Experimental Study on the Effect of Microchannel Spacing and Fractal Angle on Bubble Growth Behavior

Abstract

Bubble growth behavior significantly influences boiling heat transfer performance, and different microchannel structures and configurations affect bubble growth behavior. To explore the impact of microchannel structures and configurations on the growth behavior of boiling bubbles, two types of microchannel test plates were fabricated on copper substrates using laser machining technology. It was a parallel configuration plate with five different microchannel spacings and a blade vein configuration plate with four different fractal angles. The bubble growth behavior on these two types of surfaces was studied through visual experiments. The results show that smaller microchannel spacing leads to earlier bubble coalescence and departure times under the same degree of superheat. The 3.00 mm microchannel spacing is the critical interfering distance for the parallel configuration plates, while interference behavior occurs for the bubbles on the simulated vein configuration plates at any fractal angle. Furthermore, in different ranges of superheat, the bubble departure diameter increases with increasing superheat, and the frequency of bubble departure initially increases and then decreases with increasing superheat. This study provides experimental data support and design reference for the design of heat transfer plate structures.