Research On Thermal Environment Characteristics Of Double Curtain Wall Building Under Intermittent Air Conditioning Mode

As a climate adaptability transparent maintenance structure,the double curtain wall has been widely applied in large office buildings and public buildings which in hot summer and cold winter zone because of its beautiful appearance and high daylighting performance.Compared with single glass,the double curtain wall not only have the effect of heat preservation in winter,but also take into account the characteristics of heat insulation in summer.The thermal characteristics of double curtain wall building are closely related to the reasonable ventilation mode and temperature fluctuation of curtain wall.Generally,the research for double curtain wall often based on the state that indoor temperature is constant.But indoor temperature is in fluctuation while building’s equipment is in operation actually.The double curtain wall is effected by inside and outside two-way temperature waves,and its thermal environment characteristics is different from the state which indoor temperature is constant.Firstly,this paper makes a theoretical analysis of heat transfer and flow coupling problem on double curtain wall.Each wall surface heat balance equation of enclosure structure is established based on the principle of energy conservation.The thermal balance process of each double curtain wall and the air heat balance of the whole room also were described in detail.Moreover,the heat transfer process under the action of bi-directional temperature wave is decomposed into three single thermal processes: simple stable heat transfer process,simple outside harmonic effect and simple inside harmonic effect.The outside and inside harmonic effect were described in detail.Secondly,the building energy consumption simulation software EnergyPlus is used to simulate the double curtain wall building under the periodic thermal action of unsteady state.Numerical method and experiment research were carried out about transition season operation mode(mode A and B),winter mode(mode C and D),summer mode(mode E)of double curtain wall.The deviation is been quantified analysis from experiment data.Mean bias error,root-mean squared error and coefficient of determination were considered for verification of the simulation result in predicting cavity temperature,room natural temperature and airflow speed.The results show that good agreement between simulation and experiment results,with 80% of matching degree in temperature and 75% in air velocity.Thirdly,the thermal environment characteristics of the double curtain wall under the mode of intermittent air conditioning in winter and summer are studied.The change characteristic of room temperature and surface temperature and cavity temperature is described by trigonometric function.According to the experimental results,the fluctuation period of room temperature in winter is greater than that in summer,and the preconditioning time in summer is shorter than that in winter.There is no significant change in the temperature delay time in the winter conditions,and the two operating modes are less affected by the outdoor temperature wave.The surface temperature and cavity temperature in summer are greatly influenced by outdoor temperature,and time of peak temperature lag behind.