Evaluation of different discharging methods on HVAC electret filter media

Min Tang; Drew Thompson; Sheng Chieh Chen; Yun Liang; David Y Pui

doi:10.1016/j.buildenv.2018.05.048

Evaluation of different discharging methods on HVAC electret filter media

Min Tang, Drew Thompson, Sheng Chieh Chen, Yun Liang, David Y Pui

Mechanical Engineering

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

Electret filters with electrostatic charges added on fibers are widely used in HVAC system of residential and commercial buildings to mitigate PM_2.5 exposure in indoor environments. Filtration applications require the knowledge of minimum filtration efficiency of electret filters under worst condition. To determine the minimum efficiency, different electret discharging methods are used in test standards to eliminate electrostatic effects. This study evaluated the isopropanol (IPA) liquid discharging method in EN 779 and the IPA saturated vapor treatment in ISO 16890. It was found that although both IPA liquid immersion and saturated vapor treatment can significantly remove fiber charge, saturated vapor treatment showed better discharging performance. The charge density of media discharged by IPA liquid immersion and saturated vapor treatment were 2 μC/m² and 0 μC/m², respectively. It demonstrated that IPA saturated vapor treatment can completely remove fiber charge, while undesirable fiber charge occurred after being treated by IPA liquid due to interface electrification. The test results of unsaturated vapor treatment indicated that IPA in the phase of vapor was not capable of removing fiber charges. The fact that saturated vapor treatment was more effective than liquid immersion was due to the different discharging process. For saturated vapor treatment, vapor condensed on fiber surface and formed a liquid layer with thickness of 15 nm. This ultra-thin layer of IPA liquid can discharge the fiber charge completely without inducing extra charge after liquid evaporation. This study concluded that discharging method in ISO 16890 should be used in electret filter test.

Original language	English (US)
Pages (from-to)	206-214
Number of pages	9
Journal	Building and Environment
Volume	141
DOIs	https://doi.org/10.1016/j.buildenv.2018.05.048
State	Published - Aug 15 2018

Bibliographical note

Funding Information:
The authors thank the support of members of the Center for Filtration Research: 3M Corporation , A.O. Smith Company , Applied Materials Inc. , BASF Corporation , Boeing Company , Corning Co. , China Yancheng Environmental Protection Science and Technology City , Cummins Filtration Inc. , Donaldson Company, Inc. , Entegris, Inc. , Ford Motor Company , Guangxi Wat Yuan Filtration System Co., Ltd , MSP Corporation ; Samsung Electronics Co., Ltd. , Xinxiang Shengda Filtration Technology Co.,Ltd. , TSI Inc. , W. L. Gore & Associates, Inc. , Shigematsu Works Co., Ltd. , and the affiliate member National Institute for Occupational Safety and Health (NIOSH) . Parts of this work were carried out in the Minnesota Nano Center that receives partial support from NSF through the NNIN program. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program.

Funding Information:
The authors thank the support of members of the Center for Filtration Research: 3M Corporation, A.O. Smith Company, Applied Materials Inc., BASF Corporation, Boeing Company, Corning Co., China Yancheng Environmental Protection Science and Technology City, Cummins Filtration Inc., Donaldson Company, Inc., Entegris, Inc., Ford Motor Company, Guangxi Wat Yuan Filtration System Co., Ltd, MSP Corporation; Samsung Electronics Co., Ltd., Xinxiang Shengda Filtration Technology Co.,Ltd., TSI Inc., W. L. Gore & Associates, Inc., Shigematsu Works Co., Ltd., and the affiliate member National Institute for Occupational Safety and Health (NIOSH). Parts of this work were carried out in the Minnesota Nano Center that receives partial support from NSF through the NNIN program. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program.

Publisher Copyright:
© 2018 Elsevier Ltd

Keywords

Discharging
Electret filter
Filtration
HVAC
Isopropanol
Particle

Publisher link

10.1016/j.buildenv.2018.05.048

Find It

Find It at U of M Libraries

Cite this

@article{bd7e00e4c829458da07e4932d9c9fcac,

title = "Evaluation of different discharging methods on HVAC electret filter media",

