Study On Natural Ventilation Performance Of An EAHE Combined With Solar Chimney

The widespread use of air-conditioning system has greatly increased the energy consumption of buildings and led to serious building sickness syndromes,which has caused people complaining about indoor air quality(IAQ).The solution to the two problems of high building energy consumption and poor IAQ is to design and develop a new type of passive ventilation and cooling technology for buildings.The new passive ventilation and cooling technology should have the functions of reducing building heat gain,strengthening building heat dissipation and providing fresh air for the building.By combining the solar chimney(SC)with the earth-to-air heat exchanger(EAHE),a new passive ventilation and cooling system is established which meets these requirements above.This system can improve the indoor thermal environment and reducing the energy consumption of building air-conditioning significantly in summer.If the SC is used in conjunction with EAHE and the building,the building maintenance structure can reduce and delay the heat input into the room.The buoyancy force produced by the SC and the building heat storage can motivate the airflow cooled by EAHE.EAHE is the connection of building and the heat sink(stratum),which is used to introduce fresh air into indoor environment and release redundant heat to the soil.This paper mainly studies the feasibility of the combined effect of SC and building heat storage to produce buoyancy force to drive EAHE for natural ventilation,analyzes the role of different buoyancy force in the natural ventilation process,and study the indoor thermal environment of the building under the regulation of the coupled system.To provide a scientific basis for the better integration of SC and EAHE with buildings,this article mainly carried out the following work:(1)Verify the feasibility of the SC with the building heat storage to produce buoyancy force to drive natural ventilation under the EAHE.Both buildings and SC have the ability to produce buoyancy force to drive indoor air flow to improve indoor thermal environment and IAQ.Through theoretical analysis and full-scale experimental research,this paper verifies the combined effect of SC and building heat storage to produce buoyancy force to drive natural ventilation under the EAHE.And a numerical model of buoyancy-driven natural ventilation coupled with SC,building and EAHE is established.(2)The mechanism of natural ventilation combined with SC-EAHE system is revealed.The buoyancy force produced by building and SC are involved in the natural ventilation process.In this study,the effects of different buoyancy forces on the natural ventilation process and the way they affect natural ventilation and cooling performance of the coupled system are analyzed.Additionally,the indoor thermal environment characteristics under the building heat storage and natural ventilation are analyzed.(3)Quantitative analysis of the influence of different parameters on the performance of the buoyancy-driven ventilation of the coupled system.As a purely passive thermal natural ventilation system,SC and EAHE interact with each other,and its working mechanism is much more complicated than that of SC or EAHE alone.Based on the established natural ventilation model of the coupled system,the influence of factors such as solar radiation intensity,ambient air temperature,stratum temperature,chimney geometrical size and EAHE geometrical size on system performance are studied.(4)The indoor thermal environment of buildings throughout the year under the action of the coupled system are studied.In addition to focusing on the ventilation and temperature drop in summer and improving the indoor thermal environment,this paper also studies the variation of natural ventilation of the coupled system during the annual cycle and the cooling and preheating potential of outdoor air,and analyzes the variation law of indoor thermal environment of the building under the regulation of the coupled system.