MRE)和均方根误差(the root mean square error, RMSE)来衡量预测结果的准确性,计算出MRE在8.23%范围内,RMSE为0.532。该平均相对误差值和均方根误差值都比较小,表明回归计算结果符合要求。因此,复杂管道引入参数D_n数建立传热系数关联式是非常适用的,并值得推广应用。

Fitting heat transfer coefficient correlation on flow boiling and error analysis for the helically coiled tube

In order to develop flow boiling heat transfer coefficient correlations for helically coiled tube, based on the mechanism of flow boiling heat transfer. The D_n factor was introduced to consider complex pipeline effects on flow boiling heat transfer. The index of the D_n factor was gained by using the regression method. And relation of the ratio of the experimental and predicted values with the mass flow rate and vapor quality was further analyzed. A new heat transfer coefficient correlation of flow boiling in helically coiled tube was developed. The applicability for the heat transfer coefficient correlation was validated by experimental data of flow boiling heat transfer in helically coiled tube with R134a. The MRE and the RMSE were used to measure the accuracy of regression results, with MRE and RMSE being 8.23% and 0.532, respectively. The MRE and the RMSE were small, the regression results conformed to the requirements. Therefore, the method is very applicable, and is worthy of popularization.