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Particle emissions from residential wood and biodiesel combustion
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Thermochemical Energy Conversion Laboratory)ORCID iD: 0000-0003-2497-5294
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Emissions from anthropogenic combustion sources, such as vehicles and biomass combustion, contribute significantly to ambient particulate matter (PM) both on a local and global scale. Exposure to ambient PM and air pollution in general is linked to a variety of different health effects and it has been estimated that as many as 2.1 million premature deaths each year, due to cardiopulmonary disease and lung cancer, are caused by the changes in anthropogenic air pollution since pre-industrial times. There is today still a lack of information regarding the emissions of different specific particulate emission components, e.g. soot, polycyclic aromatic hydrocarbons (PAHs), oxy-PAHs combined with details about the behaviour of different fuels under varying combustion conditions. The overall objective of this work was to provide new knowledge regarding physical and chemical properties of PM from solid and liquid biofuels, which are important for the viewpoint of human health and atmospheric pollution. This was achieved by experimental studies of the combustion of biomass using a residential wood stove and by introducing biodiesel to an off-road engine, thereby investigating two major emission sources for PM and gaseous emissions.

From the two papers regarding biodiesel included in this thesis, it can be concluded that the introduction of the biodiesel, and potentially other renewable fuels, can in a considerable way change the exhaust particle emissions. This could have implications for the assessment of exhaust from engines running on biodiesel fuels, especially when introducing biodiesel in existing and older engines.

The results from the wood combustion research performed showed some important considerations regarding both specific particle properties and the influences of different burning conditions and fuels. One major finding, based on several of the included studies, was that a proper operation of a wood stove is of major importance to avoid unfavourable burning condition and elevated emissions of soot and organic particles, regardless of the wood species used. Some specific occasions during the burning phases in batch wise wood combustion were also identified as important for the overall emissions. The results from this research has given new specific insights into the emissions from wood stoves and should be of relevance for both technological development of residential appliances, emission testing/certification, information to users and legislation.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2016. , 75 p.
Keyword [en]
Combustion, biomass, wood, biodiesel, particulate matter, emissions, aerosols, physicochemical properties, size distribution, PAH
National Category
Other Natural Sciences
Identifiers
URN: urn:nbn:se:umu:diva-127460ISBN: 978-91-7601-605-3OAI: oai:DiVA.org:umu-127460DiVA: diva2:1046395
Public defence
2016-12-14, N460, Naturvetarhuset, Johan Bures Väg 16, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2016-11-23 Created: 2016-11-14 Last updated: 2016-11-22Bibliographically approved
List of papers
1. Physical and chemical properties of RME biodiesel exhaust particles without engine modifications
Open this publication in new window or tab >>Physical and chemical properties of RME biodiesel exhaust particles without engine modifications
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2016 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 186, 261-269 p.Article in journal (Refereed) Published
Abstract [en]

A major contributor to ambient particulate air pollution is exhaust from diesel engines and other vehicles, which can be linked to different adverse health effects. During the last decades, a global drive towards finding sustainable and clean bio-based alternative fuels for the transport sector has taken place and biodiesel is one of the most established alternatives today. To better assess the overall effects on a public health level when introducing biodiesel and other renewable fuels, a better understanding of the detailed exhaust particle properties, is needed. In this work, the physical and chemical properties of biodiesel exhaust particles were studied in comparison to standard diesel exhaust emissions, in an existing engine without modifications, focusing on particulate carbonaceous matter and PAH/Oxy-PAH as well as fine particle size distribution. An older off-road engine, produced between 1996 and 2004, was used with three different fuels/fuel blends; (1) 100 wt% low-sulfur standard petro diesel (SD), (2) 100 wt% rapeseed methyl ester biodiesel (B100) and (3) a blended fuel – B30 consisting of 30 wt% RME and 70 wt% SD. The study focused mainly on emissions from transient engine operation, but includes also idling conditions. The gaseous emissions measured for the biodiesel fuel were in general in accordance with previous reported data in the literature, and compared to the standard petro diesel the emissions of CO was lower while NOx emissions increased. The particulate mass concentration during transient operation was almost halved compared to when petro diesel was used and this was associated with a decrease in average particle size. The shift in particle mass and size was associated with a higher fraction of organic matter in general, considerable less PAH’s but a relative higher fraction of Oxy-PAH’s, when shifting from petro diesel to biodiesel.

