Study On Air Distribution Of Displacement Ventilation In Integrated Workshop In Winter

With the development of mechanical manufacturing technology, thewelding technology has been promoted in recently years. A lot of heatand pollutant are produced in the welding process. As heat source andpollutant source both exist, which made welding workshop fittable toapply displacement ventilation system. The displacement ventilationsystem in workshop are often setted on the ground. The fresh air canreplace the polluted air by falling tendency in summer condition, andraised with polluted air. So, Displacement ventilation mode is come upwith summer condition. While in winter condition, there are somecharacteristics in displacement ventilation system: as the supply airtemperature is higher than indoor temperature, the supply air has atendency to rising for the power of heat buoyancy lift, so it is adisadvantage to descend and form displacement ventilation airdistribution. On the other hand, the air volume is a very importantparameters in displacement ventilation design process. To Large integralworkshops, its ventilation mode often adopt large air flow and highvelocity to keep indoor air quality, which lead to energy dissipation andhave disadvantage to form displacement ventilation air distribution.While the supply air have small air flow and low speed,the pollutant cannot be expel in time, which harm the worker health. So, in order toimprove indoor air quality and look for a theoretical foundation to reducethe energy consumption in workshop, it is significance to researchdisplacement ventilation air distribution in winter condition.In order to study whether displacement ventilation system can formair distribution of displacement ventilation in winter and influence factorof air distribution.In the study, Computational Fluid Dynamics methodsis taken to research displacement ventilation in integrated workshop inwinter. The contents include: the set of angles of supply air, thereasonable design of supply air flow and the influence of smoke screen.Firstly, Compared with indoor air distribution and air age with anglesbetween horizontal plane and flow surface (be short for angle of supply)of0°,15°,30°,45°,60°,75°, results shows that with the angles of airflow0°, the air distribution of displacement ventilation can not beformed in winter condition as the supply air can not reach the bottom ofthe workshop, and with the angles of airflow45°, the air distribution ofdisplacement ventilation can be formed and in the angles of airflow, theventilation efficiency is the best in simulation conditions. Secondly,simulation method is carried out in ten kinds of airflow, include0.1Q～Q(Q is airflow calculated by dilution ventilation method),and studyventilation efficiency with airflow increased, results show that airflowexceeds to0.3Q, ventilation efficiency increase slowly with airflow rising,in the terms of ensuring ventilation efficiency, airflow need not too big.So, airflow of displacement ventilation system with60%airflow ofdilution ventilation can be the minimum airflow which ensure the airquality of breathing zone. Finally, simulation two conditions in weldingworkshop, the one is set smoke screen, the other is not set, compared theair distribution and air age in workshop with the two conditions, resultshows that with the smoke screen, ventilation efficiency reduced, andincrease the energy consumption of the system, but can improve the airquality in the workshop.A verified experiment is carried out in a welding workshop withdisplacement ventilation. The temperature data and velocity data aremeasured. Compared the numerical simulation results with experimentresults, found the experiment results have the same tendency tosimulation results. So, it is feasible that adopt CFD methods to researchthe air distribution in integral welding workshop. The conclusions couldbe used to guide engineering design.