Research On Harmful Gas Control In Vector Flow Fume Hood

The chemical fume hood is an important local exhaust equipment to control harmful gas and ensure the safety of experimental personnel in the chemistry lab. There are some shortcomings of upper exhaust fume hood when it is applied as typical chemical fume hood: As vortex was easily generated under the operation of chemical fume hood, harmful gas would escape quickly, which would reduce ventilation efficiency of chemical fume hood; the control effectiveness of fume hood was different for harmful gas among different physical property. For the disadvantages of the conventional fume hood, a novel type of the vector flow fume hood what inside air flow to the inspiratory face was designed on the basis of structure optimization to eliminate the vortex and improve the ventilation efficiency and compatibility in this paper. Similarly, numerical simulation was used to explore flow field distribution and the control effect of harmful gases in the vector flow fume hood. The main research contents are as follows:(1) Considering the structure type, flow pattern and harmful gases concentration distribution of upper exhaust fume hood, the face velocity of the laboratory fume hood was measured to analysis the uniformity of it, which based upon the related literature and fieldwork. Results showed that the maximum and minimum deviations of the face velocity distribution were greater than 15%, which indicated an bad Uniformity.(2) Using CFD method to simulate the distribution characteristic of the flow field of the upper exhaust fume hood. After comparing simulation results of the face velocity with experimental data, we found that the error was not more than 10%, thus the correctness of numerical method was verified.(3) Exhaust air rate, setting location and density of harmful gases were influencing factors which affected ventilation efficiency of the upper exhaust fume hood. In addition, NH3 and Cl2 diffusion characteristics were analyzed in the upper exhaust fume hood on the bases of studies above.(4) A novel type of chemical fume hood-vector flow fume hood with ventilation performance and compatibility was designed owing to proper structure optimization of the upper exhaust fume hood. Besides, numerical method was used to investigate the flow field and harmful gas concentration distribution of the vector flow fume hood. Results showed that the vector flow fume hood was good to improve the distribution of flow field and eliminate the vortex, as well as capture different densities of harmful gases effectively.