Study On Optimization Of Air Distribution Scheme For An Welding Workshop With Displacement Ventilation In Automobile Factory

In recent years, automobile manufacture has developed very rapidly in China and become one of the important pillar industries of our national economy. And the use of aluminum alloy in automobile manufacturing become wider and wider. The welding technology of aluminum alloy.is one of the most critical processes in modern automobile manufacturing procedure. MIG welding is an important method to process aluminum alloy, but massive aluminium alloy wielding soots maybe generated during welding process, including Al2O3 as principal constituent. Wielding soots may bring about severe harm to human health. Therefore, it is necessary to install ventilation system to control the concentration of aluminum alloy in welding workshop, to improve the working environment and to enhance welding workers's the product efficiency.Aluminum alloy welding workshop of modern automobile manufacturer is of large span big and great height, in which heat and contaniminant always occur simultaneously on welding spots. It is proper to adopt displacement ventiltion system in the workshop. Thus air in the occupied zone is fresh and contaniminated air flows upwards and accumulates in the above non-occupied zone. There exists indoor thermal stratification.However air distribution scheme may have greatly influence on ventilation effect of the workshop with displacement ventilation system.With the same air supply parameters, different air distribution schemes may bring about different temperature, velocity, relative humidity and contaminant concentration fields in the workshop. Therefore, reasonable air distribution sheme is prerequisite for controlling concentration of welding soots and producing proper temperature, velocity for welding process in aluminum alloy welding workshop.Therefore, air distribution scheme A and scheme B were proposed for displacement ventilation system in an aluminum alloy welding workshop of an auto manufacturer based on the interior layout of the welding spots at first. In scheme A, two rows of air distribution outlets were installed, one row was along one side of cross and the other was along the safe passage in the middle of the cross of the welding workshop. In scheme B, only one row of air distribution outlets were installed along the side of the cross of the welding workshop, In Scheme A and Scheme B, air inlets were on the ceiling of the workshop. Then the software FLUENT was used to simulate the contaniminant,velocity, temperatrure and pressure field of the workshop with air distribution scheme A and scheme B. It is found that better ventilation effect can be created by using scheme A. And then, air supply flow rate were optimized under scheme A by maintaining air supply temperature constant. It is suggested that the optimal air change rate should be 2 times per hour.