Keyword
Biodiesel, RME, Diesel engine, Exhaust emissions, Particles characteristics, PAH
National Category
Energy Engineering
Identifiers
urn:nbn:se:umu:diva-127037 (URN)10.1016/j.fuel.2016.08.062 (DOI)000385318600027 ()
Funder
Bio4EnergyAFA InsuranceSwedish Heart Lung Foundation
Available from: 2016-10-26 Created: 2016-10-26 Last updated: 2016-11-21Bibliographically approved
2. Effects of dilution conditions on particle formation and size distribution in engine exhaust emissions when introducing biodiesel in comparison to standard petro diesel
Open this publication in new window or tab >>Effects of dilution conditions on particle formation and size distribution in engine exhaust emissions when introducing biodiesel in comparison to standard petro diesel
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Air pollution, in particular ambient particulate matter (PM), can be linked to a variety of different health effects, and a major contributor to the PM pollution is exhaust from diesel engines and other vehicles. In the global drive towards finding sustainable and clean bio-based alternative fuels for the transport sector, biodiesel is one of the most established alternative. However, there is considerable variation in emission data for biodiesel, preferably explained by influences of engine technology and operating conditions as well as dilution sampling strategy. In this study the focus was therefore to study the effects of dilution conditions on the particle formation and size distribution in the exhaust emissions from an off road engine, when introducing RME biodiesel in comparison to standard petro diesel. Particle size distribution and number concentration were measured on-line with the use of a fast mobility spectrometer, during a transient operation and without engine modification. Differences in particle characteristics were elucidated in the raw exhaust versus diluted exhaust at two subsequent sampling points with different dilution ratios. In addition, the influences on the exhaust particle properties of changing the lubrication oil was investigated. It was found that biodiesel in general generated more nucleation mode particles then petro diesel, and after the oil exchange the total particle number concentration was increased even more. It was also seen that the custom-built dilution setup favors generation of nucleation mode particles, which is in line with real life conditions in chase and road side experiments. However, when using heated primary dilution and a heated line in the raw exhaust the formation of nucleation mode particles was suppressed. Overall, it was concluded that the introduction of the biodiesel, and potentially other renewable fuels, can in a considerable way change the exhaust particle emission and characteristics. This could have implications for the assessment of exhaust from engines running on biodiesel fuels, especially when introducing biodiesel in existing and older engines.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:umu:diva-127459 (URN)
Available from: 2016-11-14 Created: 2016-11-14 Last updated: 2016-11-21
3. Evaluation of a novel chamber setup for human exposures of biomass combustion aerosols
Open this publication in new window or tab >>Evaluation of a novel chamber setup for human exposures of biomass combustion aerosols
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Based on a vast number of epidemiological studies there is today a consensus that increased concentrations of ambient particulate matter air pollution cause adverse health effects such as mortality, hospitalizations, cardiovascular events, respiratory symptoms and reduced lung function. The use of controlled laboratory studies with human exposure chambers can give unique opportunities to directly examine specific exposure conditions and cause-effect relationship with relevant concentrations and particle types. In this paper, the design of a novel chamber setup for human exposures of biomass combustion aerosols is described with an evaluation of the systems function under different conditions (e.g. air exchange rates and target PM1 concentrations). Several different research biomass combustion systems are available in combination with extensive and advanced monitoring and characterization of the gaseous and particle emissions used for exposures. Examples, with data from three performed human exposure campaigns, are included and discussed as a basis for the evaluation of the whole setup, with the target to generate stable conditions in the chamber using different kinds of biomass combustion aerosols. Based on the evaluation of function and present exposure experiences it can be concluded that the chamber setup and biomass aerosol generation systems is able to produce a stable aerosol concentration in the chamber of different particle types.  Overall, the human exposure setup for biomass combustion aerosols together with the integrated biomass combustion laboratory gives extensive possibilities for designing different whole body human exposure studies for a variety of biomass combustion aerosols as well as other experimental aerosol research.

