Experimental Study On Thermal Bridge Effect Of Reinforced Concrete Cantilever Beam Under Air Condition

With the rapid economic development brought by economic globalization,people pay more and more attention to the use of energy and energy efficiency.Building energy consumption accounts for nearly half of the world's total energy consumption,and the energy consumption of HVAC system accounts for the main part of building energy consumption,which has a significant relationship with the thermal performance of building envelope and the heat loss caused by thermal bridge parts.The existence of thermal bridge will bring many influences to buildings.In winter,it will increase the heat loss of buildings,and in summer,it will increase the heat gain of buildings.In addition to increasing the cooling and heating load of air conditioners,it will also increase the cost of energy consumption.At the same time,thermal bridge will bring the risk of condensation to the wall of the enclosure structure,which will cause the formation of mold on the wall,or the peeling of the wall,affecting the quality of indoor life,and the aesthetics of the living environment.Therefore,it is of practical significance to study and improve the thermal bridge effect.Based on the three basic heat transfer modes and the theoretical basis of heat transfer,this paper lays a theoretical basis for the subsequent calculation.By comparing and analyzing the temperature of the inner surface of the building wall and the dew point temperature,it can be concluded that the inner surface temperature of the wall exceeds the dew point temperature in winter and there is no risk of condensation in the room.Taking the reinforced concrete cantilever beam of the existing frame structure as the research object,an experimental platform was set up to study the thermal bridge effect under the most adverse working conditions.Of winter summer air conditioning conditions of concrete cantilever beam and its adjacent wall surface,internal,and indoor and outdoor air for four days,96 hours of continuous temperature measurement,winter summer respectively experiment indoor air temperature stability in the 29 ? and 26 ?,indoor conditions remained in a stable state,outdoor conditions for the natural environment,numerical analysis and the measured results were fitted,and using method of ANSYS finite element method(fem)and heat flow density were simulated and calculated.According to the experimental results,when the indoor thermal and humid environment is in a stable state,reinforced concrete cantilever beam has obvious thermal bridge effect.The heat gain at the thermal bridge site in summer is about twice that of the external wall of the surrounding structure,and the heat loss at the thermal bridge site in winter is about three times that of the external wall of the surrounding structure.The heat flow ratio of the hot bridge site in winter and summer is 1.98:1;The heat loss of outer wall in winter is 1.22 times of that in summer.Under the standard module,the heat flux percentages of the single-sided external wall in winter and summer and the longitudinal frame beam in the single-sided external wall are 1.1:1 and 1.73:1,respectively.The continuous beam across the wall of the enclosure structure appears a temperature inflection point at a point close to the wall both indoors and outdoors.The temperature rise between inflection points in summer accounts for about 85% of the total temperature rise,and the temperature drop between inflection points in winter accounts for about 80% of the total temperature drop.The location of the inflection point is closely related to the thermal performance of reinforced concrete and the temperature difference between indoors and outdoors.The air temperature on both sides of the inflection point is not different from that inside the continuous beam.There is no change in the temperature of the inner and outer walls.At the same time,the heat transfer from the indoor to the outdoor is linear along the continuous beam.ANSYS software finite element method was used to simulate and analyze the experimental model,and the simulation results were in good agreement with the experimental results.To establish a new model based on the experimental model,and increase the corridor walls on the modeling based on the original model,the corridor walls as building exterior walls,a comparison experiment model and the simulation results of the new model,for the experimental model,the corridor space for indoor environment have the effect of heat preservation and heat insulation,the corridor is effective to reduce the heat bridge effect.