Experimental investigation of a new hybrid structured surface for subcooled flow boiling heat transfer enhancement

Abstract

A new scheme with hybrid submillimetre/micro/nano-structured surfaces providing both high subcooled flow boiling performance and relatively low flow resistance was proposed to develop highly efficient and reliable water cooling schemes for plasma facing components (PFCs) in future nuclear fusion engineering. Both comparative microscopic surface structure pattern observations and macroscopic mockup subcooled flow boiling experiments under fusion reactor like heat flux conditions were conducted. The proposed technique can create hybrid structures favourable for subcooled flow boiling enhancement: including increasing bubble generation sites and multiscale instability etc. We demonstrated that the heat transfer coefficients of manipulated surfaces in the subcooled flow boiling state were almost doubled and that the critical heat flux (CHF) values were promoted by 80–200% under the tested flow conditions compared with under smooth surface conditions, with the flow path pressure drop deteriorating by less than 12%, indicating better capacities of high heat flux removal and low flow path resistance than those of existing PFC cooling schemes. The results encourage further optimization and development of this new scheme for practical application in nuclear fusion engineering.