abstract = "Electret filters with electrostatic charges added on fibers are widely used in HVAC system of residential and commercial buildings to mitigate PM2.5 exposure in indoor environments. Filtration applications require the knowledge of minimum filtration efficiency of electret filters under worst condition. To determine the minimum efficiency, different electret discharging methods are used in test standards to eliminate electrostatic effects. This study evaluated the isopropanol (IPA) liquid discharging method in EN 779 and the IPA saturated vapor treatment in ISO 16890. It was found that although both IPA liquid immersion and saturated vapor treatment can significantly remove fiber charge, saturated vapor treatment showed better discharging performance. The charge density of media discharged by IPA liquid immersion and saturated vapor treatment were 2 μC/m2 and 0 μC/m2, respectively. It demonstrated that IPA saturated vapor treatment can completely remove fiber charge, while undesirable fiber charge occurred after being treated by IPA liquid due to interface electrification. The test results of unsaturated vapor treatment indicated that IPA in the phase of vapor was not capable of removing fiber charges. The fact that saturated vapor treatment was more effective than liquid immersion was due to the different discharging process. For saturated vapor treatment, vapor condensed on fiber surface and formed a liquid layer with thickness of 15 nm. This ultra-thin layer of IPA liquid can discharge the fiber charge completely without inducing extra charge after liquid evaporation. This study concluded that discharging method in ISO 16890 should be used in electret filter test.",

keywords = "Discharging, Electret filter, Filtration, HVAC, Isopropanol, Particle",

author = "Min Tang and Drew Thompson and Chen, {Sheng Chieh} and Yun Liang and Pui, {David Y}",

note = "Funding Information: The authors thank the support of members of the Center for Filtration Research: 3M Corporation , A.O. Smith Company , Applied Materials Inc. , BASF Corporation , Boeing Company , Corning Co. , China Yancheng Environmental Protection Science and Technology City , Cummins Filtration Inc. , Donaldson Company, Inc. , Entegris, Inc. , Ford Motor Company , Guangxi Wat Yuan Filtration System Co., Ltd , MSP Corporation ; Samsung Electronics Co., Ltd. , Xinxiang Shengda Filtration Technology Co.,Ltd. , TSI Inc. , W. L. Gore & Associates, Inc. , Shigematsu Works Co., Ltd. , and the affiliate member National Institute for Occupational Safety and Health (NIOSH) . Parts of this work were carried out in the Minnesota Nano Center that receives partial support from NSF through the NNIN program. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Funding Information: The authors thank the support of members of the Center for Filtration Research: 3M Corporation, A.O. Smith Company, Applied Materials Inc., BASF Corporation, Boeing Company, Corning Co., China Yancheng Environmental Protection Science and Technology City, Cummins Filtration Inc., Donaldson Company, Inc., Entegris, Inc., Ford Motor Company, Guangxi Wat Yuan Filtration System Co., Ltd, MSP Corporation; Samsung Electronics Co., Ltd., Xinxiang Shengda Filtration Technology Co.,Ltd., TSI Inc., W. L. Gore & Associates, Inc., Shigematsu Works Co., Ltd., and the affiliate member National Institute for Occupational Safety and Health (NIOSH). Parts of this work were carried out in the Minnesota Nano Center that receives partial support from NSF through the NNIN program. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Publisher Copyright: {\textcopyright} 2018 Elsevier Ltd",

