Optimization Study Of The Filtration Performance Of Pleated Filter Using Response Surface Methodology Based On CFD

It becomes a focus of public concern to filtrate fine particles in dust air effectivelyfor the increasingly severe smog. Currently pleated filter is widely used in air filter andindustrial cartridge filter for its large filtration area, high filtration efficiency and smallvolume. Low resistance, high efficiency and long service life are the targets ofresearchs about pleated filter, and the resistance of pleated filter is mainly affected bythe structural parameters and the properties of filter media, and the service life ismainly affected by the air distribution inside the filter, therefore, the optimization aboutthe structure parameters and air distribution of pleated filter has important theoreticaland practical significance.Based on the structural features of pleated filter, the two-dimensional numericalmodel of plate-shaped pleated filter and cylindrical pleated filter was establishedrespectively using the numerical simulation method, and the calculation model wasvalidated; Then by changing the structure parameters of the model (pleat height, pleatspacing, or outside diameter, number of pleats, pleated height) and operatingconditions (filtration velocity or flow) to analyze the effects of structure parametersand operating conditions on the resistance and air distribution on the basis of responsesurface methodology, and quadratic polynomial prediction models of resistance and airdistribution were established to optimize each factor; This article also tested theresistance and filtration efficiency for5different structural parameters of theplate-shaped pleated filter by experiment, and the experimental results were comparedwith the simulation results. The results showed that:(1)In this paper, the numerical results are in good agreement with the results ofreference, and the error is less than5%, which indicates that the numerical calculationmodel can be used to simulate the resistance and air distribution of pleated filter.(2) For plate-shaped pleated filter, pleated height(h), pleat spacing(W) and filtrationvelocity(Vf) both affect the resistance of the pleated filter, and the impact is significantas Vf> W> h. The resistance increases linearly with the increases of Vf; With theincrease of W, the resistance decreases first and then increases, and there is an optimalW to make the resistance minimize; When Vfis less than a certain value, the resistanceincreases with the increases of h, but when Vfis more than this certain value, theresistance increases with the decreases of h, so there is also an optimal h to make the resistance minimize.(3) Air distribution of the plate-shaped pleated filter is mainly affected by pleatedheight (h) and pleat spacing (W), but the influence of W is more significantly than h. Ash increases, the airflow through the ends of the pleat decreases and the airflow throughthe central region of the pleat increases; The influence of W on the ends are almostconsistent, airflow through the ends increases first and then decreases as the Wincreases, but airflow through the central region has a contrary trend; The changing ofthe filtration velocity(Vf) major affects the ends of the pleat and almost does not affectthe central region, and airflow through the upper region of the pleat increases with theincreases of Vf, but the lower region has a contrary trend.(4) Experiments on5kinds of different structural parameters of plate-shaped pleatedfilter showed that: the impact of pleated height (h), pleat spacing (W) and filtrationvelocity (Vf) on the resistance is agreement with the conclusion obtained by simulation,and when consider resistance only, the optimal structure parameters is h=25mm,W=11mm, which is completely consistent with the result of optimization based on theresponse surface methodology. The filtration efficiency of the pleated filter increases asthe Vfdecreases, but the trend is not very clear; The filtration efficiency decreases asthe h decreases; The influence of W on the filtration efficiency is contrary to theinfluence of h, the W is larger, the efficiency is higher, and the influence of W is greaterthan the influence of h; The influences of each factor on the efficiency and airdistribution are almost consistent, which proved that the optimization of the efficiencycan be described by the optimization of air distribution.(5) Similar to the plate-shaped pleated filter, the resistance of the cylindrical pleatedfilter increases linearly as the operating condition (Q) increases; The resistance will belarge when the outside diameter (D) or the number of pleats (N) is too large or toosmall, and there is an optimal D and N to make the resistance minimize; The pleatheight(h) also has some impact on the resistance, but is not as significant as the other3factors.(6) Air distribution of the cylindrical pleated filter is maily affected by the outsidediameter (D), number of pleats (N) and pleat height (h), the influence of the operatingcondition is not as significant as the other3factors. With the increase of D, the airflowthrough the upper and middle region decrease first and then increase, the fold lowerregion has an opposite trend; The airflow through the upper region increases first andthen decreases as the N increases, and the airflow through the lower region decreases first and then increases, and the influence of N to the upper region is more obviousthan to the lower region, but the airflow through the middle region keeps an increasingtrend; The airflow through the upper and middle region increase as h increases and theairflow through the lower region decreases.(7) In the range of each parameter in this study, when h=55mm, W=14.8485mm,Vf=0.005m/s, the plate-shaped pleated filter has a lower resistance and a more uniformair distribution; And when D=290mm, N=36, h=50mm, Q=0.06m3/s, the cylindricalpleated filter has a lower resistance and a more uniform air distribution.