Estimation of thermal performance of pv-EFTE cushion roof

Abstract

ETFE (ethylene tetrafluoroethylene) cushion roof integrated amorphous silicon photovoltaic (PV-ETFE cushion roof) is attractive as this roof could provide electricity for maintaining the shape of the ETFE cushion and make the building to be zero-energy. One of the essential factors for this cushion roof is the temperature which affects the system thermal performance. To investigate the temperature and velocity fields inside the PV-ETFE cushion, an experimental mock-up composed of a three-layer ETFE cushion and a-Si PV is developed and experiments for obtaining the temperatures of the cushion roof are carried out under summer sunny conditions. These experimental results could provide the boundary condition for the numerical simulation and for the numerical verification. In this paper, estimation of the temperature field inside the ETFE cushion is performed with the FLUENT and the numerical temperature is compared with the experimental air temperature obtained at the same location. The comparison shows that the maximum difference between the experimental and numerical temperature results is only 3.4 K, which means that the feasibility of the numerical simulation is validated. In detail, for the temperature distribution, it is found that the existence of the PV has a significant effect on the temperature field and that heat transfer mechanisms for the upper and lower chambers formed with the three ETFE layers are the convective and conduction, respectively. For the velocity distribution, the vertical velocity is much greater than the horizontal velocity due to the convective effect.