Numerical analysis of the Al2O3-water nanofluid forced laminar convection in an asymmetric heated channel for application in flat plate PV/T collector

摘要

The present paper proposes an investigation on the application of Al2O3-water nanofluid within a PV/T panel in order to assess the potential to improve the performance of the device. The analysis has been carried out by developing a numerical model by means of the commercial software Comsol. Two dimensional nanofluids laminar convection flows for Re comprised between 250 and 1000, concentration between 0% and 6%, inlet temperatures of 293.15 K and 323 K and particles dimension of 20 and 40 nm have been simulated in an asymmetric heated channel. Under an imposed external heat flux of 1000 W on the top surface of the channel, the results show that nanofluids guarantee better cooling performances, in fact a decrease in top wall temperature of similar to 3 K is observed for an inlet temperature of 293.15 K and a reduction of similar to 5 K is observed for an inlet temperature of 323 K. Nusselt number and average heat transfer coefficient for nanofluids also increase in a range between 2% and 15%. On the contrary, a relevant increase of pressure drops is detected. The combined effect of heat transfer enhancement and pressure drop increase has been investigated by implementing an entropy generation analysis, which highlights that reduction of thermal entropy generation is more significant than the increase of frictional entropy generation. (C) 2017 Elsevier Ltd. All rights reserved.