Investigation of Effects of Heater Tube Angle on the Pool Boiling Heat Transfer Coefficient

In this experimental study, the effects of slope changes on the heat transfer coefficient in pool boiling in deionized water have been investigated. The experiments were carried out in the average surface roughness of ۰.۲۱ µm on a copper cylinder by changing the surface slope including ۰°, ۵°, ۱۰°, ۱۵°, ۲۰°, ۲۵°, and ۳۰°. The range of heat flux was from ۲۱ to ۷۷ kW/m in atmospheric conditions. The results indicated that by increasing the heater slope, the departure frequency and bubble departure diameter on the heater surface were increased which lead to an increase in the mixing, turbulence, and heat transfer coefficient. Finally, the slope of ۱۵° has reached the highest heat transfer coefficient with an increase of ۲۰.۰۹% compared to other slopes. Besides the optimized model was mostly overlapped with the experimental results in which Stephan Abdelsalam's model with an average error of ۱۳.۹% and the McNelly model with an average error of ۲۴% had the minimum and maximum amount of error among the other models, respectively.

کلیدواژه ها:

Pool boiling ، Heat transfer coefficient ، Bubble departure frequency ، Bubble departure diameter ، Slope of the surface