CHF is the maximal limit of heat flux in boiling heat transfer, therefore, it is a crucial parameter that has a fundamental impact on the security and economy of the nuclear system. An experimental investigation was carried out in the present study to identify the dominant CHF mechanism in a narrow rectangular channel at different gap sizes (2 mm and 3 mm). The visualization experiments were performed at pressures ranging from 1 to 4 MPa, inlet subcooling from 60 to 120 K, and mass flux of 350–2000 kg/(m²·s). A theoretical model of DNB-type CHF has been proposed through visualization phenomena and bubble dynamics analysis. A set of constitutive correlations is developed to close the model. An assessment of the new model has been conducted using the experimental data for the upward flow in a vertical narrow rectangular channel. The predicted results show good accuracy, which is less than 30% relative to the present CHF data and other CHF data under high-pressure conditions.

CHF是沸腾传热中热通量的最大限制，因此，它是一个关键参数，对核系统的安全性和经济性具有根本影响。在本研究中进行了一项实验研究，以确定在不同间隙尺寸（2 mm和3 mm）的狭窄矩形通道中的主要CHF机制。可视化实验是在1至4 MPa的压力，60至120 K的入口过冷以及350–2000 kg /（m ^2的质量通量）下进行的。·s）。通过可视化现象和气泡动力学分析，提出了DNB型CHF的理论模型。开发了一组本构相关来关闭模型。已经使用垂直狭窄矩形通道中向上流动的实验数据对新模型进行了评估。预测结果显示出良好的精度，相对于当前的CHF数据和在高压条件下的其他CHF数据而言，其准确性不到30％。