Flow boiling heat transfer of water in microchannel heat sink

The flow boiling heat transfer of water in a microchannel heat sink with variable initial vapor quality at the inlet is investigated. The stainless steel microchannel heat sink contains ten 640 × 2050 μm channels with a length of 120 mm; the wall roughness is 10 μm. The data on the local heat-transfer coefficient distribution in heat sink length are obtained in the range of mass fluxes from 30 to 90 kg/m²s, heat fluxes from 40 to 170 kW/m², and vapor qualities from 0 to 1. The heat transfer instability associated with dry spots resulting from insufficient wetting of channel walls introduces substantial contribution to the heat transfer mechanism and leads to decreasing heat transfer in heat sink length downward the flow. The developed method for calculating the flow boiling heat transfer of water in a microchannel heat sink allows more accurate prediction of heat transfer drop than available methods.