Nature of substrate modification effect on thermal performance of simulated solar cells over phase-change immersion cooling under high concentration ratios

Abstract A new point from modifying substrate structure of solar cells is proposed based on direct-contact phase-change immersion cooling to solve the heat dissipation problem of solar cells worked under high concentration ratios. An electric heating plate (EHP) is carefully designed to simulate the heat flux of solar cells under high concentration ratios (184.2 X). Easy and lower cost ways of electrochemical etching and mechanical drawing bench are adopted to modify substrate surface of simulated solar cells. The result of thermal measurement shows substrate, undergoing electrochemical etching for 2 h (CE-2) or mechanical drawing bench using 800 mesh (MDB-800), owns the lower wall average temperature (85.36 and 85.7 °C) and higher surface heat transfer coefficient (3008 and 2970 W/(m 2  K)). SEM results reveal that CE-2 or MDB-800 has uniform-distributed porous or dense-grooved structure. These special structures show better surface wettability and provide more active nucleus sites for small bubbles generation as well as higher bubbles update frequency according to our modified surface wettability and quantitative analysis results. Our study reveals that the advanced heat transfer performance is attributed to substrate structure with uniform-distributed porous or dense-grooved of CE-2 or MDB-800. This work gives a theoretical guidance for heat transfer advancement investigation involved in surface characteristic.