Kasper De Mulder

New PM control technologies for

indoor PM control

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Outline

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What is PM? • Definition • Sources • Consequences

How to control indoor PM? • Introduction • Study on air cleaning technologies • Mechanical filtration • Electrostatic precipitation • Bipolar air ionization • Performance measurement • Combined technologies

What is PM?

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What is PM? – definition

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Airborne particulate matter (PM) = small solid particles and liquid droplets dispersed in our environment

Suspended Particulate Matter (SPM) or Total Suspended Particles (TSP) : da < 100μm

Inhalable Particles (namely PM10) : da < 10μm

Fine Particles (namely PM2.5) : da < 2.5μm

Source: Yao Q., Li S.-Q., Xu H.-W., Zhuo J.-K., Song Q. (26-09-2010). “Reprint of: Studies on formation and control of combustion particulate matter in China: A review”

What is PM? – definition

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Size distribution [μm] of PM

Various types of airborne particles

Source: Jisaac9 (30-09-2010). "Airborne particles are commonly either biological contaminants, particulate contaminants, gaseous contaminants, or dust.". (25-10-2013) https://upload.wikimedia.org/wikipedia/commons/4/47/Airborne-particulate-size-chart.jpg

What is PM? – sources

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Outdoor polluted air goes inside

Indoor pollution sources

E.g. Candle burning, onion frying, incense stick burning, smoking, hair spraying, hair drying, vacuuming & boiling

Mean values

Source: Glytsos T., Ondrácek J., Dzumbová L., Kopanakis I., Lazaridis M. (11-01-2010). "Characterization of particulate matter concentrations during controlled indoor activities"

What is PM? – sources

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Measured size distributions with model results.

Source: Glytsos T., Ondrácek J., Dzumbová L., Kopanakis I., Lazaridis M. (11-01-2010). "Characterization of particulate matter concentrations during controlled indoor activities“

What is PM? – consequences

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Impact on human health, visibility, local meteorology, climate change, … (cf. previous presentations)

Sick Building Syndrome (SBS) due to bad indoor air quality

Typical for PM pollution: respiratory symptoms such as wheezing and coughing

Control of indoor PM is important in order to prevent/reduce these consequences

How to control indoor PM?

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How to control indoor PM? – introduction

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Source control: eliminate source or reduce emission

Most effective strategy

Ventilation: exchange air between inside and outside General ventilation: by way of infiltration, natural – or

mechanical ventilation Localized ventilation: by way of exhaust fans

Should be evaluated carefully where there

may be outdoor sources of pollutants

Air cleaning: several technologies available

Widest applied technique for particle removal. Should be combined by either method, no substitute!

Source: United States Environmental Protection Agency (August 2009). "Residential Air Cleaners 2nd edition"

How to control indoor PM? – introduction

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Source control

E.g. smoke outside, adjust combustion appliances, …

Ventilation

General ventilation

Localized ventilation

E.g. new homes can be equipped with HVAC system to bring outdoor air into the home, …

Air cleaning

E.g. local air purifiers, integrated in a HVAC system, …

Source: United States Environmental Protection Agency (August 2009). "Residential Air Cleaners 2nd edition"

How to control indoor PM? – Study on air cleaning technologies

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Study: >250 peer-reviewed papers, conference papers & technical reports on modern air cleaning methods

Result: several kinds of classification of air cleaning technologies Functional principle: physical, physicochemical- & electronic

processes (+variations thereof)

Contaminant(s) being treated: filtration (PMx & microbial), electrostatic precipitation (PMx & microbial), reaction with charged species (PMx & VOCs*), sorption onto solid sorbents (VOCs) & reaction with oxygen species (VOCs)

Local or central

* Volatile organic compounds

Source: Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency"

How to control indoor PM? – Study on air cleaning technologies

13 Source: Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency"

How to control indoor PM? – Study on air cleaning technologies

14 Source: Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency"

How to control indoor PM? – mechanical filtration

15 Source: Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency“

How to control indoor PM? – mechanical filtration

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Most common and most mature technology for PM control

Both central (HVAC) systems and stand-alone fan-filter units

Particles collected due to sticking or electrostatic charge

Higher efficiency implies higher pressure drop higher energy cost for fans

Replace filters frequently due to lowered air quality & increased pressure drop

Source: United States Environmental Protection Agency (August 2009). "Residential Air Cleaners 2nd edition"

How to control indoor PM? – mechanical filtration

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Two major types:

Flat or Panel filters: e.g. glass fibers, animal hair, synthetic fibers, wool, electret, …

