Nozzle Track and CHF Prediction of Spray Cooling for Inclined Sprays

The tracks of the nozzles were studied during spray cooling with different inclination angles, based on the study of Visaria and the critical heat flux (CHF) criterion, which means that CHF will be achieved when the spray is configured on the condition that the spray impact area just inscribes a square test surface. The predictions of the tracks of the nozzles were made. It indicates that the nozzle tracks are parts of some ellipses as keeping the four borderline of the square test surface being the tangent line of the elliptical spray impact area. A new CHF model was established and new expression of CHF was derived based on the nozzle track model and the study of Visaria. The effects of spray inclination angle on CHIF were predicted. Simulation results indicate that CHF increases slightly with increasing inclination angle. The maximum difference of CHF of the three nozzles been simulated is about 13.1%. One reason for the difference between the established model and the results derived by Visaria is attributed to the difference of the spray impact area. The tracks of circular nozzles spraying onto a circular surface with inclination angles were discussed, and it shows that the tracks are parts of some circles. The tracks of foursquare nozzles spraying onto circular surface and foursquare surface were also discussed, and it shows that the tracks are parts of some circles. As a certain inclination angle and the same cone angle, foursquare nozzles have the largest impact area while there is a foursquare heated surface.