An experimental study was carried out to investigate the critical heat flux (CHF) during natural convective boiling in the uniformly heated

inclined tubes submerged in the saturated liquids at atmospheric pressure.The inner diameters of the test tubes varied from 100 mm to 400 mm;the heated lengths of the tubes ranged from 0.9 mm to 8 mm;the inclination angles varied from 90° to 30°. The test fluids were pure water and R-11.A semi-theoretical correlation used originally for predicting of the critical heat flux during natural convective boiling in vertical tubes was modified to predict the critical heat flux which occurs in the inclined tubes.The modified correlation agrees reasonably well with the present experimental data.