A correlation to evaluate critical heat flux in small diameter tubes under subcooled conditions of the coolant

A correlation is generated by applying regression analysis to the data under subcooled conditions from the literature to determine the critical heat flux in small diameter tubes less than 3 mm at different pressures for a wide range of system parameters. The correlation is accomplished for the model of slug flow in the tube considering the determining criteria for the formation of the slugs as vapor locks in the tubes leading to departure from nucleate boiling [DNB] conditions. It is observed that the correlation satisfies a wide range of system parameters. Application of the correlation to the data of larger diameter tubes revealed satisfactory agreement. Besides for saturated flow conditions of the coolant (x > 0), another generalized correlation is also proposed with reasonably good accuracy. Comparison of the present correlations with some of the recent correlations indicated satisfactory agreement supporting the validity of the criteria employed in the regression.