建筑门窗玻璃幕墙传热系数现场测试研究

建筑门窗玻璃幕墙是建筑围护结构节能最薄弱部位,其传热系数目前只能在实验室通过热箱法测定,在现场准确、快捷地测试该值对于建筑的节能评估改造具有重要意义。在现场测试门窗幕墙内外空气温度和表面温度的基础上,推导出了基于"准稳态"测试原理和"热阻法"、"表面温度法"、"传热系数法"3种传热系数现场测试方法,现场测试值与实验室检测值的较高一致性表明了该现场测试方法的准确性,连续测试数据与平均值的较小偏差表明了该测试方法的稳定性。研究结果表明,建筑门窗玻璃幕墙传热系数可通过该方法在现场准确、快捷地测试得到。

Field Test Methods on Thermal Transmittance of Windows,Doors and Glass Curtain Walls

Windows, doors and glass curtain walls are the weakest and crucial energy - saving component of building envelope. According to the calculation, the heat loss of the windows and doors accounts for 40%~50%of the enclosure structure, which accounts for about 1/4 of the building energy consumption. At present, insulation of windows and doors is obtained only through the calibration hot box method for the determination of stability based on the heat transfer principle in the laboratory in China. There is no field test method for the heat transfer coefficient of windows, doors and glass curtain walls, which are main structural parts, the heat transfer coefficient of domestic envelope field test mainly concentrated in the wall. The accurate and convenient measurement of the heat transfer coefficient of the windows, doors and glass curtain walls has important value for the detection and identification of the thermal insulation performance of the new windows, doors and glass curtain walls and the energy-saving diagnosis of the existing windows, doors and glass curtain walls. Based on the calculation formula of heat transfer coefficient of external windows and doors and glass curtain walls, combined with the principle of heat transfer, the field test method of heat transfer coefficient for windows, doors and glass curtain walls is deduced, the verification analysis is carried out. Windows, doors and glass curtain walls are light thin-walled members;their thermal inertia is small, the peak value of the indoor air temperature, the inner surface temperature curve of glass and the window frame changing with time, which is almost consistent with the outdoor air temperature curve, so it can be considered at anytime is "quasi steady". The paper deduces the heat transfer coefficient of building windows, doors and glass curtain walls field test of"resistance", "internal surface temperature method" and "heat transfer coefficient method", the calculation formula, and analyzes its advantages, disadvantages and applicability. The test adopts a temperature heat flow data acquisition instrument, which is mainly composed of 64 temperature heat flow itinerant detectors. It is equipped with six pieces of heat flow meter and 48 Pt1000 platinum resistance temperature sensors. The field test process is mainly to arrange the temperature sensor and heat flow meter, and then the acquisition instrument automatically collects and records the data. In order to improve the testing accuracy, six temperature sensors are evenly installed on the glass surface by area. Two heat flow meters are fixed on the surface of the glass, the horizontal frame and the vertical frame, respectively, about 150 mm to 300 mm from the window surfaces. Field tests of the external window or curtain wall of three projects are carried out. The actual test results show that the field test value is consistent with the laboratory test value, and the stability is high, which can fully meet the requirements of field testing. Theoretical study and field test data show that the door, window and glass curtain wall' s heat transfer coefficient based on the quasi steady state principle and field test has a high accuracy and stability, it is important to further study on site testing method for heat transfer coefficient of doors, windows and glass curtain wall.