Study On Ventilated Quantity And Air Distribution Of Underground Garage

Underground parking garage is being built with the serious problem of parking in ground of urban. The underground garage is in a closed or semi-closed state and the sun and the air of outside are very difficult to enter the garage, making the contaminant concentration in garage exceeded discharge standard and affecting human body health. There are many types of pollutants in the garage, where the number of CO is the largest.So CO is the most harmful pollution to human health in garage. Therefore CO is usually used in the design of ventilation in underground garage. As long as the concentration of CO is within the allowable range, then the concentrations of other pollutants in the garage must be within the allowable range.Because of the influence factors of pollutants concentration in the garage are so many as well as the concentration of pollutants in the garage has a lot of dynamic characteristics, so in determining the amount of ventilation in the garage, various factors should be taken into account. With the improvement of gasoline quality, the number of pollutants released by cars also will be reduced. The traditional method of using ACH in garage ventilation will inevitably result in the waste of energy. In this study, comprehensive ventilation method is used to determine the required amount of ventilation in the garage. By comparing various empirical formula, we finally get an ideal method of calculating the amount of ventilation.With the growing of underground garage in the city, the energy consumption also cause for the concern of person. In the study of garage ventilation, the energy generated by ventilation should be taken into account. China's building energy consumption accounts for a sizeable proportion in total energy consumption. Therefore, in the selection of the underground garage ventilation, we should not only to consider airflow effect and health requirements of person, but also the economy, because energy waste will pollute the environment.Because of natural ventilation susceptible to the external environment and has poor ventilation, so it is usually replaced by mechanical ventilation in the underground garage ventilation design. The two mechanical ventilation methods widely used for the underground garage ventilation design are traditional duct induction and non-duct induced ventilation, both of them have their advantages and disadvantages. Underground garage can be divided into four types based on fire rating. This article will research on the airflow of a III class underground garage in Shenyang. Contrast duct ventilation system and no-duct inductive ventilation system, set the duct ventilation into two air distribution mode, they are middle air supply and air supply on one side. Give the comparative analysis of the effect of airflow as well as the ability to exclude contaminants in the three air distribution way.The application of numerical simulation in air distribution analysis has been very mature. In this paper, FLUENT is used to simulate the velocity field and CO concentration field in the garage and then TECPLOT is used for processing. Finally, by evaluating its airflow, we can get the ventilation suitable for the researched garage and thus provide the basis for the ventilation design of this type of underground garage.In recent years, the upper 1/3-1/2 and lower 1/2-2/3 exhaust way is usually used in the choice of exhaust way of underground garage ventilation. But many studies have called into question. There has been a long time since the norm is established and there is no norm for the ventilation mode during this period. Research has shown that the density of CO in the garage were similar to air density. The emission temperature of CO from motor vehicles is high, the high temperature CO will float in the upper part of garage. So setting up lower exhaust will increase the initial investment and result in waste of energy. In this paper, through analyzing the mechanism of the vehicle fuel combustion and exhaust emissions mechanism, it is concluded that automobile exhaust emissions are mostly in the upper part of the garage. Therefore, in the design of the exhaust port, it is only needs to set on upper exhaust port in the garage.Finally, through the study of the air distribution evaluation of simulation results, it is concluded that induced ventilation way is better than of duct ventilation way in exclude contaminants. In the two different air distribution forms of duct ventilation, middle air supply way is better than air supply on one side.