ИСТИНА

The problem of overheating of solar cells on a moving vehicle and its possible solution using forced convection associated with the vehicle motion have been investigated by means of CFD simulation and experimental analysis. It can be summarized that convective cooling is efficient enough for small-sized models even at relatively low velocity. For a full-sized solar car the heat transfer coefficient is smaller, so larger velocity has to be maintained to avoid overheating. The most problematic is the stagnation region after the flow separation. Designing aerodynamically efficient shape of solar car roof to avoid flow separation or properly shunting the solar cells in this region or even removing them might improve the performance of the entire system. Both experimental data and theoretical analysis demonstrate that one-layer thermal model of solar cell is valid except for the case of very high convective heat transfer coefficient at high velocities or for very small objects. Approximate relations for effective heat transfer coefficient based on boundary layer theory were shown to yield reasonable accuracy but accounting for radiative heat loss is essential for achieving better agreement. These relations also fail to describe heat losses at low velocities when natural convection plays an important role and (if heating is large) flow structure can be modified by buoyancy and turbulence amplification due to heating. Developing more accurate approximate formulae for arbitrary aerodynamical shape is desired because numerical simulations are computationally costly due to large typical time of the process.