Conjugate fluid-solid heat transfer in a pin-fin microchannel heat sink is an effective way to dissipate heat from the heating surface with high heat flux. The introduction of fins increases the heat exchange area and enhances flow turbulence, while it increases the flow resistance at the mean time. The thermal-hydraulic performance of heat sink is affected by fin shape, density and flow parameters. In this paper, contrived numerical simulations of the flow and heat transfer process in elliptical pin-fin microchannel heat sink are carried out, including 2033 cases with different fin sizes, numbers and flow velocities. The simulation results show that the flow velocity and fin transverse width are the main factors affecting heat transfer and fluid flow. Three artificial neural networks are established to predict the average tem-perature, the temperature non-uniformity of heating surface and the pressure drop of microchannel. The predicted results show that the pump power and heating surface temperature are contradictory objec-tives. A microchannel with the optimal thermal-hydraulic performance is selected. It has numerous fins which are longer in the flow direction. The empirical correlations for Nusselt number and friction coeffi-cient of the optimal microchannel are proposed.(c) 2023 Elsevier Ltd. All rights reserved.

The collection and reuse of thermal radiation energy generated by high-temperature objects has always been the focus of attention and research. Here we designed and fabricated a compound parabolic concentrator (CPC) that can be used for infrared radiation energy collection based on non-imaging optical technology. The energy gathered by CPC has a significant effect on the improvement of the surface temperature of objects. The thermoelectric (TE) generator is a good choice to utilize this thermal energy. This paper analyses and discusses the effects of CPC on the performance of thermoelectric model by simulation. The result has well demonstrated that the TE model with CPC has not only a considerable reduction in structure size and material consumption, but also ensures higher output power and efficiency. In addition, we propose that the array of CPC shall prominently enhance the performance of thermoelectric device.