Markedly enhanced pool boiling heat transfer performance on maicropaorous copper surfaces fabricated utilizing a facile wire cutting process

Abstract

The superior boiling surfaces obtained by facile, efficient and economical approaches are highly desirable in large-scale industrial applications. Here, a microporous copper surface for enhanced boiling was readily and rapidly prepared by utilizing a single-step and low-cost wire cutting electric discharge machining process. The saturated pool boiling tests on the microporous and plain copper surfaces were conducted at atmospheric pressure using distilled water as working fluid. The significant boiling performance enhancements are demonstrated on the microporous copper surface. It achieves a heat transfer coefficient (HTC) of 16.7 W cm−2 K−1, a critical heat flux (CHF) of 185.7 W cm−2 and a onset of nucleate boiling (ONB) at 4.4 K, indicating a 198% higher HTC, a 61% higher CHF, as well as a 47% lower ONB compared with the plain surface. The enhanced boiling mechanism is explained based on the surface characteristics. The formation of numerous microscale cavities facilitates bubble nucleation, departure for reducing ONB and increasing HTC, and improves surface wettability for delaying CHF. The visualization investigations of bubble behaviors were also conducted for further verifying our analysis. The results show the microporous copper surface exhibits a larger nucleation density, departure frequency, and a smaller departure diameter of bubble.