Numerical Simulation Of Thermal Performance Of Solar Air Collector In Winter

As a clean and resourceful energy source, solar energy is paid more attention and widely applied in many arena, such as heating air-conditioning and drying etc.. And solar collection module that combines solar collector system and air-blasting system own extensive development space in the way of structural heating by reason of its facility and high effect.Solar collection module studied in this paper is composed of solar collection component, air-blasting component and frame. The solar collection component is a aluminium Venetian blind two facades painted with two different colors in the purpose to receive the incident radiation energy using the dark side during winter period while reflect the radiation using the light side in the summer. Numerical simulation method is used in this study and a commercial CFD software FLUENT have taken to simulate the thermal collection process of the module. There are thermal collection and exchange between transparent cover plate and outdoor environment, thermal collection of blind, thermal loss of frame, convection thermal exchange between blind and air in gap. A predigested calculating model is adopted in this paper and the first three parts of thermal process has been solved by theoretical analysis method and input into calculation model as boundary conditions. Complex thermal exchange in collector module is mumerical simulated in calculation model. Beacause of the characteristics, such as the big difference between the area of wind pipe and collector, complex structure of blind, a three-dimension model has been built and simplified by substitution of a porous model for blind model. By using method of changing parameter of calculation model, the advantages and disadvantages of collector module has been analyzed from the heat removal factor and heat loss coefficient perspective. Research shows that: (1) Thermal efficiency will invariant if air mass flow rate in collector module, so the shape of tuyere could be chosen according to the request of velocity of indoor supply airflow. (2) Thermal efficiency of collector module could be improved by widening gap, but too wide gap will increase cost and be not relative to the elevation of thermal efficiency. For the module in this paper, 80mm width gap is recommended. (3) From the angle of flowing in module, imperforated plate collector is much better and outside in-wind mode is better than outside in-wind model. (4) With the increasing of inlet airflow velocity, heat removal factor is increased, but the heat loss efficiency is increased too. A biggish inlet airflow velocity could be used in a region which is rich in solar resource. For the application in Dalian region, 1m/s is recommended. The influence weight of heat removal factor to thermal efficiency of module is less than the heat loss coefficient.