National Category
Respiratory Medicine and Allergy Energy Engineering
Identifiers
urn:nbn:se:umu:diva-127361 (URN)
Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2016-11-21
4. Influence of wood species and burning conditions on particle emission characteristics in a residential wood stove
Open this publication in new window or tab >>Influence of wood species and burning conditions on particle emission characteristics in a residential wood stove
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Emissions from small scale residential biomass combustion are a major source of indoor and outdoor particulate matter (PM) air pollution, and the performance of stoves, boilers and fireplaces have been shown to be influenced both by fuel properties, technology and user behaviour (firing procedures). Still, rather scarce information is available regarding the relative importance of these variables for the particle characteristics and emissions of different particulate components, e.g. soot, PAH, oxy-PAH, and metals. In particular, the behaviour of different wood fuels under varying firing procedures and combustion conditions, has not been studied thoroughly. The objective of this work was therefore to elucidate the influence of wood species and combustion conditions on particle emission characteristics in a typical Nordic residential wood stove. The emissions from four different wood species were investigated at two controlled combustion conditions including nominal and high burn rates, with focus on physical and chemical properties of the fine particulate matter. Considerably elevated carbonaceous particle emissions (soot and organics) was found during high burn rate conditions, associated with a shift in particle number size distribution towards a higher fraction of larger particles. In some cases, as here seen for pine, the specific fuel properties can affect the combustion performance and thereby also influence particle and PAH emissions. For the inorganic ash particles, the content in the fuel, and not burning condition, was found to be the main determining factor as seen by the increased emissions of alkali salts for aspen. For the first time, wood stove emission data on 11 specific oxy-PAHs together with 45 PAH was combined with controlled variations of burning conditions and fuels. The oxy-PAH/PAH ratio during high burn rate was found to increase, suggesting an enrichment of particulate oxy-PAH, information that can be of relevance when assessing the toxicological properties of the PM. Accordingly, the main influence on emission performance and particle characteristics was seen between different burn rates, and this study clearly illustrates the major importance of proper operation to avoid unfavorable burning condition regardless of the wood species used.

National Category
Environmental Sciences Bioenergy
Identifiers
urn:nbn:se:umu:diva-127360 (URN)
Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2016-11-21
5. Particulate hydroxy-PAH emissions from a residential wood log stove using different fuels and burning conditions
Open this publication in new window or tab >>Particulate hydroxy-PAH emissions from a residential wood log stove using different fuels and burning conditions
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2016 (English)In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 140, 1-9 p.Article in journal (Refereed) Published
Abstract [en]

Hydroxylated polycyclic aromatic hydrocarbons are oxidation products of polycyclic aromatic hydrocarbons, but have not been studied as extensively as polycyclic aromatic hydrocarbons. Several studies have however shown that hydroxylated polycyclic aromatic hydrocarbons have toxic and carcinogenic properties. They have been detected in air samples in semi urban areas and combustion is assumed to be the primary source of those compounds. To better understand the formation and occurrence of particulate hydroxylated polycyclic aromatic hydrocarbons from residential wood log stove combustion, 9 hydroxylated polycyclic aromatic hydrocarbons and 2 hydroxy biphenyls were quantified in particles generated from four different types of wood logs (birch, spruce, pine, aspen) and two different combustion conditions (nominal and high burn rate). A previously developed method utilizing liquid chromatography photo ionization tandem mass spectrometry and pressurized liquid extraction was used. Polycyclic aromatic hydrocarbons were analyzed along with hydroxylated polycyclic aromatic hydrocarbons. The hydroxylated polycyclic aromatic hydrocarbon emissions varied significantly across different wood types and burning conditions; the highest emissions for nominal burn rate were from spruce and for high burn rate from pine burning. Emissions from nominal burn rate corresponded on average to 15% of the emissions from high burn rate, with average emissions of 218 mu g/MJ(fuel) and 32.5 mu g/MJ(fuel) for high burn rate and nominal burn rate, respectively. Emissions of the measured hydroxylated polycyclic aromatic hydrocarbons corresponded on average to 28% of polycyclic aromatic hydrocarbons emissions. This study shows that wood combustion is a large emission source of hydroxylated polycyclic aromatic hydrocarbons and that not only combustion conditions, but also wood type influences the emissions of hydroxylated polycyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons. There are few studies that have determined hydroxylated polycyclic aromatic hydrocarbons in emissions from wood combustion, and it is therefore necessary to further investigate the formation, occurrence and distribution of these compounds as they are present in significant amounts in wood smoke particles.

