The Analysis Of Thermal Bridge Heat Transfer In Hot Summer And Cold Winter Zone

In the area of hot-summer and cold-winter zone, there are three common thermal insulation types, including external insulation, interior insulation and self-insulation. Thermal bridge forms are varied. The existence of the thermal bridge increases the rate of heat transfer through exterior protected construction. And the accurate calculation of heat transfer of thermal bridge is the basis of the quantitative evaluation of building energy consumption level. The research on thermal bridge in hot-summer and cold-winter zone was normally restricted to one-dimensional heat transfer method, namely to consider influence of thermal bridge by area weighted method. However, with the development of energy conservation, more and more high performance and high temperature heat insulation material start to be applied, then two-dimension and three-dimension influence of the thermal bridge become more obvious. Therefore, it is necessary to attach importance to the research on heat transfer of thermal bridge.There are many different kinds of thermal bridge which are closely related to the climate conditions. In this paper, based on the weather conditions of Wuhan in winter, the representative exterior wall construction thermal bridge(mid-column and beam thermal bridge) was adopted, divided into three kinds of forms including external insulation, interior insulation and self-insulation. The finite element analysis software of ANSYS was adopted to analyse the heat transfer of different models. According to the characteristics of the temperature field and heat flux density field, thermal bridge influencing area was obtained, and the additional thermal bridges heat flow and degree of heat loss in thermal bridge influencing area was also acquired by adopting integral on heat flux.Two aspects were compared: the first one is the difference of heat transfer of the same thermal bridge in three types. The results illustrate that, for mid-column thermal bridge, the effect of external insulation is best, self-insulation using the high-performance B05 aerated concrete block is second, interior insulation rank last but with the minimum area. For thermal bridge beam using external insulation can effectively block the generation of thermal bridge. The second comparison is the influence of thermal bridge heat transfer with the same insulation form and changing parameters, adopting different thickness, different kinds of insulation materials, different column width and height(or beam height) and different block types to make simulation analysis. It is concluded that, the impact of thermal bridges is the biggest change in the thickness of the insulation and the use of insulation materials. The external insulation system reduce significantly the influence of thermal bridges. For internal insulation system, the most important impact is the change of thermal insulation layer. Thermal bridges additional heat flux is excessive, this defect can be improved through the insulation layer extends inwardly. For self-insulation, the most important one is the change of thermal insulation layer and block types. If both sides of the insulation layer extends 200 mm, can effectively block the thermal bridge.The research above provides the theoretical foundation for energy-saving design, and improves the construction on the basis of the size of thermal bridge influencing area and degree of heat loss.