Heat transfer augmentation in a heating surface covered by variable-shape or double-layer porous media subjected to water jet impingement

Abstract

In this study, a cooling scheme for high-power and highly-integrated electronic devices is proposed in which the heating wall is covered with a variable-shape or double-layer porous medium. The porous media impacted by water jet impinging is covered over the heating surface, wherein heat from bottom wall to porous matrix is transmitted by thermal conduction and dissipated by convection generated by water jet impinging in porous layer. A combination of Brinkman–Darcy–Forchheimer model with energy equations in local thermal equilibrium is employed to describe the hydrothermal transport details in porous matrix, and the k-ε model is used to interpret water jet impinging. The impacts of porous shapes, porosity distributions, and thickness ratios among lower and upper layers with various porosities in gradient variation configuration on heat dissipation capacity are investigated numerically. The numerical calculations are well verified by published experiments. Results show that rectangular porous media covered heating surface is more sensitive to changes in jet velocity, while the mode with triangular porous media results in lower surface temperature and higher heat transfer coefficient at stagnation point. Besides, the rise ratio of heat transfer coefficient of porous configuration with gradient increase in porosity from 0.6 to 0.8 is 11.84% higher than that with gradient decrease in porosity from 0.9 to 0.6. Finally, the optimized shape, porosity arrangement and thickness ratio, jointly affect the heat transport. The results obtained can be used to generalize and apply the coupling of jet impingement with porous media above the heating surface to augment heat transfer.