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Filter Rating. Definition: System of classification according to merit or amount Assessment of something in terms of quality, quantity or both What filter parameters should be included? Filter Performance – pressure drop, efficiency, life Energy Perceive Value Cost. Filter Rating.
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Filter Rating Definition: • System of classification according to merit or amount • Assessment of something in terms of quality, quantity or both • What filter parameters should be included? • Filter Performance – pressure drop, efficiency, life • Energy • Perceive Value • Cost
Filter Rating • Is it possible to combine filter performance characteristics into one criterion? • Greater value of the criterion equal to “better” filter • Traditional quality factor (figure of merit): • E – filter efficiency and ΔPo – filter pressure drop • Potential issues: • Different ΔPo units • Results at different flow rate
Filter Rating • Example 1: E1 = 80% and ΔPo = 0.40” H2O α1 = - ln (1 – 0.8)/ 0.40 = 1.609/0.40 = 4.02 • Example 2: E1 = 80% and ΔPo = 0.30” H2O α2 = - ln (1 – 0.8)/ 0.30 = 1.609/0.30 = 5.36 • Example 3: E1 = 85% and ΔPo = 0.40” H2O α2 = - ln (1 – 0.85)/ 0.40 = 1.897/0.40 = 4.74
Filter Rating • Single Aggregate Objective Function (AOF) • Weighting method, linear AOF: MAX • E – filter efficiency; ΔPo – filter pressure drop • C – filter cost; DHC – filter dust holding capacity • λ – weighting factors; ∑ λi = λ1 + λ2 + λ3 + λ4=1 • λ – weighting factors are assigned based on priority - subjective
Filter Rating • Combination of objectives: • Other objectives: Cost, Energy
Filter Rating - Examples • MERV – is MERV a rating system? • Residential filters – Home Depot • FPR (Filter Performance Rating) = 1 – 10 scale Weighted Average = λ1(Efficiency Large Particles) + λ2(Efficiency Small Particles) + λ3 DHC λ1 + λ2 + λ3 = 0.6 + 0.3 + 0.1 =1 • FPR = 10 for Weighted Average > 25 • Residential filters – 3M • MPR – Microparticle Performance Rating ability to capture particles 0.3 – 10 µm (E1)