Research On Asymmetry Of Radiation From North To Exterior Windows Of Office Buildings In Winter In Severe Cold Regions And Improvement Measures

As a symbol of modern city,glass curtain wall has been applied more and more in highrise public buildings.In recent years,with the rapid development of China’s economy,glass curtain wall has also been used as the enclosure structure in public buildings in various cities.But in the cold region in winter in China,the outdoor environment temperature is very low,north to the solar radiation intensity is smaller,outside a window and outside window as retaining structures in the most vulnerable part of the thermal insulation performance,especially when using glass curtain wall,the wall than the big window,outside the window surface temperature is low,the formation of the cold radiation can produce local made close to the people outside the window is not comfortable.To abate this kind of local discomfort that causes by cold radiation,adopt the means that sets a curtain more at present,but the daylighting that sets a curtain to be able to affect indoor.In this paper,it is proposed that the inner surface of the external window is heated by a bottom-up attached jet to improve the temperature of the inner surface,so as to reduce the local discomfort caused by the cold radiation.For the research of using bottom-up attached with a jet heat outside the window of the inner surface temperature effects and determine the optimal location and operating mode of air supply outlet attached with a jet,in the study under different working conditions,by using numerical simulation method for various influencing factors on the room from outside the window the influence of different location of asymmetric radiation temperature,and using experimental data to validate the numerical model,On simulated data sorting summary,establishes the regression analysis data,finally the multivariate linear/nonlinear regression method is adopted to regression data regression fitting,the resulting height of 0.6 m and height of 1.2 m place outside the window the inner surface temperature forecast mathematical model,using asymmetric radiation temperature calculation model for the vertical wall attached with a jet optimal operation strategy.The main research contents and conclusions are as follows:(1)Through the theoretical analysis of heat transfer theory and attached jet flow of the external window,the influencing factors of the inner surface temperature of the external window are obtained.According to the research needs,the outdoor temperature,the distance between the attached jet air supply outlet and the external window,the heat transfer coefficient of the external window,the attached jet air supply velocity and the attached jet air supply Angle were finally determined as the influence factors for the simulation study.(2)In the asymmetric room environment caused by the cooling radiation from the outside window,the radiation asymmetry caused by the outside window comes from the horizontal direction,and the asymmetric radiation temperature gradually decreases with the increase of the distance from the outside window.Adding the attached jet to heat the inner surface of the outside window can significantly improve the asymmetric radiation temperature at different distances from the outside window.It has a good effect to improve the radiation asymmetry caused by the cold radiation of the outside window.(3)When the attached jet is used to increase the temperature of the inner surface of the outer window,the heat flow of the outer window will increase due to the increase of the air velocity and temperature near the inner surface of the outer window,resulting in partial heat loss;(4)By analyzing the influence of changing the distance between the attached jet air supply outlet and the external window on the asymmetric radiation temperature at different distances from the external window in the room,when the distance between the attached jet air supply outlet and the external window is 200 mm and 300 mm,the asymmetric radiation temperature at different distances from the external window is nearly the same.Moreover,the asymmetrical radiation temperature value is obviously larger than that when the distance between the attached jet inlet and the external window is 150 mm and 100 mm.When the distance between the attached jet inlet and the external window is 150 mm,the asymmetrical radiation temperature at different distances from the external window is the minimum.In order to improve the radiation asymmetry at different distances from the outside window in the room,the distance between the attached jet air supply outlet and the outside window can be set at 100-150mm;(5)It can be concluded that when the attached jet air supply Angle changes,the asymmetric radiation temperature at different distances from the outside window in the room can be obtained.When the attached jet air supply Angle is 60° and the attached jet air supply Angle is 90°,the asymmetric radiation temperature at different distances from the outside window is basically the same.When the attached jet air supply Angle is 30°,the asymmetry radiation temperature at different distances from the outside window is significantly greater than that of the other two groups of working conditions.For the local comfort of the sitting personnel in the office,the internal surface temperature below the height of 1.2m of the outside window can be considered,and the attached jet air supply Angle can be set between60° and 90°.(6)As the attached jet air supply velocity increases,the asymmetrical radiation temperatures at different distances from the outside window gradually decrease.When the air supply velocity is 1m/s,the asymmetrical radiation temperatures at different distances from the outside window are significantly greater than those at other attached jet air supply velocities.(7)When the other conditions are fixed,with the increase of outdoor temperature,the asymmetrical radiation temperature at different distances from the outside window decreases gradually;As the heat transfer coefficient of the external window decreases,its thermal insulation performance improves,and the asymmetrical radiation temperature at different distances from the external window in the room also decreases gradually.(8)Through multiple regression analysis(including multiple linear regression analysis and multiple nonlinear regression method),a mathematical model for predicting the temperature of the inner surface of the external window at the height of 0.6m and 1.2m was obtained,and the optimal operation strategy of attached jet device was established by using this model and the calculation model of asymmetric radiation temperature.This topic is analyzed with the method of numerical simulation study of impact factor changes external window of the inner surface temperature effects and determines the optimum position and attached with a jet device operating model,and obtained by means of mathematical statistics window outside surface temperature forecast mathematical model,in order to improve the office building outside the north cold region in winter window radiation asymmetry provides a theoretical basis.