Numerical performance investigation of a photovoltaic-thermal hybrid collector-evaporator with different tube configurations for heat pumps

Abstract

Surface temperature build-up due to the continuous conversion of incident sunlight to heat deteriorates the power output, efficiency, and life of photovoltaic panels. Photovoltaic-thermal (PV-T) systems provide a potential solution to avoid excessive heating of PV panels, simultaneously providing useful heat energy. A heat extraction unit is attached to the PV panel in PV-T systems that extract and convert the waste heat into useful heat. Therefore, design and material selection are keys to better performance in the system-level approach. Additionally, it is a cumbersome task dealing with refrigerant-based heat and fluid flow interactions in a system-level approach. With this in perspective, this paper analyzes different materials and flow configurations of PV-T systems. A transient, three-dimensional turbulence solver coupled with heat transfer through solids and liquids physics is modeled using COMSOL Multiphysics software. R-32 refrigerant acts as the heat transfer fluid in the system loop. The conservation equations are discretized using the finite element method. The present study involves two different plate materials (aluminum and copper) and three flow configurations (serpentine, roll-bond, and spiral) with and without absorber plates. A total of eight different configurations are being investigated here. The obtained results suggest that with the absorber plate, the performance increases significantly with a PV panel temperature decrease of 4–5 K, and the outlet fluid temperature increase by 2–8 K. It was observed that the performance difference between copper and aluminum plate is minimal (2%). Roll-bond flow configuration has scope for further research since it is more efficient than others because of the larger contact area for heat transfer.