Pleated or extended surface filter: generally more efficient, increased surface area, reduced air velocity & smaller fibers. E.g. fiber mats, bonded glass fibers, synthetic fibers, …

High efficiency particulate air

(HEPA) filters are a type of extended surface filter:

Removes 99.97% of particles with da ≥ 0.4μm (of passing air)

Three mechanisms: interception, impact & diffusion

Source: LadyofHats (13-08-2008). "Diagram showing the main parts of a HEPA filter on the large diagram". (25-08-2013) https://upload.wikimedia.org/wikipedia/commons/b/b1/HEPA_Filter_diagram_en.svg

How to control indoor PM? – electrostatic precipitation

18 Source: Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency"

How to control indoor PM? – electrostatic precipitation

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Most common electric air cleaner

Both central (HVAC) systems and stand-alone fan-filter units

Two major types: One-stage (top figure): less

expensive but also less effective

Two-stage (lower figure): separate ionization section and collecting plate section. Minimizes ozone production

Charged particles supplied to indoor air are potential health risk

Cleaning the collector plates is essential to maintaining adequate performance.

Sources: 1. Air Clean Co. "Single stage air clean ESP". (25-10-2013) http://www.aircleancompany.com/Air_Clean_ESP_files/image015.jpg 2. Mason E. (18-07-2012). "The electrostatic precipitator". (25-08-2013) https://upload.wikimedia.org/wikipedia/commons/5/52/Electrostatic_precipitator.svg

How to control indoor PM? – bipolar air ionization

20 Source: Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency“

How to control indoor PM? – bipolar air ionization

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Simplest electric air cleaner

Mostly stand-alone fan-filter units in the form of tabletop, portable and ceiling mounted units

Like ESPs risk of ozone generation. No proof of effect on SBS

Ionized particles hold to nearby surfaces e.g. walls, furniture, … or combine with other particles and settle on room surfaces

Source: Gorczyca J., Jacobs M., Kowalski N., Rodrigo R.D. (31-08-2004). "Foraminous filter for use in air ionizer". (25-10-2013) http://www.freepatentsonline.com/6785114-0-large.jpg

How to control indoor PM? – Performance measurement

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Portable air cleaners: CADR* ratings developed by AHAM** CADR is a measurement that

symbolizes the amount of polluted air that would be replaced by the same amount of clean air each minute

It allows you to compare different kinds of devices/brands

AHAM provides a complete listing of all certified cleaners with their CADR values at www.cadr.org

* Clean air delivery rate

** Association of Home Appliance Manufacturers . Recognised by Environmental Protection Agency as an official certification body

Source: AHAM (2005). “AHAM verifide”. (25-10-2013) http://ahamverifide.org/search-for-products/room-air-cleaners/

How to control indoor PM? – Performance measurement

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Mechanical air filter: MERV* ratings (ranging from 1 to 20) developed by ASHRAE** Flat or penal air filter: MERV of 1 to 4 mostly used to protect

HVAC equipment

Pleated or extended surface filters: medium efficiency filters with MERV of 5 to 13, high efficiency filters with MERV of 14 to 16 and HEPA filters with MERV of 17 to 20 Filters with a MERV between 7 and 13 are likely to be nearly as effective as true HEPA filters

Electric air cleaners: no standard measurement. May remove small particles, but may be ineffective in removing

large particles.

Electronic air cleaners can produce ozone—a lung irritant

* Minimum Efficiency Reporting Value

**American Society of Heating, Refrigerating and Air-Conditioning Engineers

Sources: United States Environmental Protection Agency (August 2009). "Residential Air Cleaners 2nd edition“ Kadribegovic R., Ekberg L., Fahlén P. (22-08-2008). "Air cleaning technologies – Function requirements and energy efficiency“

How to control indoor PM? – combined technologies

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Improved air cleaning due to combination of different technologies: Pre-filter: largest particles HEPA filter: dust, allergens and

other solid particles (including bacteria)

Carbon filter: odors, VOCs and chemicals that other filters cannot filter

Photocatalytic Oxidation Filter: chemical molecules, bacteria and odor-causing compounds

UV Lamp: micro-organisms, such as germs, viruses, fungi (such as mold) and bacteria

Ionizer: floating pollutants such as dust, bacteria, etc

Source: Carol A. James (18-08-2012). "How the Surround S5000 Works". (25-10-2013) http://www.inspiredliving.com/surround-air-ionizers/images/s5000-how-it-works.jpg

Questions?

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