scholarly journals Time-resolved analysis of primary volatile emissions and secondary aerosol formation potential from a small-scale pellet boiler

2017 ◽  
Vol 158 ◽  
pp. 236-245 ◽  
Author(s):  
Hendryk Czech ◽  
Simone M. Pieber ◽  
Petri Tiitta ◽  
Olli Sippula ◽  
Miika Kortelainen ◽  
...  
Keyword(s):  
Small Scale ◽  
Aerosol Formation ◽  
Time Resolved ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Volatile Emissions

scholarly journals Influence of fuel ethanol content on primary emissions and secondary aerosol formation potential for a modern flex-fuel gasoline vehicle

2016 ◽  
Author(s):  
Hilkka Timonen ◽  
Panu Karjalainen ◽  
Erkka Saukko ◽  
Sanna Saarikoski ◽  
Päivi Aakko-Saksa ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Compounds ◽  
Fuel Ethanol ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Aerosol Mass ◽  
Ethanol Content ◽  
Flex Fuel ◽  
Primary Emissions

Abstract. The effect of fuel ethanol content (10 %, 85 %, 100 %) on primary emissions and on subsequent secondary aerosol formation was investigated for a EURO5 flex-fuel gasoline vehicle. Emissions were characterized during the New European Driving Cycle (NEDC) using a comprehensive setup of high time resolution instruments. Detailed chemical composition of exhaust particulate matter (PM) was studied using a soot particle aerosol mass spectrometer (SP-AMS) and secondary aerosol formation using a potential aerosol mass (PAM) chamber. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease of aromatic BTEX (benzene, toluene, ethylbenzene and xylenes) compounds was observed when the amount of ethanol in fuel increased. In regard to particles, largest primary particulate matter concentrations and potential to form secondary particles were measured for the E10 fuel (10 % ethanol). As the ethanol content of the fuel increased, a significant decrease in average primary particulate matter concentrations over the NEDC cycle was found, PM emissions being 0.45, 0.25 and 0.15 mg m−3 for E10, E85 and E100, respectively. Similarly, a clear decrease in secondary aerosol formation potential was observed with larger contribution of ethanol in fuel. Secondary to primary PM ratios were 13.4, and 1.5 for E10 and E85, respectively. For E100 a slight decrease in PM mass was observed after the PAM chamber, indicating that the PM produced by secondary aerosol formation was less than the PM lost via e.g. wall losses or degradation of POA in the chamber. For all fuel blends, the formed secondary aerosol consisted mostly of organic compounds. For E10 the contribution of organic compounds containing oxygen increased from 35 %, measured for primary organics, to 62 % after the PAM chamber. For E85 the contribution of organic compounds containing oxygen increased from 42 % (primary) to 57 % (after the PAM chamber), whereas for E100 the amount of oxidized organics remained the same (approximately 62 %) with the PAM chamber when compared to the primary emissions.

scholarly journals Comparison of primary and secondary particle formation from natural gas engine exhaust and of their volatility characteristics

2017 ◽  
Author(s):  
Jenni Alanen ◽  
Pauli Simonen ◽  
Sanna Saarikoski ◽  
Hilkka Timonen ◽  
Oskari Kangasniemi ◽  
...  
Keyword(s):  
Natural Gas ◽  
Organic Aerosol ◽  
Liquid Fuels ◽  
Aerosol Formation ◽  
Engine Exhaust ◽  
Gas Engine ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Natural Gas Engine ◽  
Catalyst Temperature

Abstract. Natural gas usage in traffic and energy production sector is a growing trend worldwide, thus an assessment of its effects on air quality, human health and climate is required. Engine exhaust is a source of primary particulate emissions and secondary aerosol precursors that both contribute to air quality and can cause adverse health effects. Technologies, such as cleaner engines or fuels, that produce less primary and secondary aerosol could potentially significantly decrease the atmospheric particle concentrations and their adverse effects. In this study, we used a potential aerosol mass (PAM) chamber to investigate the secondary aerosol formation potential of natural gas engine exhaust. The PAM chamber was used with a constant UV-light voltage that resulted in an equivalent atmospheric age of 11 days at a maximum. The studied passenger car engine, retrofitted to run with natural gas, was observed to have a low or moderate secondary particle formation potential, although the simulated atmospheric ages were relatively long. The secondary organic aerosol (SOA) formation potential was measured to be 8–18 mg kgfuel−1. However, the mass of total aged particles, i.e. particle mass measured downstream the PAM chamber, was 6–184 times as high as the mass of the emitted primary exhaust particles. The total aged particles consisted mainly of nitrate, organic matter, sulfate and ammonium, the fractions depending on exhaust after-treatment and used engine parameters. Also the volatility, composition and concentration of the total aged particles were found to depend on the engine operating mode, catalyst temperature and catalyst type. For example, a high catalyst temperature promoted the formation of sulfate particles, whereas a low catalyst temperature promoted nitrate formation. However, especially the concentration of nitrate needed a long time, more than half an hour, to stabilize, which complicated the conclusions but also indicates the sensitivity of nitrate measurements on experimental parameters such as emission source and system temperatures. Sulfate was measured to have the highest evaporation temperature and nitrate the lowest. The evaporation temperature of ammonium depended on the fractions of nitrate and sulfate in the particles. The average volatility of the total aged particles was measured to be lower than that of primary particles, indicating better stability of the aged natural gas engine emitted aerosol in the atmosphere. According to the results of this study, the shift from traditional liquid fuels to natural gas can have a decreasing effect on total particle pollution in the atmosphere; in addition to the very low primary particle emissions, also the secondary organic aerosol formation potential of natural gas exhaust is lower or on the same level as the SOA formation potential measured on liquid fuels in previous studies.

