Design, synthesis and nucleate boiling performance assessment of hybrid micro-nano porous surfaces for thermal management of concentrated photovoltaics (CPV)

•Synthesis of new uniform hybrid micro-nano porous surface.•Comparative analysis of nano, micro and hybrid micro-nano surface.•Hybrid surface resulted 2.5 times higher CHF and 2.3 times higher HTC.•Hybrid surface resulted in an enhanced performance for CPV using NBHT. This study investigates the synergistic performance of hybrid micro-nano porous surfaces (HMNP) for Nucleate pool boiling (NBHT) and its application to thermal management of concentrated photovoltaics (CPV). A new set of HMNP surfaces was prepared by two-step method of hot powder compaction of micro-particles followed by nanoparticles coating. Three different surfaces, i.e., plain (P), microporous (MP), and hybrid micro-nano porous (HMNP) were examined for NBHT performance with de-ionized (DI) water as working fluid. In HMNP surfaces three different concentration of nanoparticles 0.0001%, 0.001%, and 0.01% were used for coating. MP showed enhanced HTC and CHF performance, which was further improved by HMNP coating with the highest performance at 0.01% concentration. Compared to P surface, the maximum increase for CHF of MP and HMNP was 1.79 and 2.5 times while the maximum increase in HTC was 1.8 and 2.33 for MP and HMNP surfaces, respectively. For the lowest applied heat flux of 110 kW/m2, the maximum decrease in wall superheat for MP, and HMNP coating was 2.5 °C and 3.7 °C, respectively as compared to the P surface. The increase in CHF and HTC was observed to increase with an increase in the concentration of coated nanoparticles in HMNP surface. Bubble dynamics were observed by the high-speed camera and Scanning Electron Microscope (SEM) analysis, and contact angle analysis were performed for P, MP and HMNP surfaces. In the end, an analytical study is performed to analyze the effect of P, MP and HMNP surface as a resulted enhancement of CPV cell performance.