Hydraulic and thermal engineering calculation in the laminar mode of operation of a photoelectric thermal battery

Abstract

Efficient conversion of solar energy into electrical and thermal energy has become a major goal of researchers around the world. In this regard, the authors have developed photovoltaic thermal installations to efficiently convert solar energy into electricity and heat. This article briefly analyses the development of a photovoltaic thermal system for efficient cooling of the photovoltaic part with various methods and coolants. A photovoltaic thermal battery (PTB) with a cooling system based on multichannel polycarbonate has been developed. The dimensions of the cellular polycarbonate channels are 7 x 12 mm2. Water flows horizontally through more than 200 channels in parallel streams. The thickness of the cellular polycarbonate sheet is 4 mm.The PTB cooling system is a structure consisting of a sheet of cellular polycarbonate and channelopenings, which are attached to two perpendicularly located polypropylene tubes using transparent siliconesealant. This design of the cooling system (absorber) has less weight and a lower cost compared to traditionalmetal structures, and the cellular polycarbonate sheet in the PTB is protected from direct exposure toultraviolet radiation emitted by the sun. The model of a combined PTB installation based on a "photovoltaicbattery and heat converter" (PVB-TC) was implemented using COMSOL Multiphysics 5.6. Hydraulic andthermal calculations were carried out in laminar mode, and PTB parameters were determined: watertemperature at the outlet of the absorber PTB 𝑡2, water pressure at the inlet of the absorber 𝑡1, and water flowG at the corresponding water velocities W=0.1 m/s, 0.2 m/s, and 0.3 m/s, taking into account three values of ambient temperature - 25 °C, 35 °C, and 45 °C. The modelling process took into account the use of concentrated solar radiation in a combined PEP-TEP installation using weakly concentrating reflectors.