Modelling of natural convection in vertical and tilted photovoltaic applications

This investigation aims to examine and infer useful engineering information of the physical mechanisms which are found in applications of building-integrated photovoltaic (BIPV) systems for façades and roofs. Buoyancy-driven flow in heated open-ended channels was modelled with the channel inclination angle ranging from 15° to 90° and the channel height-to-width ratio being 20. In each case, a uniform heat flux was applied along the top wall and the bottom wall was assumed to be adiabatic. Effect of varying inclination angle on the velocity and temperature fields is explored through the mean and turbulence quantities. A comparison between experimental and modelling results shows that open-ended channels with low inclination angles are characterised by low chimney effect and induced flow rate, thereby decreasing the heat transfer along the photovoltaic panels. In addition, propagation of disturbances and vortical structures in the channel which are necessary to enhance heat transfer are less eminent in these cases. Furthermore, heat transfer characteristics of turbulent natural convection in tilted channels are recast in terms of relevant dimensionless parameters so that they may be readily applied in cases with the aspect ratio and heat fluxes which are considered in this study.