Research Of Buoyancy-driven Effect And Elevator Piston Effect On High-rise Buildings In Winter

In modern times, the air-conditioning system is used in the public buildings for heating in winter. The air-conditioning system could theoretically keep the indoor pressure positive. However, with the increasing height of the modern buildings, especially that a large number of super high-rise buildings have been built, the buoyancy-driven effect and the elevator piston effect on the building indoor wind environment and thermal environment are more and more serious. So this paper discusses the buoyancy-driven effect and the elevator piston effect on the building indoor wind environment and thermal environment.In this paper, the formation principle, development history and the present study were reviewed and commented briefly at first. Then the high-rise building model and the super high-rise building model were developed by CFD for analyzing the buoyancy-driven effect and the elevator piston effect on the building indoor wind environment and thermal environment. The calculation results show that: in the high-rise building, due to the heat supply of central air-conditioning system and the buoyancy-driven, the relative pressure of all air-conditioned rooms is kept positive and the stack effect occurs in the vertical shafts; the piston effect of the elevator cab on the pressure difference across the exterior envelope is very small, but it significantly affects the pressure distribution in the elevator shaft, the pressure difference across the elevator door and the pressure difference across the landing door; compared with the high-rise building, the buoyancy-driven effect is much more serious, that when the inner doors of the super high-rise building keep 1/2 opening situation, most of the rooms cannot meet the design temperature and the pressure difference across the landing door exceeds the upper limit; keeping the exterior doors closed and increasing the air supply volume of the first floor can weaken the buoyancy-driven effect on the first floor, but they work hardly for the other floors; supplying air in elevator shaft can keep the room meeting the design temperature, but it will enlarge the pressure difference across the landing door, which is likely to cause some security issues; when the inner doors were closed, that the transverse barrier was enhanced, the rooms except for the first floor can meet the design temperature; when the inner doors were closed, increasing the air supply volume of the first floor can keep all the rooms meeting the design temperature; and we suggest that keep the inner doors closed as far as possible in the use of the super high-rise building.The results of this study provide basic measures and theoretical basis for optimizing high-rise building internal airflow and reduce security incidents.