scholarly journals A new oxidation flow reactor for measuring secondary aerosol formation of rapidly changing emission sources

2017 ◽  
Vol 10 (4) ◽  
pp. 1519-1537 ◽  
Author(s):  
Pauli Simonen ◽  
Erkka Saukko ◽  
Panu Karjalainen ◽  
Hilkka Timonen ◽  
Matthew Bloss ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Anthropogenic Sources ◽  
Emission Sources ◽  
Transient Effects ◽  
Aerosol Formation ◽  
Flow Reactors ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Environmental Chambers ◽  
Driving Conditions

Abstract. Oxidation flow reactors (OFRs) or environmental chambers can be used to estimate secondary aerosol formation potential of different emission sources. Emissions from anthropogenic sources, such as vehicles, often vary on short timescales. For example, to identify the vehicle driving conditions that lead to high potential secondary aerosol emissions, rapid oxidation of exhaust is needed. However, the residence times in environmental chambers and in most oxidation flow reactors are too long to study these transient effects ( ∼  100 s in flow reactors and several hours in environmental chambers). Here, we present a new oxidation flow reactor, TSAR (TUT Secondary Aerosol Reactor), which has a short residence time ( ∼  40 s) and near-laminar flow conditions. These improvements are achieved by reducing the reactor radius and volume. This allows studying, for example, the effect of vehicle driving conditions on the secondary aerosol formation potential of the exhaust. We show that the flow pattern in TSAR is nearly laminar and particle losses are negligible. The secondary organic aerosol (SOA) produced in TSAR has a similar mass spectrum to the SOA produced in the state-of-the-art reactor, PAM (potential aerosol mass). Both reactors produce the same amount of mass, but TSAR has a higher time resolution. We also show that TSAR is capable of measuring the secondary aerosol formation potential of a vehicle during a transient driving cycle and that the fast response of TSAR reveals how different driving conditions affect the amount of formed secondary aerosol. Thus, TSAR can be used to study rapidly changing emission sources, especially the vehicular emissions during transient driving.

scholarly journals A New Oxidation Flow Reactor for Measuring Secondary Aerosol Formation of Rapidly Changing Emission Sources

2016 ◽  
Author(s):  
Pauli Simonen ◽  
Erkka Saukko ◽  
Panu Karjalainen ◽  
Hilkka Timonen ◽  
Matthew Bloss ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Anthropogenic Sources ◽  
Emission Sources ◽  
Transient Effects ◽  
Aerosol Formation ◽  
Flow Reactors ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Environmental Chambers ◽  
Driving Conditions

Abstract. Oxidation flow reactors or environmental chambers can be used to estimate secondary aerosol formation potential of different emission sources. Emissions from anthropogenic sources, such as vehicles, often vary on short timescales. For example, to identify the vehicle driving conditions that lead to high potential secondary aerosol emissions, rapid oxidation of exhaust is needed. However, the residence times in environmental chambers and in most oxidation flow reactors are too long to study these transient effects. Here, we present a new oxidation flow reactor, TSAR (TUT Secondary Aerosol Reactor), which has a short residence time and near-laminar flow conditions. This allows studying e.g. the effect of vehicle driving conditions on secondary aerosol formation potential of the exhaust. We show that the flow pattern in TSAR is nearly laminar and particle losses are negligible. The secondary organic aerosol (SOA) produced in TSAR has a similar mass spectrum as the SOA produced in the state-of-the-art reactor, PAM (Potential Aerosol Mass). Both reactors produce the same amount of mass, but the TSAR has a higher time-resolution. We also show that the TSAR is capable of measuring secondary aerosol formation potential of a vehicle during a transient driving cycle, and that the fast response of the TSAR reveals how different driving conditions affect the amount of formed secondary aerosol. Thus, the TSAR can be used to study rapidly changing emission sources, especially the vehicular emissions during transient driving.

scholarly journals Influence of fuel ethanol content on primary emissions and secondary aerosol formation potential for a modern flex-fuel gasoline vehicle

2017 ◽  
Vol 17 (8) ◽  
pp. 5311-5329 ◽  
Author(s):  
Hilkka Timonen ◽  
Panu Karjalainen ◽  
Erkka Saukko ◽  
Sanna Saarikoski ◽  
Päivi Aakko-Saksa ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Compounds ◽  
Fuel Ethanol ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Aerosol Mass ◽  
Ethanol Content ◽  
Flex Fuel ◽  
Primary Emissions

