The Application Of Solar Chimney For Strengthening Natural Ventilation In Multistoried Building

Natural ventilation, the main mean to improve indoor air quality and reduce air conditioning energy consumption, is widely used in modern buildings, while ventilation only based on natural forces is usually affected by many uncertain factors. Therefore, the research on how to use natural ventilation effectively to improve ventilated performance with required equipments while with little energy consumption is on the summit of development agenda. Solar chimney caters to this agenda, it uses solar radiation to heat the air inside the chimney to provide buoyancy, and then promote air flow. Natural ventilation enhanced by solar energy is energy-saving. This paper focused on the research on the feasibility of applying solar chimney to natural ventilation in multi-storey buildings, numerical simulation was used to simulate the operation performance. Then some suggestions on the chimney shortcomings were proposed.This paper taken Trombe solar chimney as an example, based on climatic conditions in Changsha, k-εturbulence model and standard wall function were chosen to simulate the steady flow of natural ventilation enhanced by solar energy. Due to the differences of ventilation effect between different layers in multi-storey buildings, we set the ventilation rate at the entrance as building ventilation rate of each layer, and analyzed chimney air flow conditions under different conditions. Simulation results showed that each layer ventilation rate was various; the first floor ventilation rate was greater than that of second floor. When solar chimney was used in two-story building, there existed the optimal width where the ventilation rate of chimney entrance reached the maximum rate. When chimney stretched to three or more layers, the inlet and outlet could give rise to counter flow which was harmful to the improvement of ventilated performance.Due to the shortcomings of Trombe solar chimney when used in multi-storey buildings, like counterflow etc., we proposed three ways to improve the performance of natural ventilation enhance by solar energy and validated them. The research showed that the ventilation rate of divided solar chimney was independent, while the ventilation rate of first floor was smaller when compared with connected solar chimney. In Trombe solar chimney system, changing the second floor inlet obliquity could decrease ventilation rate of each layer, which would be of help to improve air flow states. Integrated solar chimney could improve the ventilation performance obviously; ventilation rate of each layer could increase, and prevented the drawback of lots of counterflow.Based on air charg rate, the applicability of solar chimney was researched.For Trombe solar chimney system, the effect on ventilation rate of each layer of was unbalanced, it could not be used in usual buildings. Integrated solar chimney could be used in various buildings for its uniform ventilation of each layer.