Mathematical modeling investigation on flow boiling and high efficiency heat dissipation of two rectangular radial microchannel heat exchangers

To solve the heat dissipation problem of high heat flux devices, flow boiling heat transfer in microchannels is widely used and investigated. Two types of rectangular radial microchannel heat exchangers, without and with grooves, were experimentally studied and reported by us. To further improve their heat transfer performances by optimizing their structural parameters, two mathematical models are developed, with heat transfer coefficient (HTC) used as validation parameter. As analyzed, for two rectangular radial microchannel heat exchangers, without and with grooves, the average deviations are 3.62% and 7.03%, respectively. The modeling results show that, compared with the heat exchanger without grooves, the one with grooves always has better heat transfer performance. For two microchannel heat exchangers, without and with grooves, the influence of adjusting structure parameters on the HTC is obvious, and the maximum changes of HTC reaches 32.56 kW/m²K and 70.33 kW/m²K, respectively. Under a heating load of 400 W and a volume flow rate of 8 L/h, the heat transfer performance of heat exchanger without grooves could not be improved. While under the same conditions, the predicted HTC of the heat exchanger with grooves is improved to 102.56 kW/m²K, which is 58.69% higher than the experimental data. The results of this study are expected to provide references for the structural design optimization of microchannel heat exchangers.