Thermal Bridge Analysis And Optimization Of Assembled Frame Shear Wall Structure In Hot Summer And Cold Winter Region

In order to meet the development requirements of building industrialization and reduce building energy consumption,our country put forward the requirement of developing assembly building during the13th Five-Year Plan.Assembly building has the advantages of time saving,energy saving,water saving,material saving,environmental protection and so on.It belongs to green energy saving building.In energy-saving building,thermal bridge was the main cause of heat loss of enclosure structure.In order to further improve the energy-saving effect of assembled building,this paper takes the assembled concrete wall structure in hot summer and cold winter as the research object.The FLUENT software was used to simulate the thermal performance of the wall in order to clarify the influence of grouting sleeve on the thermal performance of the building wall.The thermal bridge effect of assembled frame shear wall structure and T-shaped floor structure under the conditions of internal insulation,external insulation and sandwich insulation is quantitatively and qualitatively analyzed.The main research work is as follows.1.In this paper,the thermal performance of the assembled frame shear wall without heat preservation is studied and compared with that of the ordinary reinforced concrete structure.It was found that the arrangement and quantity of sleeve have an important effect on the wall surface temperature.The closer sleeve is to the wall surface,the lower the surface temperature is,the greater the heat flux density is and the more obvious the thermal bridge effect is.In the absence of heat preservation,compared with the conventional reinforced concrete structure,the existence of sleeve reduces the overall thermal resistance and increases the heat transfer coefficient of the assembled wall.Through the comparison with the experimental data,it is found that the experimental results are in agreement with the numerical simulation results.2.The thermal performance of assembled frame shear wall structure and T-shaped floor structure under different insulation modes was simulated and analyzed qualitatively and quantitatively according to the problems of thermal bridge.Under the external insulation system,the wall heat preservation effect is the best,the wall heat resistance is large,the heat transfer coefficient is small,can effectively avoid the emergence of thermal bridges,meet the building energy saving requirements of 65%in hot summer and cold winter area,and the temperature inside the wall was stable.The wall has no risk of condensation.Under the sandwich insulation system,due to the discontinuity of the insulation layer in the frame column,the shear wall was greatly affected by the frame column thermal bridge,and the thermal bridge had a range of up to 43 mm.The degree of heat loss in the affected area was 24%,and the lowest surface temperature in the wall was 13.55℃,which had a certain risk of condensation.Although the assembled T-shaped floor structure also stores the discontinuity of the insulation layer under the sandwich heat preservation system,due to the addition of elastic waterproof material with low thermal conductivity at the joint,the heat loss was effectively reduced.Make it have the same heat preservation effect as the external heat preservation.Under the condition of internal heat preservation,both the assembled frame column structure and the T type floor structure have the problem of intermittent insulation layer.The heat concentration is lost from the frame column and the floor,and the phenomenon of thermal bridge is obvious.The heat transfer coefficient of frame column was up to2.5W/m~2·K,and the lowest temperature of inner surface was 10.61℃.In the T-shaped floor structure,under the internal thermal insulation system,the heat loss in the affected area of the heat bridge was 39.9%,the affected area of the heat bridge was about 280 mm,and the minimum temperature on the inner surface of the wall was 11.55℃.Both of them have great condensation risk.3.Based on the thermal bridge effect of the assembled wall structure under the internal insulation and sandwich insulation system,the thermal insulation structure with different thickness was designed for the thermal bridge.Taking the most common sandwich insulation system of the assembled building as an example,the external thermal insulation of the assembled frame shear wall structure with different thickness was simulated and compared.Compared to thermal bridge without external insulation,it was found that the heat transfer coefficient of shear wall can be reduced by 39.3%,44.7%,48.3%,and the heat transfer coefficient of frame column can be decreased by 45.9%,59.8%,and 78.4%,when there was external insulation of 20 mm,40 mm,and 60 mm respectively.At this time,the thermal bridge thermal insulation above 40mm,the assembled frame shear wall structure can meet the requirements of building energy saving in hot summer and cold winter area.When the thickness of the thermal insulation layer outside the thermal bridge was60mm,the maximum influence range of the thermal bridge can be reduced to 0mm.