Effect of Surface Geometry on Pool Boiling Heat Transfer of Water: A Study by ANSYS

Abstract

This study explores the impact of the type of heating surface on heat transfer in pool boiling of water, especially the impact of geometric shape on heat transfer efficiency. Through a numerical simulation using CFD techniques in the ANSYS Fluent program. In this study, a two-dimensional model was built to simulate the pool boiling of water in several cases to compare the impact of the geometric shape of the heating surface. Where the first simulation was implemented using a smooth copper surface with constant heat flux (30????????????2⁄) and then the simulation was repeated several times, changing only the geometric shape of the heating surface without changing the material or dimensions. With the preservation of all parameters of the first simulation, including thermal flux and mesh settings, to maintain the accuracy of the results and obtain a correct comparison. Where the first simulation was amended by the geometrical shape of the heating surface by providing it with different geometric shapes (semicircular, square, trapezoidal), with the preservation of the groove area in the three cases. By comparing the results of different shapes and extracted from ANSYS (heat transfer coefficient, overall heat transfer performance, thermal resistance and Nusselt number), it shows that semicircular grooves increase heat transfer coefficient (HTC) by 42.1%, overall heat transfer performance by 42% and Nusselt number by 35%, and decrease the thermal resistance by 42.4% compared to smooth surface. The heating surface with square grooves increase heat transfer coefficient (HTC) by 66.24%, overall heat transfer performance by 65% and Nusselt number by 50.2%, and decrease the thermal resistance by 66.3% compared to a smooth surface. The heating surface with trapezoidal grooves increases heat transfer coefficient (HTC) by 96.92%, overall heat transfer performance by 95% and Nusselt number by 90.62%, and decrease the thermal resistance by 96.7% compared to a smooth surface.
Therefore, by comparing the results of each geometric shape of the heating surface in each case to the smooth surface, and then compare the results of these different shapes with each other, it was concluded that the best geometric shape of the grooves was a trapezoidal geometry. Which achieves the highest value of heat transfer coefficient (HTC), overall heat transfer performance and Nusselt number, and the lowest value of thermal resistance between the difference in geometric shapes of grooves.