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NAFA Guide to Air Filtration. Chapter 13 Owning and Operating C ost. Another Approach …. Air Filter Comparison. By Dirk ter Horst April 19 th , 2012. Objective Energy Cost Calculation: 2 approaches Calculation Example & Methodology Comparison Total Filtration Cost Tool’s presentation
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NAFAGuide to Air Filtration. Chapter 13Owning and Operating Cost Another Approach…. Air Filter Comparison By Dirk ter Horst April 19th, 2012
Objective • Energy Cost Calculation: 2 approaches • Calculation Example & Methodology Comparison • Total Filtration Cost Tool’s presentation • Conclusions OUTLINE
Present a practical and easy approach to air filter evaluations + operation based on: • End user/customer experience (Pressure drop and filter life) • Standardized filter life indicator (ASHRAE 52.2 DHC) • All air filtration associated costs • Use of software Objective
NAFA • Customer experience (Pressure drop and Time) • Constant environmental conditions • Average pressure drop • Straight Line • New approach • Customer experience (Pressure drop and time) • Constant environmental conditions • Time vs. Pressure Drop • Time vs. ASHRAE DHC • Air filter Pressure Drop vs. DHC Signature Assumptions and considerations
Considering the pressure drop changes linearly with time the energy consumption is expressed by: Where: ΔP0 = Initial Filter pressure drop [Pa] ΔPf = Final Filter pressure drop[Pa] tf = operating time[hrs] = average pressure drop Linear Pressure Drop Approach
Considering the pressure drop of the filter versus time, the energy consumption is expressed by: Filter Pressure Drop vs. Time Approach
The energy cost is calculated by: • Linear pressure drop vs. time: • Filter pressure drop vs. time: Where: E = energy consumption [kWh] Q = airflow [m3/s] ΔP = pressure Drop across the filter [Pa] t = the time is operating the fan [hrs.] η = system efficiency (fan, motor & drive) [%] Energy Cost
$273/360X365=$277 $301.2/360X365=$305.4 Same results…
This example: Difference/year: $5,863.59 (22.5%) Linear vs DHC curve..For 100 filters
= + Assumption: Air filters of the same efficiency and media type have captured the same amount of dust if they are exposed to identical environmental conditions over the same period of time Transposition…
Filter A: • MERV 14. 24x24x4 Box type. • Initial pressure drop: 0.35 inch H2O • DHC at 1.5” H2O: 67grams. ASHARE Dust • 2000 cfm • $70.0/unit Filter B • MERV 14. 24x24x4 Box type • Initial pressure drop: 0.3 inch H2O • DHC at 1.5” H2O: 143 grams. ASHRAE Dust • 2000 cfm • $70.0/unit Two filters to work with… Example
Two different filters without DHC consideration Linear approach: US$ 701.74/year Two different filters with DHC consideration Linear approach… US$ 9,682,90/year Linear approach… for 100 filters
Two different filters With DHC consideration Curve approach US$ 9,173.82/year Curve approach… for 100 filters
Pressure Drop of filters at change-out time for financial optimization: 0.85inch w.g. Cost reduction: $9,712.03/year (for 100 filters) Optimization Linear approach..
Pressure Drop of filters at change-out time for financial optimization: 0.60inch w.g. Cost reduction: $10,134.13/year (for 100 filters) Optimization… DHC curves.
Filter Type • Filter depth • Frame type • Frame material • Filter media material • Face screen • Incinerable • Filter brand/make • Test standard • Air flow • Maximum final pressure drop • Efficiency • Test dust • Test Laboratory • Test filter procurement/source • Age of test report • UL 900 compliance • Fan type • Reasons for change out time • Other considerations Compare Apples to Apples…
Easy calculation…. Let’s see a software tool: http://filtrationcost.lpdtechnologies.com Practical approach to TFC
Use the ASHRAE 52.2 DHC curve information when evaluating the financial impact of air filters. • Calculate the recommended filter change out pressure drop (optimization). • The cheapest filter nor the filter with the lowest initial pressure drop are necessarily the best solution. • There is a WIN-WIN opportunity for the customers and the industry! Conclusions