Abstract. The effect of fuel ethanol content (10, 85 and 100 %) on primary emissions and on subsequent secondary aerosol formation was investigated for a Euro 5 flex-fuel gasoline vehicle. Emissions were characterized during a New European Driving Cycle (NEDC) using a comprehensive set-up of high time-resolution instruments. A detailed chemical composition of the exhaust particulate matter (PM) was studied using a soot particle aerosol mass spectrometer (SP-AMS), and secondary aerosol formation was studied using a potential aerosol mass (PAM) chamber. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease in aromatic BTEX (benzene, toluene, ethylbenzene and xylenes) compounds was observed when the amount of ethanol in the fuel increased. In regard to particles, the largest primary particulate matter concentrations and potential for secondary particle formation was measured for the E10 fuel (10 % ethanol). As the ethanol content of the fuel increased, a significant decrease in the average primary particulate matter concentrations over the NEDC was found. The PM emissions were 0.45, 0.25 and 0.15 mg m−3 for E10, E85 and E100, respectively. Similarly, a clear decrease in secondary aerosol formation potential was observed with a larger contribution of ethanol in the fuel. The secondary-to-primary PM ratios were 13.4 and 1.5 for E10 and E85, respectively. For E100, a slight decrease in PM mass was observed after the PAM chamber, indicating that the PM produced by secondary aerosol formation was less than the PM lost through wall losses or the degradation of the primary organic aerosol (POA) in the chamber. For all fuel blends, the formed secondary aerosol consisted mostly of organic compounds. For E10, the contribution of organic compounds containing oxygen increased from 35 %, measured for primary organics, to 62 % after the PAM chamber. For E85, the contribution of organic compounds containing oxygen increased from 42 % (primary) to 57 % (after the PAM chamber), whereas for E100 the amount of oxidized organics remained the same (approximately 62 %) with the PAM chamber when compared to the primary emissions.

scholarly journals Impacts of primary emissions and secondary aerosol formation on air pollution in an urban area of China during the COVID-19 lockdown

2021 ◽  
Vol 150 ◽  
pp. 106426
Author(s):  
Jie Tian ◽  
Qiyuan Wang ◽  
Yong Zhang ◽  
Mengyuan Yan ◽  
Huikun Liu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Urban Area ◽  
Aerosol Formation ◽  
Secondary Aerosol ◽  
Primary Emissions

scholarly journals Comparison of primary and secondary particle formation from natural gas engine exhaust and of their volatility characteristics

2017 ◽  
Vol 17 (14) ◽  
pp. 8739-8755 ◽  
Author(s):  
Jenni Alanen ◽  
Pauli Simonen ◽  
Sanna Saarikoski ◽  
Hilkka Timonen ◽  
Oskari Kangasniemi ◽  
...  
Keyword(s):  
Air Quality ◽  
Natural Gas ◽  
Particulate Emissions ◽  
Engine Exhaust ◽  
Gas Engine ◽  
Secondary Aerosol ◽  
Formation Potential ◽  
Natural Gas Engine ◽  
Evaporation Temperature ◽  
Catalyst Temperature

Abstract. Natural gas usage in the traffic and energy production sectors is a growing trend worldwide; thus, an assessment of its effects on air quality, human health and climate is required. Engine exhaust is a source of primary particulate emissions and secondary aerosol precursors, which both contribute to air quality and can cause adverse health effects. Technologies, such as cleaner engines or fuels, that produce less primary and secondary aerosols could potentially significantly decrease atmospheric particle concentrations and their adverse effects. In this study, we used a potential aerosol mass (PAM) chamber to investigate the secondary aerosol formation potential of natural gas engine exhaust. The PAM chamber was used with a constant UV-light voltage, which resulted in relatively long equivalent atmospheric ages of 11 days at most. The studied retro-fitted natural gas engine exhaust was observed to form secondary aerosol. The mass of the total aged particles, i.e., particle mass measured downstream of the PAM chamber, was 6–268 times as high as the mass of the emitted primary exhaust particles. The secondary organic aerosol (SOA) formation potential was measured to be 9–20 mg kgfuel−1. The total aged particles mainly consisted of organic matter, nitrate, sulfate and ammonium, with the fractions depending on exhaust after-treatment and the engine parameters used. Also, the volatility, composition and concentration of the total aged particles were found to depend on the engine operating mode, catalyst temperature and catalyst type. For example, a high catalyst temperature promoted the formation of sulfate particles, whereas a low catalyst temperature promoted nitrate formation. However, in particular, the concentration of nitrate needed a long time to stabilize – more than half an hour – which complicated the conclusions but also indicates the sensitivity of nitrate measurements on experimental parameters such as emission source and system temperatures. Sulfate was measured to have the highest evaporation temperature, and nitrate had the lowest. The evaporation temperature of ammonium depended on the fractions of nitrate and sulfate in the particles. The average volatility of the total aged particles was measured to be lower than that of primary particles, indicating better stability of the aged natural gas engine-emitted aerosol in the atmosphere. According to the results of this study, the exhaust of a natural gas engine equipped with a catalyst forms secondary aerosol when the atmospheric ages in a PAM chamber are several days long. The secondary aerosol matter has different physical characteristics from those of primary particulate emissions.

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