Flow boiling heat transfer in copper foam fin microchannels with different fin widths using R134a

Heat sinks of copper foam fin microchannels are developed to deal with cooling challenges. The heat sinks consist of fins made of copper foam and channels. The channels are 0.5 mm in width and 1 mm in height, and the fins are 0.5 and 2.0 mm in width. Flow boiling experiments are conducted using R134a at subcooled and saturated inlet conditions. The heat flux is between 22 and 172 W/cm2, and the mass flux ranges from 264 to 1213 kg/(m2 s). The influence of the quality, the heat flux, and the mass flow rate on the heat transfer coefficient is obtained. It is found that wider fin raises the heat transfer coefficient. A correlation is developed based on heat transfer mechanisms, and it predicts the experimental result with a 12% mean absolute error. Compared with a solid fin microchannels heat sink, the heat transfer coefficient of the copper foam fin microchannels is higher (up to 60%) when the heat flux is lower than 100 W/cm2. The copper foam fin microchannels may enhance the heat transfer coefficient and reduce the pressure drop at the same time.