The airflow pattern and thermal comfort in a naturally ventilated classroom were predicted using CFD techniques. The CFD model for turbulent flow consists of equations for the conservation of mass, momentum and thermal energy and the equations for the k-E turbulence model, taking account of the effects of buoyancy and obstacles in the room. The thermal comfort was assessed according to the predicted mean vote (PMV) and predicted percentage of dissatisfied (PPD).
A mathematical model has been developed which will facilitate the prediction of infiltration rates within multi-zone buildings. The aim was to cater for: (i) significantly different temperatures in different parts of the building; (ii) flow paths at any height, including vertical connections between zones; and (iii) flow paths extending over large vertical distances. These aims led to the requirement in the associated computer program that the variation of pressure with height be accounted for independently within each zone of the building.
This paper describes the application of numerical models to predict the ventilation rate and internal air movement patterns for a naturally ventilated industrial building and compares the results with measured data. Two modelling techniques have been employed. Firstly, a zonal network model (HTBVent), using leakage area data derived from fan pressurisation measurements, was used to predict the time varying ventilation rate in response to variations in wind velocity and internal-external air temperature difference.
This report describes tracer gas measurements of the local mean age of air at different locations within an office room. These results are used to assess the distribution of fresh air atdifferent depths, and to give guidance on the depth over which single-sided ventilation is effective.
Mechanical devices such as exhaust fans and air handlers interact strongly with natural infiltration. In the past, the effects of mechanical systems have either been treated separately from those of natural infiltration or have been combined using simple models. This paper extends the theory of the interaction of unbalanced mechanical systems with stack-driven infiltration. The effects of leakage distribution and the flow exponent on fan efficiency are discussed. A simple model for combining the two effects is presented and compared with two previously proposed models.
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