Boiling enhancement on the thermally induced deformation surfaces

Abstract

Enhancing boiling heat transfer by adding microstructures to boiling surfaces is an effective and simple method. However, traditional heat transfer surfaces cannot change their geometric structure after processing and forming and can only have good heat transfer characteristics under certain heat transfer conditions. Shape memory alloys exhibit a wide range of transformation temperatures and superior mechanical properties, which are expected to achieve adaptively enhanced heat transfer. In this study, the pool boiling heat transfer performance of surfaces with different structures made of shape memory alloys using HFE-7100 as the working fluid has been studied. The experimental results indicate that the curved microstructures have more activated nucleation sites, which are conducive to bubble generation in the early stage of boiling but prevent bubble detachment and liquid replenishment in the later stage of boiling. In contrast, the onset of nucleate boiling (ONB) of the upright microstructures appears later, and there is "boiling retardation", but it has higher heat transfer coefficients (HTCs) and the critical heat flux (CHF) in the later stage of boiling. However, the deformable microstructures surface (DMS) can adaptively adjust its microstructures to meet the heat transfer requirements at different boiling stages. Consequently, the DMS has the highest CHF and HTC, with maximum improvements of 98.58 % and 104.88 % compared to the polished surface (PS), respectively.