Research On Thermal Characteristics Of Solar Chimney Incorporating With Phase Change Materials

As a sustainable development of natural energy,solar energy has the obvious advantages,such as infinite,universal,clean and economic development,of which full use can effectively reduce building energy consumption.Solar chimney is a typical use of solar passive building structure.With the advantages of high energy storage density,and keeping the temperature constant in energy storage and release process,the phase change materials combined with solar chimney in the summer,can strengthen indoor natural ventilation,and improve the efficiency of solar thermal utilization.In this paper,a three-dimensional geometric model of civil building was established,taking Beijing as the research site,and takin g the meteorological data of typical day as the parameter.CFD was used to simulate and analyze the unsteady state.The effects of channel width,phase change material thickness,phase transition temperature and latent heat on the flow rate and temperature of solar chimney system were analyzedIn this paper,the steady-state simulation of solar chimney structure size,the results show that for 4.8 m × 3.6m × 3m room,120 mm is the best channel width.Compared with the solar chimney system with and without ph ase change materials,it is found that the composite structure of phase change material and solar chimney can avoid the problem of large temperature variation in day and night,and the time of the natural ventilation is prolonged.The influence of the thi ckness of the phase change material plate on the solar chimney system is discussed.From 15 mm to 30 mm,the temperature change between inside and outside of the solar chimney system is smaller with the thickness of the PCM.Finally,the effect of phase chan ge material thermal properties is researched.The results show that the latent heat of phase change materials has little influence on the solar chimney system,and what plays the biggest role is the phase transition temperature.When phase transition tempe rature is small,phase transformation is easy to be created,and it can prolong the natural ventilation time,and the temperature variation range is small.In the air passage,the order of the air temperature is: PCM plate > glass cover plate > air gap.