Enhancement of the cooling capability of a high concentration photovoltaic system using microchannels with forward triangular ribs on sidewalls

Abstract

Numerical simulations were performed to investigate a microchannel heat sink device as cooling option for a high concentration photovoltaic system. COMSOL Multiphysics 5.1 software is used to solve three-dimensional equations which consider conjugate heat transfer, viscous dissipations, and temperature-dependent-properties. This study investigates the integration of microchannels with complex geometric features on its inner walls into the solar cell structure, to enhance the heat transfer performance of a microchannel heat sink-based active cooling system. Inner sidewall mounted forward triangular ribs are considered in aligned and offset distributions along the microchannel walls. In addition, numerical analysis is developed for a conventional flat plate heat sink integrated to a high concentration photovoltaic system to stablish a baseline solar cell temperature. The numerical results show that a micro-channel heat sink device can control and keep in very low range the solar cell temperature ( 200. At Re = 400, the pumping power reaches 41% and 23% of the total power generated by a multi-junction solar cell in the aligned and offset rib distribution, respectively. The pumping power is greatly reduced while using smooth microchannel, because the maximum pumping power is only 9.5% of the solar cell power at Re = 400, however, the resulting solar cell temperature is slightly higher compared to microchannels with aligned and offset rib configurations. A microchannel heat sink provides a more effective cooling solution compared to a passive flat plate heat sink for a high concentration photovoltaic system. In addition, the possibility of direct integration of a microchannel heat sink into a solar cell structure as proposed in this study, represents an interesting option to feasibly increase thermal performance to a considerable level by maintaining the solar cell temperature in a very low range.