To Multi-obj Ectively Optimize The Airflow Organization Of Displacement Ventilation System Of Welding Plants

Currently, various occupational diseases caused by indoor air pollution frequently, researchers start to strengthen the attention and study to the indoor air quality. Specially about the indoor pollution control in large industrial plant already become a research hotspot. Displacement ventilation system has unique advantages of governing the indoor air pollution for large industrial plants and has been often used in industrial plants.This research, from perspective of multi-objective optimization, combines with the actual situation of welding plant which is with large space to optimally study displacement ventilation airflow.By studying the indoor air evaluation and impact factor, here selected optimized evaluation(indoor air distribution performance index(ADPI), energy utilization factor(η) and uneven temperature distribution coefficient(kt)) and impact factor(air temperature(T), air velocity(u)and solder heat dissipation(Q)) In this paper, multi-objective optimization is: solving the maximum of indoor air distribution performance index and energy utilization factor and theminimum of non-uniform temperature distribution coefficients; The constraint is that air supplying temperature and velocity is as small as possible, while heat pads as large as possible within a reasonable range of values, with other parameters unchanged, the welding plant displacement ventilation system is with the optimal state to calculate the optimum working conditions.In this paper, the relative importance of matrix is adopted to confirm the weights of the evaluation and determine the impact of ranging factors based on the analysis to the plant characteristics. By using the “Design Expert” to design 17 sets of CFD simulation working conditions and then theoretically analysis to the simulation results, the results show that the welding plant formed a clear displacement ventilation airflow in the simulation working condition. After that, in this paper, the experimental study is proceeded by comparative analysis of the numerical simulation values, and that shows the numerical simulation results is consistent with experimental research value. Finally, the data obtained from numerical simulation is used to run the corresponding surface analysis for each index and get the single target quadric equation. By making use of the sub-goals(indicators) weights to sourcing get multi-objective function and then use MATLAB optimization toolbox to solve the objective function and conduct the comparative analysis.In this paper, the optimal solutions of single objective function are worked out as follows: optimal solution for indoor air distribution performance index: T =20.2℃, u=2.93m/ s,2Q =184.56W/ m; Optimal solution for energy efficiency index: T =21.38℃, u=2.11m/ s,2Q =200W/ m; Optimal solution for uneven temperature distribution coefficient index: 2T=21.38℃,u=2.11m/ s,Q=200W/ m.The overall objective function optimal solution: 2T=20.889℃,u=2.011m/ s,Q=105.271W/ m.This paper studies the optimization of both single target and multi-objective for the indoor air-quality. The multi-objective optimization can be used to adjust the working conditions when considering the overall results; When the key target needs to be focused, the single target optimization can be as a reference. Therefore, the research results of this paper could be of some guidance for engineering design.