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Influence of wood species and burning conditions on particle emission characteristics in a residential wood stove
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Thermochemical Energy Conversion Laboratory)ORCID iD: 0000-0003-2497-5294
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Thermochemical Energy Conversion Laboratory)
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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: urn:nbn:se:umu:diva-127360OAI: oai:DiVA.org:umu-127360DiVA: diva2:1045492
Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2016-11-21
In thesis
1. Particle emissions from residential wood and biodiesel combustion
Open this publication in new window or tab >>Particle emissions from residential wood and biodiesel combustion
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
Combustion, biomass, wood, biodiesel, particulate matter, emissions, aerosols, physicochemical properties, size distribution, PAH
National Category
Other Natural Sciences
Identifiers
urn:nbn:se:umu:diva-127460 (URN)978-91-7601-605-3 (ISBN)
Public defence
2016-12-14, N460, Naturvetarhuset, Johan Bures Väg 16, Umeå, 13:00 (Swedish)
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Available from: 2016-11-23 Created: 2016-11-14 Last updated: 2016-11-22Bibliographically approved

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