Hydrothermal, entropy generation and exergy performances analysis in a mini-channel with combination of longitudinal and transverse vortex generators using Al2O3 nanofluids

With high-tech industrial development, micro/mini-channel heat sinks (MCHSs) are very widely applied for heat dissipation in high-heat-flux devices in these industries. At present, the energy crisis and environmental problems have been restricting human development. Therefore, MCHSs with low energy consumption are urgently designed. In this investigation, a new MCHS with a combined structure of longitudinal and transverse vortex generators is designed and the Al2O3 nanofluid is used as a working medium to further improve various performances of this MCHS. The effects of the transverse vortex generator shape and longitudinal vortex generator angle on the hydraulic characteristic, thermal characteristic, comprehensive performance, entropy generation and exergy efficiency are explored. It is found that the triangular transverse vortex generator is conductive to improve the comprehensive performance and exergy efficiency. Whose performance evaluation criterion is 22.34% on average higher than that of the smooth mini-channel, and the average exergy efficiency reaches 94.30%. On the basis of this, combining the longitudinal and transverse vortex generators can further improve the various performances in mini-channel. The optimal combined structure is the combination of triangular transverse vortex generator and 90°-longitudinal vortex generator and can make mini-channel yield the best comprehensive performance, entropy generation and exergy efficiency. Which obtains the highest performance evaluation criterion (1.36) and exergy efficiency (97.63%) when Reynolds number is 742. Overall, the new MCHS performs a beneficial effect on comprehensive performance improvement in mini-channel to enhance energy efficiency.