A Theoretical Analysis And Numerical Simulation On Solar Chimney Power Plant System With Vercical Collector

In recent years, the exhaustion of non-renewable energy and environment pollution bring many troubles and we need to find new resources urgently to replace traditional fossil energy. To solve the energy crisis and environmental problem and to realize the sustainable development of economy and society, we should use renewable clean energy on a large scale. In all renewable clean resources, solar energy is considered as the promising alternative energy in the future by international experts.The main uses of solar energy can be divided photoelectricity and thermal utilization. Solar chimney power plant system is a kind of light-heat-electricity conversion technology based on thermodynamic cycle, which is a promising indirect electricity generation technology. Traditional solar chimney power plant system can only be set up on the desertification area with abundant solar resources but is not suitable for cities. This paper designs a new kind of solar chimney power plant system with vertical heat collector which can be applied in cities.According to air flow mechanism, the ideal and actual thermodynamic cycles are established. The cycle process of the solar chimney power plant system with vertical heat collector is essentially thermo motor cycle. In theoretical analysis, the formulas of ventilation, maximum power and maximum conversion efficiency are obtained considering influences of heat and wind pressure. The influences of solar radiation, the height and width of heat collector on ventilation, maximum power and maximum conversion efficiency are analyzed through MATLAB programming method.Based on the theoretical analysis, the numerical simulation is used and the results shows that: the ventilation and maximum power increase with the increase of solar radiation but solar radiation has a little effect on maximum conversion efficiency. The height of heat collector is the key influence factor to system operation and the ventilation and maximum power increase with its increase, it is also the main influence factor to maximum conversion efficiency. With the increase of heat collector width, the maximum energy conversion efficiency is almost constant, the ventilation and power of the system increase but the increasing value reduces gradually. This is because the change of heat collector width influences heat-exchange performance in transition region. When the width increases to a certain value, the heat transfer of the air flow has fully developed. The ventilation reaches to maximum value when the ratio of height to width is 15～20. With the increase of air layer thickness, the ventilation increases first and then decreases. Considering the system is installed on the south wall of high buildings, the thickness should not be too big in order not to affect the construction appearance. This paper argues that the reasonable thickness is 0.2～0.5 m.Because in the theoretical analysis, backflow phenomena, the energy loss of air flow, wall friction loss and the energy dissipation of turbulence are not considered, theoretical analysis results are found significantly greater than numerical simulation results.The numerical simulation results are verified through orthogonal test method. The result shows that the heat collector height is the most critical factor to influence the ventilation, the maximum power and the maximum energy conversion efficiency of the system.