Constructal Design of a PV cooling System

Leon Fernando Miecoanski¹; Marcelo Risso Errera¹

¹ Universidade Federal do Paraná

doi:10.20906/CPS/CILAMCE2017-0560

Resumo

World energy demand continues to grow while energy and environmental policies point to less dependence on fossil fuels. Thermal solar panels and Photovoltaic (PV) systems have become a viable solution to meet those requirements but they still face efficiency challenges. The high concentrated photovoltaic technology (HCPV) represents an efficient alternative, both in relation to the occupied area and the economic issues. The efficiency of those systems is compromised due to concentration of solar irradiation over the PV-cells. It is then necessary to cool the photovoltaic system in order to avoid structural damage and losses of electrical efficiency. Therefore this work aims to model an active cooling system for HCPV modules and to optimize the design of the micro-channels geometry based on the constructal theory. Better designs are likely to provide the highest electrical efficiency with the lowest operating cost. A multiphysics computational model is developed to solve the equations of continuity (mass, momentum and energy balances) that govern the problem. Water was used as the working fluid, under laminar and turbulent flow regimes. The maximum solar irradiance considered was 1000 W/m². The materials tested for the cooling structure were aluminum, copper and galvanized steel. The amount (volume) of material was held fixed as well as the base area. The aspect ratios of the volume and area were free to vary. External effects such as shading, precipitation and other atmospheric phenomena were disregarded. The performance criteria were the thermal and electrical efficiency, the maximum temperature observed in the panel, the temperature variation in the coolant fluid and the pressure drop of the system. Under the same conditions, the design configuration reached by the constructal design method yielded the highest thermal and electrical efficiency, with equal pumping power. Furthermore, this assembly provided the best temperature distribution between the cells, preventing premature wearing.

Palavras-chave: HCPV system; thermal modeling; constructal design