Research On Thermal Characteristics Of Selectivesolar Tunnel Wall In Winter Working Condition

At present, with the aggravation of the energy crisis and the proportion of building energy consumption in energy consumption structure increasing, persistent efforts of building energy saving is of great significance.Selective Solar Tunnel(SST) technique can absorb the solar radiation according to the different solar angle so as to heat the house in winter and avoid heating in summer.It is a promising solar thermal utilization technology.In this paper, experimental research and numerical simulation were used to study the thermal characteristics of SST wall in winter working conditions.A soalr house with SST wall was built and the thermal characteristics of SST wall in typical winter day are tested and analyzed.The research shows that:The temperature of absorber plate fluctuates around a temperature on the whole while slightly upward or downward locally in horizontal direction;The temperature drops in vertical direction,and the difference is small in up part and relatively large in middle and down part.In sunny days SST wall can meet the heating requirements of the house alone;In cloudy days;SST wall will causes additional heat loss to the outside,and other equipment for heating is needed, and ventilation holes should be closed.Through analysis and reasonable hypothesis, a reliable numerical model of thermal characteristics of SST wall is built and some important factors are studied. The research shows that: Temperature of each part of the absorber plate, outlet air temperature and heat flux density increases direct linearly with the increase of solar radiation intensity;The above parameters gradually decreased with the increase of outdoor wind speed and gradually increased with the increase of environmental temperature;Temperature of each part of the absorber plate and outlet air temperature decreased with the increase of the inlet velocity while the heat flux rise straightly.The calculating formula of SST wall heat loss is obtained through the results of numerical calculation, using multiple nonlinear regression, which laid the foundation for the designing and engineering application of SST wall in the future.