The Affection Of Hybrid Ventilation On Characteristics Of Airflow In Atrium Of A High-rise Residential Building

Atrium, as we know as "Patio" or "Shared Space", widely applied in many kinds of constructions for its'favorable ventilation and configuration characteristics. On the basis of the unique character of the atrium in the high-rise residential buildings, scholars lucubrated in the fields of natural ventilation, thermal comfortable, fire smoke, lighting and energy consumption, but little in the hybrid ventilation because of the complex of its theory. This paper built a computational model of a 10-story high-rise residential building with an atrium in the center, using the method of numerical simulation, to investigate the airflow in the atrium when ventilation is hybrid, which is defined as buoyancy-driven ventilation assistant with exhaust fans. According to the installation station where the fans locate, the fan installed in the atrium export called top-fan, the fan installed in the inside window called inner-window fan. Meanwhile, Orthogonal optimization is used to investigate the influence of heat source distribution, top-fan, inner-window fan and its installation position on the exhaust air rate of atrium. Finally, the simulation cases are compared with a series of experiments and the thermal comfortable of rooms which with the highest temperature or installed an inner-window fan in transitional season are simply analyzed. The results indicate that:(1) When buoyancy-driven ventilation is occurred, the heat sources located in the bottom of the building affect the airflow (both temperature and wind speed) in atrium most, no matter the heat sources distribute symmetrically or asymmetrically. In this case, the temperature and wind speed in atrium are both generally high. Occupants which locate in bottom have good ventilation.(2) Hybrid ventilation can enhance the exhaust air rate efficiently. The top-fan has the biggest influence on the exhaust volume of atrium and then the inner-window fan. The location of heat source has a bigger influence when heat sources are asymmetrical concentrated distribution and the installation position of the inner-window fan has a bigger influence when heat sources are asymmetrical decentralized distribution. Moreover, there is an interaction between the top-fan and inner-window fan.(3) The inner-window fan makes the local temperature rises and the wind speed fluctuates in the atrium but the top-fan makes the temperature of the atrium decreases.(4) According to the thermal comfortable evaluation index of natural ventilation, under the premise of 10000W calorific value, in the transitional season, on the temperature, all the occupants in the high-rise residential building within an atrium are in a good thermal comfortable extent, on the velocity, occupants are in the thermal comfortable index extent except the upper occupants or occupants which installed an inner-window fan.