Experimental Investigation of Saturated Flow Boiling Characteristics in Micro Pin Fin and Micro Cavitied Heat Sinks

Flow boiling in microchannels is a popular thermal management technique with the potential to provide cooling solutions required for sustainability and safe operating conditions in systems where high-density waste heat is released, such as high-capacity electronic systems in aircrafts, processors of computers, and batteries of electric vehicles. In the present paper, saturated flow boiling of deionized water in a heat sink having gradually expanding flow passage and artificial nucleation sites (modified heat sink, MIA) was experimentally investigated at different mass (136 and 250 kg m(-2) s(-1)) and heat flux (132 272 kW m(-2)) values. Results were comparatively presented via plain wall parallel microchannel heat sink (conventional heat sink, KIA). Inlet temperature of working fluid is kept constant at nearly 75 degrees C. Flow images were taken via high-speed camera (1000 fps), and the physical mechanism was scrutinized by supporting with the images. Compared to KIA, in the MIA, an improvement in two-phase heat transfer coefficient up to 827.2% is obtained, and flow boiling instabilities could be successfully suppressed. Contrary to enhancement in heat transfer, an increase up to 50.5% occurred for pressure drop. As general character, for both the heat sinks, effect of mass flux on pressure drop is relatively negligible, and heat transfer coefficients decrease with increasing mass flux. Compared to KIA, results of MIA are relatively more influenced from variation in mass flux.