VENTILATION DESIGN FOR UNDERGROUND CAR PARKS

Ventilation design for underground car parks is studied, first through a brief review of the ventilation requirement. Carbon monoxide concentration is believed to be the most important chemical species to be considered. Some results on field measurement of underground car parks reported in the literature are reviewed. The well-mixed model, which is a basic design model for studying the transient variation of carbon monoxide concentration, is described. The model is then revised to describe multiple sources of emission for several cars staying in a car park. with their internal combustion engines operating. Two mixing models proposed by Sandberg 1981)-Model 1, based on and displacement ventilation system and Model 3, based on (1 ventilation system with a short-circuiting air flow path-are applied to study the ventilation design in car parks. The technique of computational fluid dynamics is used to verify those existing models and then to compute the mixing factors concerned. Key system performance parameters are calculated, and a set of graphs relating those system performance parameters with the input design data is presented. These graphs can be used for designing the required ventilation rate for the system under different carbon monoxide loads. Eight local car parks are surveyed to illustrate the application of the model. Field measurement data on underground car parks, as described above, are reviewed and applied to justify the mixing models.