| The performance of the building's transparent envelope structure has a huge impact on building energy consumption and indoor comfort degree.Advanced building transparent envelope structure should be able to dynamically adapt to environmental factors,and effectively adjust the materials and energy entering the room according to weather,user behavior and energy market prices.However,at present most of the transparent envelope structures(windows,glass curtain walls,etc.)are designed to meet traditional functions such as insulation.Because the parameters such as light transmittance and heat transfer coefficient cannot be adjusted during use,they tend to causes excessive air conditioning load and glare.In response to these problems,active light-regulating methods are currently widely used at home and abroad.These lightregulating methods often have problems such as high construction and maintenance costs,complex structures and additional energy consumption.In order to solve these problems at a lower cost,this paper proposes a bimetal passive light-regulating device,and studies its adjustment performance and actual use effect.Research shows:(1)The bimetal passive light-regulating device can passively adjust the sunlight entering the room.The transmittance adjustment range is greatly affected by the lengthheight ratio,the surface temperature of the bimetallic strip and the installation angle.The greater the length-height ratio of the device,the denser the distribution of bimetallic strips in the device,the lower the transmittance of the device,and the smaller the adjustment range.The higher the surface temperature of the bimetallic strip,the lower the transmittance of the light-regulating device and the stronger the adjustment performance.When the device is placed horizontally towards the south,if the device has a large length-height ratio,it will lose its light-regulating ability.The method of tilting towards the south can reduce the inherent shading rate of the light-regulating device and increase the deformation shading rate.(2)Experiments show that the application of bimetal passive light-regulating device can reduce the indoor temperature by about 13? during periods of strong solar radiation.The application of the device can also significantly reduce the indoor brightness at noon.The interlayer of the device plays an extremely important role in discharging excess heat in the room.Although the light-regulating device is arranged in the interlayer,the air resistance is greater,but this does not affect the natural convection of the air in the interlayer.On the contrary,the buoyancy force provided by the bimetallic sheet to the surrounding air is much greater than the air resistance generated by the device.Therefore,compared with the pure air interlayer,the interlayer with the light-regulating device has higher air flow rate and heat emission efficiency.(3)Simulation calculations show that in summer in Beijing,using bimetal passive light-regulating device can reduce the indoor heat gain by about 45% compared to ordinary rooms.While in winter,using this light-regulating device only increased indoor heat loss by 2.13%.The device can significantly reduce the indoor heat gain in summer and slightly increase the indoor heat loss in winter.(4)Simulation calculations show that the shading effect of the bimetal passive light-regulating device in summer is significantly stronger than it in winter.In the case of normal outdoor lighting,the use of the light-regulating device will not make the indoor lighting of the building lower than the requirements of normal work and life.When the application of bimetal passive light-regulating device adversely affects indoor lighting,the use of bimetallic coating with low absorption rate,reducing the installation area of the device in summer,reasonable selection of bimetallic materials and lengthto-height ratio of the device and other measures can significantly reduce this adverse effect. |
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