Recently the air quality has caused people's great attention, and the appraisal of the air quality has become a hot issue in the worldwide. This paper assets that the age-of-air should be an important index to evaluate the air quality. Since the architecture place becomes more and more complicate and diversity, the traditional searching method has a lot of limitations. With the development of computer technique, the superiority of computational fluid dynamics (CFD) method becomes more and more obvious, thus the CFD begins to be applied to the HVAC.
A study obtained steady-state solutions for Rayleigh number on flow structure of buoyant flow in a roof of triangular cross-section. The heat transfer was also investigated. It was found that height-base ratio and Rayleigh number have a significant influence on the temperature and flow field.
Ventilation system has to be design in order to strike a balance between indoor air quality and energy requirements.So, the ventilation efficiency can be considered as a major issue to deal with this objective. In order to assess the efficiency of pollutant elimination from a room, a methodological approach using CPD has been developed. It is based both on local and global indexes. These indexes take into account the distribution of pollutant concentration inside room and the mean concentration at the exhaust with respect to the occupant location.
Refuge floor is specially designed in high-rise buildings for the purpose of supplying a temporarily safe place for evacuees under emergency situations. The provision of such designated refuge floor is a prescriptive requirement in the fire code of Hong Kong. Such a provision appears to be desirable by the regulators as it relates to simple rules and has administrative convenience. In order to fulfill its function, the refuge floor should be a safe place for the evacuees.
The aim of this study is to improve the utilization of CFD approach in the applications of air conditioning technology. More precisely, to establish principles and recommendations to follow in order to design air distribution systems in small enclosures at low room air changes per hour by means of CFD technique. By the use of a commercial code, Fluent, the accuracy and reliability of such a numerical simulation are elucidated in this work for a mixing ventilation system; the air supply terminal is a commercial diffuser which creates a complicated 3D - wall jet below the ceiling.
This paper is based on a dual approach (experimental and numerical) in order to predict the indoor air quality for small ventilated enclosures. The experimental part employs a ventilated test room and a tracer gas technique (constant method as gas injection) to estimate the diffusion of a pollutant. The gas used is the sulphur hexafluoride (F6S). The numerical approach is a CFD simulation, adding a convection - diffusion equation (to determine the local mass fraction of the pollutant) to the equations normally used to solve a turbulent flow.
Large eddy simulations (LES) were performed for flows relevant to or incurred in ventilation air motions with and without thermal effects. The emphasis was placed on the discussion of the possibility and potential of LES for modelling indoor air flows. Some prospective views were given on the capability and implementation of the LES approach. LES is a potential tool for providing detailed and accurate solution of turbulent flow and heat transfer in analyses of indoor environment and building energy performance.
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