卧式螺旋管临界热流密度的流体模化

为检验经典的临界热流密度(critical heat flux, CHF)流体模化方法对于卧式螺旋管的应用效果,采用大功率直流电加热的方法对制冷剂HFC-134a在卧式螺旋管内的流动沸腾CHF进行了实验测试。通过运用Ahmad和Katto模型对实验测试数据和已有数据源进行模化计算发现:Ahmad和Katto模型确定的流量模化因子对于卧式螺旋管CHF的流体模化会产生较大的偏差,导致预测的CHF值高于实验结果。在实验数据分析的基础上提出了卧式螺旋管CHF流量模化因子的经验关联式。计算结果表明:应用该关联式对实验条件下卧式螺旋管CHF的预测偏差在±20%以内,其流体模化精度明显优于Ahmad和Katto模型。

Fluid-to-fluid modeling of critical heat flux in horizontal helically coiled tubes

In order to assess the effect of the classical fluid-to-fluid modeling technique of critical heat flux (CHF) applied to horizontal helically coiled tubes, CHF experiments for HFC-134a flow boiling in horizontal helically coiled tubes heated with high power DC source were carried out. The results of applying Ahmad and Katto model indicated that the flow scaling factor determined with the two models produced bigger errors for CHF modeling in horizontal helically coiled tubes, and both Ahmad and Katto model overestimated the experimental data. Based on the data analysis, an empirical correlation for flow scaling factor was proposed. The calculation results showed that this correlation predicted the CHF in horizontal helically coiled tubes under the experimental conditions within an error band of ±20％, and was obviously superior to Ahmad and Katto model in precision.