| Building envelope energy consumption accounts for a large proportion of building energy consumption, which is one of the key of the building energy saving, so the development of new energy saving wall is of great significance to building energy saving. The impact of the wall on the indoor thermal environment, mainly due to the wall with "thermal compatibility" and "thermal resistance". At present, most of the research on the envelope structure is based on the two properties of the wall. Conducting research of "thermal compatibility" wall such as phase-change wall etc. and in the research of "thermal resistance" wall such as solar water curtain wall and so on. However, the heat transfer coefficient of the wall is almost constant in the study of the "thermal resistance"(i.e., the heat transfer performance) of the wall at present. Which wall can be in outdoor temperature fluctuation is small and the outdoor temperature more extreme areas (such as cold regions or areas with hot summer and warm winter) to achieve a good energy saving effect. However, in areas with large outdoor temperature fluctuations, the energy saving potential is limited. In the area of Xinjiang province, the summer daytime outdoor temperature is very high. In order to reduce the energy consumption of air conditioning, it should reduce the heat flux through the wall into the room, so the heat transfer coefficient of the wall is the smaller, is the better. In the summer night when the outdoor temperature is too low, in order to reduce the air conditioning energy consumption, should increase the heat conduction through the wall, so the heat transfer coefficient of the wall is the greater, is the better. At the present because of the stage of building exterior wall, the heat conduction coefficient is fixed, can not achieve such a way of energy saving. In order to further reduce the energy consumption of the wall and the innovation of this paper is to put forward a new type of retaining structure, heat flow self regulating envelope. The building envelope can change itself heat transfer coefficient of the structure according to the outdoor temperature, to reduce the load of air conditioning heating and reduce the role of building energy consumption. In order to find out and master the heat transfer characteristics of the heat flow self regulating envelope, this paper mainly studies the heat transfer characteristics of the heat flux from the three aspects of the experimental research, theoretical analysis and numerical simulation:(1) The heat flux and heat transfer performance test bench was built, and the experimental test was carried out. Test includes two conditions:high resistance condition (i.e. simulated outdoor climate temperature higher than room air conditioning indoor temperature conditions) and a low thermal resistance condition (i.e. simulated air-conditioned room temperature is higher than the outdoor temperature conditions). By comparing the variation of thermal resistance and equivalent heat transfer coefficient of the two conditions, the feasibility of the change of heat transfer coefficient of the wall is preliminary analyzed. The testing shows that using the form of double metal sheet of heat flow self regulating retaining structure, average can achieve 30% resistance change rate. It is proved that the regulation resistance is feasible, follow-up study by means of reducing the contact thermal resistance and so on, can make changes to further improve.(2) The influence factors of heat transfer of the heat flux self regulating retaining structure are studied by using the theory of heat transfer. The heat conduction model and the natural convection heat transfer model are established for the heat flow and self regulating structure. Application of the two models of heat flow self regulating the thermal resistance of the wall change rate were analyzed. Analysis of the relationships between interlayer thickness, bimetal heat transfer coefficient, double metal layers, different steady-state temperature factors on heat resistance change rate. The theoretical calculation results show that, when the bimetallic strip thermal conductivity variation range 10-170W/(m2·K), bimetallic strip layers range from 1 to 14, the variable resistance layer thickness range 10～170mm conditions, the heat conduction radiation model of variable resistance layer resistance change rate range 1～16 times. In the variable resistance layer thickness range of 10～100mm, the natural convection heat transfer radiation model of variable resistance layer resistance change rate is 1～29times.(3) By means of numerical simulation, the effects of different temperature, different thickness of the sandwich layer, the deflection angle of bimetallic strip and the heat transfer coefficient of bimetallic strip are the heat transfer characteristics of the variable thermal resistance layer were researched. Numerical analysis results show that when bimetallic strip thermal conductivity variation range 50-200W/(m2·K), thermal resistance interlayer thickness variation range of 100～200 mm and variable resistance layer heat transfer temperature change range of 4～20℃ conditions, the variable resistance layer resistance change rate range 9-21 times. And concluded that the optimum thickness of the variable thermal resistance layer is 100mm, the thickness of the bimetallic strip and the number of bemetallic strip shall be determined according to the economic conditions of the conclusion.In this paper, a new type of energy saving mode of building envelope is proposed, and it is analyzed by experimental research, theoretical research and numerical simulation. The feasibility of the bimetallic strip heat flux self regulating retaining structure is studied, and the preliminary obtained bimetallic strip thermal conductivity, bimetallic strip deflection angle and the thickness of the layer of bimetallic strip heat retaining structure of the self regulating effect of thermal resistance, which research lay a foundation for further research on the heat transfer characteristics of the heat flow and heat transfer characteristic of the climate adaptation function. |
PDF Full Text Request