year = "2018",

month = aug,

day = "15",

doi = "10.1016/j.buildenv.2018.05.048",

language = "English (US)",

volume = "141",

pages = "206--214",

journal = "Building and Environment",

issn = "0360-1323",

publisher = "Elsevier BV",

}

TY - JOUR

T1 - Evaluation of different discharging methods on HVAC electret filter media

AU - Tang, Min

AU - Thompson, Drew

AU - Chen, Sheng Chieh

AU - Liang, Yun

AU - Pui, David Y

N1 - Funding Information: The authors thank the support of members of the Center for Filtration Research: 3M Corporation , A.O. Smith Company , Applied Materials Inc. , BASF Corporation , Boeing Company , Corning Co. , China Yancheng Environmental Protection Science and Technology City , Cummins Filtration Inc. , Donaldson Company, Inc. , Entegris, Inc. , Ford Motor Company , Guangxi Wat Yuan Filtration System Co., Ltd , MSP Corporation ; Samsung Electronics Co., Ltd. , Xinxiang Shengda Filtration Technology Co.,Ltd. , TSI Inc. , W. L. Gore & Associates, Inc. , Shigematsu Works Co., Ltd. , and the affiliate member National Institute for Occupational Safety and Health (NIOSH) . Parts of this work were carried out in the Minnesota Nano Center that receives partial support from NSF through the NNIN program. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Funding Information: The authors thank the support of members of the Center for Filtration Research: 3M Corporation, A.O. Smith Company, Applied Materials Inc., BASF Corporation, Boeing Company, Corning Co., China Yancheng Environmental Protection Science and Technology City, Cummins Filtration Inc., Donaldson Company, Inc., Entegris, Inc., Ford Motor Company, Guangxi Wat Yuan Filtration System Co., Ltd, MSP Corporation; Samsung Electronics Co., Ltd., Xinxiang Shengda Filtration Technology Co.,Ltd., TSI Inc., W. L. Gore & Associates, Inc., Shigematsu Works Co., Ltd., and the affiliate member National Institute for Occupational Safety and Health (NIOSH). Parts of this work were carried out in the Minnesota Nano Center that receives partial support from NSF through the NNIN program. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Publisher Copyright: © 2018 Elsevier Ltd

PY - 2018/8/15

Y1 - 2018/8/15

N2 - Electret filters with electrostatic charges added on fibers are widely used in HVAC system of residential and commercial buildings to mitigate PM2.5 exposure in indoor environments. Filtration applications require the knowledge of minimum filtration efficiency of electret filters under worst condition. To determine the minimum efficiency, different electret discharging methods are used in test standards to eliminate electrostatic effects. This study evaluated the isopropanol (IPA) liquid discharging method in EN 779 and the IPA saturated vapor treatment in ISO 16890. It was found that although both IPA liquid immersion and saturated vapor treatment can significantly remove fiber charge, saturated vapor treatment showed better discharging performance. The charge density of media discharged by IPA liquid immersion and saturated vapor treatment were 2 μC/m2 and 0 μC/m2, respectively. It demonstrated that IPA saturated vapor treatment can completely remove fiber charge, while undesirable fiber charge occurred after being treated by IPA liquid due to interface electrification. The test results of unsaturated vapor treatment indicated that IPA in the phase of vapor was not capable of removing fiber charges. The fact that saturated vapor treatment was more effective than liquid immersion was due to the different discharging process. For saturated vapor treatment, vapor condensed on fiber surface and formed a liquid layer with thickness of 15 nm. This ultra-thin layer of IPA liquid can discharge the fiber charge completely without inducing extra charge after liquid evaporation. This study concluded that discharging method in ISO 16890 should be used in electret filter test.

AB - Electret filters with electrostatic charges added on fibers are widely used in HVAC system of residential and commercial buildings to mitigate PM2.5 exposure in indoor environments. Filtration applications require the knowledge of minimum filtration efficiency of electret filters under worst condition. To determine the minimum efficiency, different electret discharging methods are used in test standards to eliminate electrostatic effects. This study evaluated the isopropanol (IPA) liquid discharging method in EN 779 and the IPA saturated vapor treatment in ISO 16890. It was found that although both IPA liquid immersion and saturated vapor treatment can significantly remove fiber charge, saturated vapor treatment showed better discharging performance. The charge density of media discharged by IPA liquid immersion and saturated vapor treatment were 2 μC/m2 and 0 μC/m2, respectively. It demonstrated that IPA saturated vapor treatment can completely remove fiber charge, while undesirable fiber charge occurred after being treated by IPA liquid due to interface electrification. The test results of unsaturated vapor treatment indicated that IPA in the phase of vapor was not capable of removing fiber charges. The fact that saturated vapor treatment was more effective than liquid immersion was due to the different discharging process. For saturated vapor treatment, vapor condensed on fiber surface and formed a liquid layer with thickness of 15 nm. This ultra-thin layer of IPA liquid can discharge the fiber charge completely without inducing extra charge after liquid evaporation. This study concluded that discharging method in ISO 16890 should be used in electret filter test.

KW - Discharging

KW - Electret filter

KW - Filtration

KW - HVAC

KW - Isopropanol

KW - Particle

UR - http://www.scopus.com/inward/record.url?scp=85047999078&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85047999078&partnerID=8YFLogxK

U2 - 10.1016/j.buildenv.2018.05.048

DO - 10.1016/j.buildenv.2018.05.048

M3 - Article

AN - SCOPUS:85047999078

SN - 0360-1323

VL - 141

SP - 206

EP - 214

JO - Building and Environment

JF - Building and Environment

ER -

Evaluation of different discharging methods on HVAC electret filter media

Abstract

Bibliographical note

Keywords

Publisher link

Find It

Other files and links

Fingerprint

Cite this