The Analysis And Optimization Of Thermal Bridge In Self-insulation System Of Aerated Concrete

Due to the disadvantages of the external thermal insulation system andthe internal insulation system of external wall gradually appeared, the self-insulationsystem which is suitable for the climate feature in hot summer and cold winter zone iswidely recognized. With the continued innovation in the wall material applied to theself-insulation system, the energy-saving effect of aerated concrete blockin self-insulation system is the most significant. According to the continued risingenergy-saving requirements, an ultra-light aerated concrete block is developed in thisstudy by means of the initial component optimization、gas process improvement andthe parameters and system of maintenance.In self-insulation system of aerated concrete, owing to block’s low thermalconductivity, the micro-thermal bridge caused by mortar joints and the macro-thermalbridge caused by reinforced concrete is significant. Therefore, in this paper theself-insulation system of different aerated concrete is researched, which is theultra-light aerated concrete block in B04grade and B05grade or the ordinary aeratedconcrete block in B05grade and B06grade. The building energy consumption causedby mortar joint is calculated, and the topic thermal bridge is simulated by ANSYS bymeans of two-dimensional steady state heat transfer, which provide theoreticalsupport for the application in the practical engineering.The main results of this paper are in follows.(1) The thermal performance of different aerated concrete wall in self-insulationsystem affected by mortar joint is calculated. Then, the correction coefficientof block’s thermal conductivity affected by mortar joint is put forward to improve theaccuracy of energy calculation. Therefore, the correction coefficient of differentaerated concrete block in different mortar joint thickness is suggested in this paper.(2)The topic thermal bridge about the middle column and the corner post inself-insulation system of aerated concrete is simulated by ANSYS by means oftwo-dimensional steady state heat transfer. The influencing zone of the thermal bridgeis studied by changing the thickness of the insulation layer, column size and blocktypes, and simultaneously, the significance level about the heat consumption of the influencing zone is researched in different condition. The results show that theinfluencing zone of the thermal bridge of middle column is about200mm on eitherside of the column, which of the corner post is about150mm, when the thickness ofinsulation layer is not less than20mm. Meanwhile, the heat consumption of theinfluencing zone of corner post is significantly less than middle column. What’s more,the thermal bridge of middle column with the wall made of B04grade ultra-lightaerated concrete block, the proportion of heat discharge losing from the influencingzone contained in the additional heat discharge losing from the thermal bridge is up to27%. When the wall is made of B06grade aerated concrete block, the ratio can reachmore than35%. Therefore, the thermal heat dissipation of the influence zone ofthermal bridge is significant.(3)The thermal bridge structure of extending insulating layer is proposed in thispaper, which refers to the structure that the external insulating layer of the column isextended to both sides200mm. The three kinds of thermal bridge structure are studiedin different thickness of the insulation layer with different block types, which are thethermal bridge without external insulating layer, the thermal bridge with equal widthexternal insulating layer and the thermal bridge with extended external insulatinglayer, in order to realize the advantage of the thermal bridge structure of extendinginsulating layer. The results show that the thermal bridge structure of extendinginsulating layer can realize the insulation layer thickness reduction, and the reductionis more than10mm.