Numerical Research On The Heat Transfer Process Of The Unglazed Solar Wall

In the process of development of solar architecture, the way how to integrate the solar air heating devices into the building is a problem. The porous transpired plate solar wall is an effective way to those problems. By the CFD technology, this paper studied numerically this solar air heating device in two perspectives: the local convection of plate and the flow of the whole solar wall. And make field synergy analysis for local representative area of the porous collector plate.Through the numerical simulation and field synergy analysis, we found that not only viscous drag loss, but also the inertia losses existed in the air flow over the plate. Because the fields of temperature and velocity are more synergical in the area of the outer surface of the plate, more energy exchange would take place in here. The transpired velocity is the main factor affecting performance of the collector, and pore pitch and diameter has less effect compared with velocity. For specific collator, the efficiency of heat exchange is only ralated to Reynolds, porosity, and the relative thickness, not influenced by solar radiation and outdoor air temperature. Compared to conventional soalr collector plate, the field synergy of the air flowing over the porous transpired collector plate is better.The paper also established a porous media model which is suit for porous transpired solar wall, and introduced effection of wind in the form of wind pressure. Through numerical calculation, we found that the local transpired velocity is less than the average pumping speed in the top and bottom of the surface of the plate, but for the low condition, there is not the flowback phenomenon happens. With the pumping speed increased, the influence of the wind becomes smaller, and the distribution of the surface temperature and transpired velocity are more uniform. But the thinner of the cavity, the surface temperature and transpired velocity are more uneven.