Numerical and experimental approach for evaluation of thermal performances of a polymer solar collector

This paper presents a novel 2D numerical and experimental approach which can be used to assess the thermal performances of a polymer solar collector as a part of the design process. Numerical simulations are performed using software package FLUENT. To simulate radiative heat transfer, different radiation models that are available within FLUENT are applied including the discrete ordinates (DO) and surface-to-surface (S2S) model. Solar incident radiation is taken into account as an energy source computed analytically or via ray tracing software or as an external beam which is a part of boundary condition in semi-transparent DO model. Different combinations of longwave and shortwave radiation modeling are tested, first on a segment of a typical flat plate collector. In the second step, these models are applied to the test box at different boundary conditions and materials. Numerical models are then applied to the geometry of polymer solar collector prototype to assess its thermal efficiency. Combination of longwave radiation computed with DO and S2S sub-model and solar incident radiation modeled analytically or via ray tracing software yields sufficiently accurate results on the all tested computational domains, thus any of them can be used to compute thermal efficiency of a polymer solar collector. On the other hand, when applying semi-transparent DO model with the solar incident radiation modeled by the external beam, the obtained results are unphysical. Present approach is a part of the research aimed at the development of a thermally efficient low-cost polymer solar collector running in a drain back system. The prototype will be then experimentally tested.