Keyword
OH-PAHs, Hydroxy-PAHs, PAHs, Wood combustion, Wood burning, Wood log stove
National Category
Meteorology and Atmospheric Sciences Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-124830 (URN)10.1016/j.atmosenv.2016.05.041 (DOI)000380083200001 ()
Available from: 2016-10-03 Created: 2016-08-26 Last updated: 2016-11-14Bibliographically approved
6. Particulate PAH Emissions from Residential Biomass Combustion: Time-Resolved Analysis with Aerosol Mass Spectrometry
Open this publication in new window or tab >>Particulate PAH Emissions from Residential Biomass Combustion: Time-Resolved Analysis with Aerosol Mass Spectrometry
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2014 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 12, 7143-7150 p.Article in journal (Refereed) Published
Abstract [en]

Time-resolved emissions of particulate polycyclic aromatic hydrocarbons (PAHs) and total organic particulate matter (OA) from a wood log stove and an adjusted pellet stove were investigated with high-resolution time-of-flight aerosol mass spectrometry (ANIS). The highest OA emissions were found during the addition of log wood on glowing embers, that is, slow burning pyrolysis conditions. These emissions contained about 1% PAHs (of OA). The highest PAH emissions were found during fast burning under hot air starved combustion conditions, in both stoves. In the latter case, PAHs contributed up to 40% of OA, likely due to thermal degradation of other condensable species. The distribution of PAHs was also shifted toward larger molecules in these emissions. ANIS signals attributed to PAHs were found at molecular weights up to 600 Da. The vacuum aerodynamic size distribution was found to be bimodal with a smaller mode (D-va similar to 200 nm) dominating under hot air starved combustion and a larger sized mode dominating under slow burning pyrolysis (D-va similar to 600 nm). Simultaneous reduction of PAHs, OA and total particulate matter from residential biomass combustion may prove to be a challenge for environmental legislation efforts as these classes of emissions are elevated at different combustion conditions.

National Category
Other Natural Sciences
Identifiers
urn:nbn:se:umu:diva-91200 (URN)10.1021/es500486j (DOI)000337646000075 ()
Available from: 2014-07-23 Created: 2014-07-21 Last updated: 2016-11-14Bibliographically approved
7. Influence of ozone initiated processing on the toxicity of aerosol particles from small scale wood combustion
Open this publication in new window or tab >>Influence of ozone initiated processing on the toxicity of aerosol particles from small scale wood combustion
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2015 (English)In: Atmospheric Environment, ISSN 1352-2310, Vol. 102, 282-289 p.Article in journal (Refereed) Published
Abstract [en]

Black carbon containing emissions from biomass combustion are being transformed in the atmosphere upon processing induced by tropospheric ozone and UV. The knowledge today is very limited on how atmospheric processing affects the toxicological properties of the emissions. The aim of this study was to investigate the influence of ozone initiated (dark) atmospheric processing on the physicochemical and toxicological properties of particulate emissions from wood combustion. Emissions from a conventional wood stove operated at two combustion conditions (nominal and hot air starved) were diluted and transferred to a chamber. Particulate matter (PM) was collected before and after ozone addition to the chamber using an impactor. Detailed chemical and physical characterization was performed on chamber air and collected PM. The collected PM was investigated toxicologically in vitro with a mouse macrophage model, endpoints included: cell cycle analysis, viability, inflammation and genotoxicity. The results suggest that changes in the organic fraction, including polycyclic aromatic hydrocarbons (PAHs) are the main driver for differences in obtained toxicological effects. Fresh hot air starved emissions containing a higher organic and PAH mass-fraction affected cell viability stronger than fresh emissions from nominal combustion. The PAH mass fractions decreased upon aging due to chemical degradation. Dark aging increased genotoxicity, reduced viability and reduced release of inflammatory markers. These differences were statistically significant for single doses and typically less pronounced. We hypothesize that the alterations in toxicity upon simulated dark aging in the atmosphere may be caused by reaction products that form when PAHs and other organic compounds react with ozone and nitrate radicals.

Keyword
Biomass combustion, Polycyclic aromatic hydrocarbons, Aging, Cell studies
National Category
Environmental Sciences Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:umu:diva-102306 (URN)10.1016/j.atmosenv.2014.11.068 (DOI)000349590300031 ()
Available from: 2015-06-24 Created: 2015-04-23 Last updated: 2016-11-14Bibliographically approved

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