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Delivering Sustainability Promise to HVAC Air Filtration

Delivering Sustainability Promise to HVAC Air Filtration. Dr. Christine Sun and Dan Woodman Freudenberg Filtration Technologies, L.P. Hopkinsville, KY42240, USA. 2009 NAFA Annual Convention Sep. 16-18, 2009, Toronto, Canada. Outlines. What is sustainability? How to evaluate sustainability

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Delivering Sustainability Promise to HVAC Air Filtration

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  1. Delivering Sustainability Promise to HVAC Air Filtration Dr. Christine Sun and Dan Woodman Freudenberg Filtration Technologies, L.P. Hopkinsville, KY42240, USA 2009 NAFA Annual Convention Sep. 16-18, 2009, Toronto, Canada

  2. Outlines • What is sustainability? • How to evaluate sustainability • Classification of energy efficiency • Bernoulli’s equation • Wattage method • Pressure drop & new exponential model • Energy efficient air filter • Life cycle cost analysis

  3. What is sustainability? • “Development that meets the needs of the present without compromising the ability of future generations to meet their own needs” —1987 United Nation’s Brundtland Commission • “Sustainability for ASHRAE means energy efficiency and healthy, productive indoor environments” — William Harrison, 2008-2009 ASHRAE President

  4. How to evaluate sustainability • Clean and healthy air • Filtration efficiency • ASHRAE 52.2-2007 • EN779: 2002 • Energy efficiency • Currently no standardized method in the industry to classify filters’ energy efficiency. Need to develop.

  5. Energy consumption for air filters • 15-20% of the total electrical energy consumption is used by fans in air handling units. • Approximately 1/3 of that is related to pressure loss of air filters. • One year at fixed volumetric flow rate of 2000 CFM a filter with an average pressure loss of 0.4” WC requires 1250 kWh if the fan efficiency is set to 70%. • The energy cost is generally greater than the filter cost, and pressure loss reduction becomes increasingly significant for energy reductions. • Lower pressure loss by 10 Pa means 125 kWh less energy in this example. Energy efficient air filters can save energy Current air filter classification does not consider energy efficient operation.

  6. Energy rating options How Should We Classify Industrial Air Filters For Energy Usage? Marketing Program Technical Standards Combined Attributes Energy Stand Alone Energy Star • Set Guidelines • Awards Recognition for Products that Meets Guidelines Wattage KEP ECI • Defines a Single Scientifically Based Energy Measurement • Combines Efficiency and Energy Consumption into One Metric

  7. Energy Star Marketing Program How Should We Classify Industrial Air Filters For Energy Usage? • Marketing incentive program backed by the EPA to help consumers identify energy efficient products • Product standards are set by product categories • No product category exists for filters • Product category for room air cleaners: • Qualified models must meet minimum ratio of clean air delivered for each watt of energy (CADR/Watt >2) • Secondary features must meet energy efficiency requirements in standby mode. Technical Standards Combined Attributes Energy Stand Alone Energy Star • Set Guidelines • Awards Recognition for Products that Meets Guidelines Wattage KEP ECI • Defines a Single Scientifically Based Energy Measurement • Combines Efficiency and Energy Consumption into One Metric

  8. 3. Calculate the kep number C = empirical constant; (here C = 22 Pa) Key Energy Performance (KEP) Combined Attributes Technical Standards How Should We Classify Industrial Air Filters For Energy Usage? • Proposed as a technical standard in Europe 1. Determine average pressure drop from AC Fine dust loading Marketing Program Energy Stand Alone 2. Determine the average efficiency according to EN 779 from ASHRAE dust loading Energy Star 4. Classify Wattage KEP ECI

  9. Energy Cost Index (ECI) Combined Attributes Technical Standards How Should We Classify Industrial Air Filters For Energy Usage? • Proposed as a technical standard in Europe, currently used for marketing in US by a manufacturer • Uses artificially treated filter efficiency and basic energy cost to develop ratio of cost per efficiency. • KwH = 0.746*HP*Hours & *Assuming 10 cent per KwH and 60% fan efficiency • Converts ratio by filter construction type in to 5 star rating scheme. Marketing Program Energy Stand Alone Energy Star • Set Guidelines • Awards Recognition for Products that Meets Guidelines Wattage KEP ECI • Defines a Single Scientifically Based Energy Measurement • Combines Efficiency and Energy Consumption into One Metric

