Abstract: To study the performance of high heat flux cooling devices, a visual experimental setup for flow and heat transfer in manifold microchannels was built. Experiments were conducted to investigate the heat transfer performance of copper-based microchannels. Using deionized water as the coolant, the heat power was varied from 100 to 400 W. The effects of single-phase and boiling flow on heat transfer were analyzed at coolant flow rates of 120 and 300 mL/min. The bubble growth process was also observed. Results showed that under both single-phase and boiling conditions, the thermal resistance decreased slightly as the heat flux increased. During boiling, bubbles formed along the wall, detached from the bottom, and migrated into the manifold channels. When gas had accumulated sufficiently at the inlet of the manifold, it quickly passed through the microchannels below and exited through the outlet channel, enhancing heat transfer performance.

Key words: manifold arrangement, microchannel, single-phase flow, boiling heat transfer, bubble growth