MMEA Project Measuring the filtration efficiency and particle indoor/outdoor concentration ratio Aimo Taipale, Tapio Kalliohaka, Hannu Salmela, Jari Kataja and Matti Niemeläinen VTT Technical Research Centre of Finland

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VTT Clean Air Solutions

§ Active research areas § Fine particle exposure control § Electrical air filtration technologies §  Improving the indoor air quality (IAQ) and building protection § Automotive cabin air filtration § Power plant combustion air filtration § Clean production systems

§ 研究热点 § 颗粒物暴露控制 § 空气电子过滤技术 § 室内空气品质与建筑的保护 § 汽⻋车⻋车内空气过滤 § 发电厂燃烧空气过滤 § 清洁生产制度

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Introduction

§ Improving the indoor air quality (IAQ) is considered to be one of the most efficient way to enhance people´s health and wellbeing in terms of reducing human exposure to fine particles (PM 2.5).

§ The indoor concentration is affected mainly by § Outdoor concentration § Efficiency of supply air filtration § Leakage of the building envelope § Air exchange rate § Indoor sources § Using of room air cleaners

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VTT´s test system in Beijing in the Finnish Embassy residence building

§  Indoor air measurement system was installed in an air handling unit (AHU) in the residence of the Finnish Embassy in October 2014

§ Measurement devices: § Optical particle counter Met One 237 B: Single particles from 0.3 µm § Aerosol photometer TSI Dust Trak: Total mass concentration § Pegasor PPS § Vaisala temperature, humidity and CO2 sensors

§ Four sampling points: § Outdoor air § Mixed air (upstream of the filter) § Supply air (Downstream of the filter) § Return air (average indoor air)

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Measuring principle of air handling unit (AHU)

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User interface of the measuring system

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Filtration set-up in AHU 4: Normal filters

Normal filter set-up consist of Coarse pre-filters (right side) and F7 glassfibre bag filters (left side). Pressure drop of the filter set-up was 60 Pa

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Filtration set-up in AHU 4: Electret filters

In electret filter set-up pre-filters were replaced with corona wire charger and bag filters with LIFA 3G electret filters. Pressure drop was 30 Pa

Wire charger assembly: 6.8 kV and 1.18 mA

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Results

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Particle mass concentration (relative)(normal filters)

21.10. 22.10. 23.10. 24.10. 25.10. 26.10. 27.10. 28.10. 29.10. 30.10.

10

20

30

40

50

60

70

80

90

100

Date

Rela

tive

mas

s co

ncen

tratio

n (%

)

DT OUTDT RETDT MIXDT FILT

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Filtration efficiency and I/O ratio vs. time (normal filters)

21.10. 22.10. 23.10. 24.10. 25.10. 26.10. 27.10. 28.10. 29.10. 30.10.0

50

100Ef

ficie

ncy

(%)

21.10. 22.10. 23.10. 24.10. 25.10. 26.10. 27.10. 28.10. 29.10. 30.10.0

0.5

1

1.5

2

I/O R

atio

Date

0,390,590,841,413,16

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Filtration efficiency and I/O ratio vs. time (electret filters)

03.02. 04.02. 05.02. 06.02. 07.02. 08.02. 09.02. 10.02. 11.02.0

50

100Ef

ficie

ncy

(%)

03.02. 04.02. 05.02. 06.02. 07.02. 08.02. 09.02. 10.02. 11.02.0

0.5

1

1.5

2

I/O R

atio

Date

0,390,590,841,413,16

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CO2 concentration

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I/O ratio and outdoor PM10 concentration

0  

100  

200  

300  

400  

500  

600  

700  

800  

0.00E+00  

2.00E-­‐01  

4.00E-­‐01  

6.00E-­‐01  

8.00E-­‐01  

1.00E+00  

1.20E+00  

2/2/2015  5:44  

2/2/2015  10:58  

2/2/2015  16:13  

2/2/2015  21:27  

2/3/2015  2:41  

2/3/2015  7:56  

2/3/2015  13:10  

2/3/2015  18:24  

2/3/2015  23:38  

2/4/2015  4:53  

2/4/2015  13:08  

2/4/2015  18:22  

2/4/2015  23:36  

2/5/2015  4:51  

2/5/2015  10:05  

2/5/2015  15:19  

2/5/2015  20:33  

2/6/2015  1:48  

2/6/2015  7:02  

2/6/2015  12:16  

2/6/2015  17:31  

2/6/2015  22:45  

2/7/2015  3:59  

2/7/2015  9:14  

2/7/2015  14:28  

2/7/2015  19:42  

2/8/2015  0:56  

2/8/2015  6:11  

2/8/2015  11:25  

2/8/2015  16:39  

2/8/2015  21:54  

2/9/2015  3:08  

2/9/2015  8:22  

2/9/2015  13:37  

2/9/2015  18:51  

2/10/2015  0:05  

2/10/2015  5:19  

2/10/2015  10:34  

2/10/2015  15:48  

2/10/2015  21:02  

2/11/2015  2:17  

Outdo

or  air  pa

r+cle  consen

tra+

on  PM10    μ

g/m

3  

I/O  ra

+o  

Date  &  Time  

I/O  ra6o  

PM  10  

premises  overpressurised      (-­‐6  Pa)  -­‐>  (4  Pa)  

premises  pressure  returned  to  normal              (4  Pa)  -­‐>  (-­‐6  Pa)  

Air0  room  air  cleaner  switched  on  

Air0  room  air  cleaner  switched  off  

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Supply air filter efficiencies

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Loaded filter (12.5.2015)

Electret filter has now been used for 14 weeks. Pressure drop has increased from 30 Pa to 53 Pa and charger voltage has increased from 6.8 kV to 7.7 kV. Slow pressure drop increase indicates that changing interval of the filter is more than 6 months. Increase in charger voltage indicates that corona wires are slighly contaminated

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Residency monitoring system installed in the residence hallway

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Main findings at residence building measurements (1)

§ HVAC system at recidence building provides an excellent platform for piloting new filtration solutions

§ The measurement system worked OK and the results proofed that indoor air particle concentration can be reduced significantly

§ The screen at hallway enables presenting the data on-line § Installing more efficient supply air filters (Lifa Air) resulted

extremely low particle concentrations in supply air § Particle Indoor/Outdoor concentration ratio is not as good as the

HVAC system would enable

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Main findings at residence building measurements (2)

§ Overpressurizing the building proofed that leakages through the building envelope is the main indoor impurity source

§ Recirculating room air cleaner reduced the concentration further, dimensioning the clean air delivery rate must be emhasized

§ The HVAC system uses a lot of recirculation, it can be seen in high CO2 values during dense occupation.

§ In the future PM2.5, CO2 and energy consumption should be optimized simultaneously in HVAC control system

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