AN EXPERIMENTAL STUDY TO IMPROVE HEAT TRANSFER IN HEAT SINKS WITH STRAIGHT CHANNELS AND CHANNELS WITH SYMMETRICAL CIRCULAR CAVITIES

ABSTRACT: In this research, an experiment was conducted on two types of channels: straight channels and channels with symmetrical circular cavities. They were compared and the thermal performance of the heat sinks in boiling conditions was found out. The selected indicators were: average wall temperature, outlet temperature, and thermal resistance. The three indicators were studied with respect to the effects of the heat flux and Reynolds number. The flow patterns were captured during boiling to understand the physical changes that occur at the boiling process. The results demonstrated that the heat transfer was increased by 12% in the channel containing the symmetrical circular cavities in comparison to the straight channel. This design resulted in a lower outlet temperature in the channel and lowered average wall temperature. Drying process was also delayed reducing the thermal resistance, and localized fluid recirculation was observed. The flow patterns illustrated indicated that at high heat fluxes, up to 500 kW/m² the straight channels had significant drying and the channels containing circular cavities had favorable drying. Symmetrical channels continued to be hydrated and boiling was fairly stable. From all the results it can be concluded that the channel which has symmetrical circular cavities is the best channel for cooling applications in electronic devices subjected to high heat flow.