Enhancement heat transfer rate per unit volume of microchannel heat exchanger by using a novel multi-nozzle structure on cool side

In the present work, a novel multi-nozzle microchannel heat exchanger (MN-MCHX) was proposed. The effects of the channel depth ratio, channel length ratio, inlet temperature of the hot fluid, and pumping power on thermodynamic properties of the MN-MCHXs were numerically investigated in detail. A copper plate of 10 mm × 10 mm × 0.9 mm was considered as a fixed substrate, and water was used as working fluids. For all cases in this study, a maximum thermodynamic performance index, ξ, of 9.5 W/kPa was achieved by a locally optimal MN-MCHX at a pumping power of 0.1 W, and this maximum ξ was improved up to 124% compared to that of an original MCHX. Furthermore, a maximum heat transfer rate per unit volume of 14216.89 MW/m3 was also achieved by the locally optimal MN-MCHX at a cold-side Reynolds number of 435. It was found that the novel MN-MCHX not only could remarkably enhance the heat transfer rate, but also could remarkably reduce the total pressure drop. The MN-MCHX is a promising structure because its thermodynamic performance index can be improved by optimizing geometric dimensions.