实验室气流组织形式对污染物分布影响的研究

发布时间：2018-04-16 17:36

本文选题：实验室通风 + 数值模拟　；参考：《广州大学》2015年硕士论文

【摘要】：实验室作为科研工作的重要场所,通常具有能耗大、实验人员工作环境危险性大、空气污染严重等问题。另外,实验设备大量排风所带来的高能耗与局部强排风之间矛盾一直是实验室通风设计的焦点。如何有效地对实验室进行通风换气,保证局部排风设备对污染物的控制能力,达到既安全又节能的效果是实验室通风设计的重大难题。本文从实验室气流组织形式出发,利用FLUENT计算软件建立了不同气流组织形式下实验室房间的数值分析模型,并用实验数据对数值分析模型的可靠性进行了验证。就排风柜的面风速、污染物类型等因素对实验室及排风柜人体周围的污染物浓度、室内的速度、温度的影响进行了数值模拟分析。研究结果表明:送风速度及送风口与排风柜罩面间的水平距离均会影响排风柜内的气流分布;通过对密度较大污染物sf6(为空气密度5倍左右)和对密度较小的污染物NO2、NH3(分别为空气密度的1.6倍、0.5倍左右)的分析,不同气流组织形式中对实验污染物排除效果较好的是下送上回的置换通风气流组织和上送下回的混合通风气流组织形式。针对目前实验室工作人员认为排风柜面风速越大,污染物逸出的可能性越小的观念,对排风柜采用不同面风速的情况进行了数值模拟分析。研究结果表明:当排风柜面风速大于0.3m/s时,排风柜操作口的平均污染物浓度明显降低,而面风速从0.5m/s增至0.7m/s时,污染物浓度值虽有微小的降低,但排风柜性能没有明显的改善,考虑到较高的面风速大大增加了风机的能耗,不利于节能。0.5m/s的排风柜面风速已满足将污染物浓度控制在安全限值以下,完全可以保护实验人员的安全,没有必要采用很大的排风柜面风速,造成不必要的能源浪费。文中分析了不同气流组织形式下的实验室能耗。研究结果表明:在相同的实验室送风量条件下,置换通风的气流组织形式由于送风温度高,所需的制冷量低于混合通风,但是其再热能耗高于混合通风,如果在实验室应用热管等热回收装置,可以节省再热能耗。注意到置换通风的通风效率高于混合通风,且在过渡季节可延长利用室外新风免费供冷的时间,降低机械制冷的能耗。在过渡季节较长且较干燥的地区,实验室应用置换通风比混合通风具有更大的节能潜力。
[Abstract]:As an important place for scientific research, the laboratory usually has many problems, such as high energy consumption, dangerous working environment, serious air pollution and so on.In addition, the contradiction between high energy consumption and local strong ventilation caused by a large amount of exhaust air from experimental equipment has always been the focus of laboratory ventilation design.How to effectively ventilate the laboratory to ensure the ability of local ventilation equipment to control pollutants and to achieve the effect of safety and energy saving is a major problem in the design of laboratory ventilation.In this paper, the numerical analysis model of the laboratory room under different airflow organization forms is established by using the FLUENT calculation software, and the reliability of the numerical analysis model is verified by the experimental data.In this paper, the effects of surface wind speed and pollutant type on the concentration, velocity and temperature of pollutants around the body in laboratory and exhaust cabinet are analyzed numerically.The results show that both the velocity of air supply and the horizontal distance between the air outlet and the cover surface of the exhaust cabinet will affect the distribution of air flow in the exhaust tank.Through the analysis of the higher density pollutant sf6 (about 5 times the air density) and the less dense pollutant no _ 2 (NH _ 3) (about 1.6 times the air density about 0.5 times of the air density),Among the different air distribution forms, the better removal effect of experimental pollutants is the downward return displacement ventilation airflow organization and the upward and lower return mixed ventilation airflow organization form.Aiming at the idea that the larger the wind speed of the exhaust cabinet is, the less likely the pollutants will escape, the paper makes a numerical simulation analysis on the situation that the exhaust cabinet adopts different surface wind speed.The results show that when the wind speed of exhaust cabinet is greater than 0.3m/s, the average pollutant concentration of outlet is obviously decreased, while the concentration of pollutants decreases slightly when the surface wind speed increases from 0.5m/s to 0.7m/s, but the performance of exhaust tank does not improve obviously.Considering that the high surface wind speed greatly increases the energy consumption of the fan, and is not conducive to saving energy. 0.5 m / s of exhaust air speed has been satisfied with the concentration of pollutants below the safety limit, which can completely protect the safety of the experimenter.There is no need to use a large exhaust cabinet wind speed, resulting in unnecessary energy waste.In this paper, the energy consumption of the laboratory under different airflow organization forms is analyzed.The results show that under the same air supply rate in laboratory, the cooling capacity of displacement ventilation is lower than that of mixed ventilation because of its high air temperature, but its reheat energy consumption is higher than that of mixed ventilation.If the heat recovery device such as heat pipe is applied in the laboratory, the reheat energy consumption can be saved.It is noted that the ventilation efficiency of displacement ventilation is higher than that of mixed ventilation and the free cooling time of outdoor fresh air can be prolonged during the transition season and the energy consumption of mechanical refrigeration can be reduced.In the longer transitional season and drier areas, the laboratory application of displacement ventilation has greater energy saving potential than mixed ventilation.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51;TU834

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