地下停车库通风及排烟系统数值模拟

发布时间：2018-08-13 17:51

【摘要】：随着我国经济的快速发展以及人均收入的大幅度提高,越来越多的人拥有私家车,随之而来的是更多的停车位。在一线和二线城市,土地十分紧张且价格异常昂贵,"停车难"现象随处可见。为了解决这一问题,开发商开始建造地下停车库。然而,地下空间一般是处于封闭或者半封闭的状态,很难进行通风换气,再加上汽车在地下停车库中产生的大量的污染物,这就需要选择合适的通风方式来改善车库的空气品质,这其中伴随着电力的消耗和大量的通风热损失。除此之外,由于地下停车库的相对封闭,一旦发生火灾,后果非常严重,所以一个好的防排烟系统是非常有必要的。汽车在地下车库处于怠速状态时,主要污染物CO、HC、NOx的散发量的比例大约是7:1.5:0.2,所以CO的室内允许限值和汽车的CO排放量影响着车库通风量的大小。而汽车处于启动和怠速状态时,CO的产生量受环境温度的影响很大,所以在冬、夏季节应采取不同的通风策略。具体工作如下:(1)对地下停车库自然通风进行CFD数值模拟,分别模拟出冬、夏季车库典型断面空气的温度场、浓度场、空气龄以及速度的分布云图等。可以看出:在冬季,由于车道口处有热风幕,最低温度在车道口与人行通道口处,最高温度位于热风幕出口处。CO浓度分布不均匀,离进风口较远的竖井处的CO浓度高于离进风口较近的竖井。离进风较近的竖井的自然排风的风速大于离进风远的竖井。除楼梯竖井风口的风速较大外,空气幕附近的空气流速较大,此处风速是由空气幕送风与车道自然进风合成的速度。空气龄的分布与速度、CO浓度分布相符合,CO浓度大、空气速度小的位置,空气龄大,反之亦然。在夏季,车库内的热压方向与冬季相反,夏季楼梯口形成的流速小于冬季,夏季车库内空气龄也大于冬季。车库夏季的CO浓度、空气龄大于冬季,夏季的自然通风量远小于冬季,但对于车库的CO浓度,冬夏季相差并不很大。(2)对七种不同型式机械通风组合系统进行CFD数值模拟,分别模拟出冬、夏季车库典型断面空气的温度场分布、速度场分布、CO浓度场分布、空气龄分布云图等。可以看出,诱导通风系统与其它较好的通风型式的效果比较没有优势。(3)利用CFD模拟来分析哪种方法对火灾排烟较为有利,取典型断面来分析车库内的烟气与温度的分布情况。可以看出,当火源位于500m2防烟分区中心时,两种防烟分区的排烟型式的温度、浓度分布较为接近。当火源位于2000m2车库中心时,即火源远离疏散口时,2000m2防烟分区的排烟效果比500m2防烟分区的排烟效果要好一些。
[Abstract]:With the rapid development of economy and the increase of per capita income, more and more people own private cars, followed by more parking spaces. Land is tight and expensive in first-and second-tier cities, and parking is hard to find. In order to solve this problem, developers began to build underground parking garage. However, the underground space is generally in a closed or semi-closed state, it is difficult to carry out ventilation and ventilation, plus a large number of pollutants produced by cars in underground parking garage. This requires proper ventilation to improve the air quality of the garage, which is accompanied by electricity consumption and a large amount of ventilation and heat loss. In addition, because the underground parking garage is relatively closed, once the fire occurs, the consequences are very serious, so a good smoke control system is very necessary. When the car is in the idle state of the underground garage, the emission ratio of the main pollutant COC HCN NOx is about 7: 1.5: 0.2, so the indoor allowable limit of CO and the CO emission from the car affect the ventilation of the garage. However, the amount of CO production is greatly affected by the ambient temperature when the vehicle is in the state of start-up and idling, so different ventilation strategies should be adopted in winter and summer. The main works are as follows: (1) the CFD numerical simulation of natural ventilation of underground parking garage is carried out, and the temperature field, concentration field, air age and velocity distribution of typical section air in winter and summer are simulated respectively. It can be seen that in winter, due to the presence of hot air curtain at the vehicle entrance, the lowest temperature is at the crossing and pedestrian passage, and the highest temperature is located at the outlet of the hot air curtain. The CO concentration in the shaft far from the inlet is higher than that in the shaft near the inlet. The natural exhaust wind velocity of the shaft near the inlet wind is greater than that of the shaft far away from the incoming wind. The velocity of air near the air curtain is larger except the wind speed of the staircase shaft tuyere, where the wind speed is composed of the air curtain supply air and the natural air inlet of the driveway. The distribution of air age coincides with the distribution of CO concentration at the same time as the position where the concentration of CO is high and the velocity of air is small, and the air age is large and vice versa. In summer, the direction of hot pressing in the garage is opposite to that in winter. The velocity of velocity formed at the staircase in summer is smaller than that in winter, and the air age in summer is longer than that in winter. The CO concentration in the garage in summer is longer than that in winter, and the natural ventilation in summer is much smaller than that in winter, but there is no significant difference in CO concentration in winter and summer. (2) the CFD numerical simulation of seven different types of mechanical ventilation combination system is carried out. The distribution of temperature field, velocity field, CO concentration field and air age distribution of typical section of garage in winter and summer are simulated respectively. It can be seen that the effect of induced ventilation system is not superior to that of other better ventilation types. (3) CFD simulation is used to analyze which method is more beneficial to fire exhaust smoke, and the typical section is used to analyze the distribution of smoke and temperature in the garage. It can be seen that when the fire source is located in the center of the smoke control zone of 500m2, the distribution of temperature and concentration of the two smoke control zones is close. When the fire source is located in the center of the 2000m2 garage, that is, when the fire source is far away from the evacuation port, the smoke removal effect of the 2000m2 smoke control zone is better than that of the 500m2 smoke control zone.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU962

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