Research On The Performance Of Solar Chimney For Heating In Winter

With the steady growth of the economy,more and more people pay a attention to the problem of energy and environment. Solar energy is very popular with people which is a new and energy saving type of renewable energy. If we can use the solar energy effectively and efficiently in the field of HVAC, the energy consumption of building will be decreased at some degree. At present, the solar energy is mainly used in heating, ventilation, air conditioning, refrigeration, et al in HAVC.Solar chimney is one of the solar energy utilization technology which has the advantages of reducing energy consumption of building and improving the air quality of room, which is used in the design of the ecological architecture and the green building.This paper introduces the principle and the process of the solar chimney in two kinds of the operating conditions-in summer and in winter and focuses on the analysis of the characteristics and the performance of two kinds of the operation modes of solar chimney in winter. The two kinds of operating mode were studied by theoretical analysis and calculation. The relationships between air flow rate with the chimney width 、 height 、 solar radiation 、 the area of inlet and outlet and the indoor/ambient temperature were obtained.(1)When α=0.95,τ = 0.85,the area of inlet and outlet is 0.1m2,0.1m2,chimney height is 1~4m, chimney width is 1~4m, the intensity of solar radiation is200~400W/m2, results indicated that the air flow rate increases with solar radiation and chimney height、width and reaches its maximum under the calculation conditions when the area of inlet/outlet equals 0.3m.When the height and width of solar chimney is 3m, 1m, the length,width and height of room are 3m, 3m, 3m, with open-type all fresh air system the inlet height and outlet height of the chimney is 0.1m,0.1m,respectively. With close-type indoor air circulation system, the inlet height and outlet height of the chimney is 0.1m,0.1m, respectively.(2)When the height of solar chimney is 3m, the width of solar chimney is 1m,the depth is 0.1m, the size of the inlet is 1m×0.1m, the size of outlet is 1m×0.1m, the calculation of the above two kinds of heating modes in Lhasa, Wuhan and Xi’an is carried out. Fixed chimney structure size, along with the change of weather parameters all the day.In Lhasa,it can meet the needs of heating by close-type indoorair circulation system from 11 am to 1pm. In Xi ’an, it can’t meet the needs of heating.In Wuhan, from 10 am to 11 am, it can meet the needs of heating.(3)With the vertical wall type solar chimney as the research object, uses the FLUENT software to simulate and optimize the structure parameters of the solar chimney. The structure parameters were analyzed and studied that influenced the temperature field and velocity field of the solar chimney in two different operating mode. To the open-type all fresh air system, the chimney inlet height is 0.2m, the chimney outlet height is 0.1m, the outlet height of room is 0.2m and the chimney depth is 0.1m, it is good to enhance the heating performance of solar chimney. To close-type indoor air circulation system, the chimney inlet height is 0.1m, the outlet height is 0.1m, the chimney depth is 0.1m, it is good to enhance the heating performance of solar chimney. It can meet the demand of heat load by solar chimney in winter when the intensity of solar radiation is 300W/m2.