An experimental study of the CHF in a square channel with non-uniformly heated rod under low pressure and low flow conditions

Experimental research on critical heat flux (CHF) was carried out in a vertical square channel with non-uniformly heated rod at low pressure and low flow conditions. The influence of inlet subcooling on CHF was also investigated. The results showed that the CHF position of the non-uniformly heat flux distribution mainly appeared in the middle and lower part of the heater rod. More significantly, it was found that CHF was enhanced with the rise of the inlet subcooling. The CHF data measured in this experiment were also assessed with the commonly used CHF empirical correlations suitable for low pressure and low flow. The results indicated that the general correlations predicting for CHF of uniform heat flux distribution were not applicable for prediction CHF of nonuniform heat flux distribution and these correlations usually overestimated the experimental values. In addition, The F-factor approach proposed by Tong was used to predict the experimental data and the error predicted by F-factor were mostly between 30 % and 50 %. Finally, F-factor was modified based on experimental data and the error between the predicted value and experimental results was between 0 and 30 %, and most of the data was between 0 and 20 %.