Enhancement of concentrator photovoltaic system through convergent-divergent microchannels

Abstract

Concentrated photovoltaic technology is one of the evolving technologies that converts solar to electrical energy with a high efficiency percentage. Increasing concentrated photovoltaic cell’s temperature significantly reduces the performance of the system. Thus, in order to properly functioning of system, thermal management will be a rudimentary issue. This article focuses on the cooling performance of high-concentration photovoltaic system using microchannels attached to the bottom plate of solar cell. To this end, the effect of convergent-divergent microchannels at three amplitudes and three wave lengths at different Reynolds numbers is investigated, and results are compared with simple microchannels. The output results are presented via temperature, pressure, velocity contours as well as Nusselt number, friction factor, and effectiveness ratio. Compared to the simple microchannels, convergent-divergent microchannel lowers the wall temperature about 0.4–2 Kelvin by making velocity gradients along the channel. This leads to boosting the heat transfer capability up to 3 times in the best case and up to 1.5 times in the worst case. Increasing the wave length enhances the performance of system, while the opposite trend has been seen for greater wave amplitudes. For case A with lowest wave length, Nu increases 1.92 and 2.4 times at lowest and highest Re numbers while friction factor increases due to the higher contact surface area along the fluid stream. Moreover, increasing the wave amplitude leads to higher Nu number, higher friction factor and consequently lower effectiveness ratio. Finally, effectiveness ratio as a criterion to choose best case has shown that a higher wave length alongside with lower wave amplitude offers better heat transfer enhancement and lower pressure drop compared to simple channel. Case C-1 as a best case offers 0.8K lower wall temperature, 1.6 times better Nu number with only 1.3-time higher friction factor.