Numerical Investigation On A Solar Chimney With Slot Outlet

Every country in the world is actively using renewable energy such as solar energy,wind energy,geothermal energy,biological energy to achieve building energy efficiency with the rapid increasing of the ratio of building energy consumption to human total energy consumption,because of the rapid development of the Chinese economy and the continuous improvement of people's living standard.Solar chimney is a device that utilize solar energy to increase the air temperature of channel to reach natural convection,and then induced the air of channel flow out channel,it has many different usage,and is an efficient way of building energy saving.In this paper,a solar chimney with slot outlet was introducd,and its natural ventilation performances based on the coupling action of wind pressure and thermal pressure was analysised theoretically,and then a mathematical-physical model was established,the ventilation performance of solar chimney based on the coupling action of wind pressure and thermal pressure at different structural parameters and different meteorological parameter was studied through numerical simulation.The major contents and findings were as follows.(1)The mathematical and physical model of a vertical solar chimney with slot outlet and an inclinable roof solar chimney with slot outlet were established;The computational domain size of outdoor wind field was confirmed;The fluid flow regions were meshed,and the grid independence was tested and verified;The experiment date and the simulation date were contrasted to verify the reliability of computing methods.(2)The result showed that the vertical solar chimney with slot outlet can use solar energy and wind energy to improve natural ventilation by studing the natural ventilation performances of the vertical solar chimney with slot outlet.As far as this study is concerned,its mass flow rate increased to up to 171.0%when compared to traditional solar chimney.(3)The effects of structural parameters to the performance of the vertical solar chimney with slot outlet were shown below.With the increase of the ratio(h2/h3),the mass flow rate firstly decreased negatively,then increased positively,and then decreased after increasing to some extent,there was an optimum ratio(h2/h3)at around 1 for the maximum of mass flow rate;With the increase of the ratio(w2/s1),the mass flow rate of the solar chimney under different solar radiation intensity firstly increased and then decreased,the ratio(w2/w1)at around 0.25 for the maximum of mass flow rate were same.(4)The effects of meteorological parameters to the performance of the vertical solar chimney with slot outlet were shown below.Outdoor wind speed and solar radiation intensity had gain effect to solar chimney at reasonable structural parameters,it could increase the mass flow rate and absolute value of pressure differences between the inlet and outlet;The mass flow rate of the solar chimney firstly increased,and then decreased with the increase of the outdoor wind direction,the optimum outdoor wind direction was different under different structural parameters.(5)The result showed that the inclinable roof solar chimney with slot outlet could use solar energy and wind energy to improve natural ventilation by studing the natural ventilation performances of the inclinable roof solar chimney with slot outlet.As far as this study is concerned,its mass flow rate increased to up to 49.0%when compared to traditional inclinable roof solar chimney.(6)The effects of structural parameters to the performance of the inclinable roof solar chimney with slot outlet were shown below.The induced effect of outdoor wind in formation of the solar chimney would decline continuously with the increase of the ratio(h2'/h3'),there was an optimum ratio(h2'/h3')at 0 for the maximum of mass flow rate;With the increase of the ratio(w2'/w1'),the mass flow rate of the solar chimney under different outdoor wind speed firstly increased and then decreased,and the ratio(w2'/w1')at around 0.125 for the maximum of mass flow rate were same under different outdoor wind speed.(7)The effects of meteorological parameters to the performance of the inclinable roof solar chimney with slot outlet were shown below.Outdoor wind speed and solar radiation intensity had gain effect to solar chimney at any structural parameters because outdoor wind could not flow in room,it made the mass flow rate increases;The mass flow rate of the solar chimney firstly increased,and then decreased with the increase of the outdoor wind direction,the optimum outdoor wind direction was different under different structural parameters.