  10. Wattage Rating Energy Stand Alone Technical Standards How Should We Classify Industrial Air Filters For Energy Usage? • All rating systems need to determine ΔP to derive energy. • This method uses scientifically correlated method to determine lifetime average ΔP. • Rating system evaluated energy efficiency independent from efficiency. • Intuitive understanding of energy consumption by consumer (Watts) Marketing Program Combined Attributes Energy Star • Set Guidelines • Awards Recognition for Products that Meets Guidelines Wattage KEP ECI • Defines a Single Scientifically Based Energy Measurement • Combines Efficiency and Energy Consumption into One Metric

  11. Understanding of energy used to run a filter Bernoulli’s equation (Energy Conservation) Airflow 1 2 ?

  12. Energy loss over filter + Understanding of energy used to run a filter Bernoulli’s equation (Energy Conservation) Airflow 1 2

  13. Energy loss over filter/m3 + Energy used to run air through the filter Airflow 1 2 As V1=V2, Z1=Z2, therefore, Energy Loss over filter/m3 =P1-P2=ΔP

  14. Energy used to run air through the filter Considering airflow through the filter as Q and system efficiency η (0-1), then E: energy in kWh; Q: airflow rate in m3/s ΔP: pressure drop in Pa η: system efficiency (0-1) t: operation time (hr)

  15. Energy eff. classification — Wattage Energy in wattage used to run air through the filter: W: power (Watt) v: face velocity (m/s) A: face area(m2)

  16. Energy eff. classification — Wattage (Cont.) For standard test duct, 24”x24” duct, v = 2.5 m/s, and η = 70%

  17. Average pressure drop

  18. Average pressure drop models Arithmetic: Geometric: Integral:

  19. Actual pressure drop vs. dust loading

  20. New exponential model developed based on actual loading curves according Ashrae 52.2 a and b: constants of filters x: loaded dust (g) Exponential pressure drop model

  21. Pressure drop model

  22. Comparison of pressure drop models

  23. Comparison of pressure drop models

  24. Average pressure drop Exponential Model:

  25. Filer energy efficiency — Wattage Directly use wattage to run the air through the filter to classify filter energy efficiency

  26. Filter energy efficiency class *Round to 10

  27. Energy efficient air filter — I • Electret enhancement Electrostatic Attraction Inertial Impaction (-) (+) Filter Fiber Brownian Diffusion Interception Mechanical Filter + e-Charge = Electret Filter

  28. Filter media energy efficiency *GF — glass fiber, **electret media Tested by TSI8130 @ 48l/min using NaCl aerosol

  29. Energy efficient air filter — II + gradient media structure Nano fiber

  30. Life cycle cost (LCC) analysis Looking at total cost throughout filter service life: Filter cost (LCCFilter) Energy cost (LCCEngr) Maintenance cost (LCCMaint) Disposal cost (LCCdisp) Freight cost (LCCfreight) Miscellaneous cost (LCCMisc.) LCC = LCCfilter+ LCCengr + LCCmisc

  31. Life cycle cost analysis — I Operation data in a general air make up unit

  32. Life cycle cost analysis — II Data from a real AHU CO2 emission reduction: 40.1 ton/yr

  33. Surface-loading Total $27,550.12 Life cycle cost share $720.005.2% Depth loading Total $13,923.32 42.4%$5,880.00 52.4%$7,323.32 $1,956.007.1% $4,160.0015.1% 77.8%$21,434.12

  34. Summary • Energy efficiency is a critical value to evaluate filters’ sustainability besides filtration efficiency. • Wattage provides a direct and scientific method to classify filter’s energy efficiency. • New exponential model showed excellent consistence to reflect actual pressure drop vs. dust loading. • Life cycle cost analysis is a useful tool to evaluate the sustainability of air handling units. • Energy use is a primary cost over filter service life, followed by filter cost and miscellaneous cost (incl. maint., freight, and disposal).

  35. Thanks for your attention! Let’s work together for a sustainable and healthy environment Dr. Christine Sun and Dan WoodmanFreudenberg Filtration Technologies, L.P. christine.sun@freudenberg-filter.com (270) 887-5148

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