| 1. |
- Bachmaier, Hans, et al.
(författare)
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Bereal - method for pellet stoves : Field test and round robin
- 2017
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Ingår i: European Biomass Conf. Exhib. Proc.. - : ETA-Florence Renewable Energies. ; , s. 642-647
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Konferensbidrag (refereegranskat)abstract
- Recent pellet stoves perform excellently under type test conditions. In contrast, typical real life emissions show significantly higher values under usual operational conditions. Consequently, type testing procedures may not account for real life stove operation and, thus, do not allow to distinguish between low- and high-tech appliances. The EU-project beReal aimed at the development of a testing method for pellet stoves that reflects real life operations better and to support innovative pellet stoves that perform well under typical operational conditions. Based on an online survey and field observations, an advanced real life testing procedure for pellet stoves was established reflecting real life user behavior, e.g. regarding different load levels and the ignition phase. A field test was designed at the end of the project to demonstrate the applicability and practical relevance. The field test proved that emission values for beReal at the test stand and in the field stay within the same range. A Round Robin test proved the repeatability and reproducibility of the beReal testing procedure. The beReal method can be reproduced with the same statistical variability or performed even better than the type testing method with exception of PM between different laboratories. © 2017, ETA-Florence Renewable Energies. All rights reserved.
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| 2. |
- Carvalho, Lara, et al.
(författare)
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Performance of a pellet boiler fired with agricultural fuels
- 2013
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 104, s. 286-296
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Tidskriftsartikel (refereegranskat)abstract
- The increasing demand for woody biomass increases the price of this limited resource, motivating the growing interest in using woody materials of lower quality as well as non-woody biomass fuels for heat production in Europe. The challenges in using non-woody biomass as fuels are related to the variability of the chemical composition and in certain fuel properties that may induce problems during combustion. The objective of this work has been to evaluate the technical and environmental performance of a 15 kW pellet boiler when operated with different pelletized biomass fuels, namely straw (Triticum aestivum), Miscanthus (Miscanthus × giganteus), maize (Zea mays), wheat bran, vineyard pruning (from Vitis vinifera), hay, Sorghum (Sorghum bicolor) and wood (from Picea abies) with 5% rye flour. The gaseous and dust emissions as well as the boiler efficiency were investigated and compared with the legal requirements defined in the FprEN 303-5 (final draft of the European standard 303-5). It was found that the boiler control should be improved to better adapt the combustion conditions to the different properties of the agricultural fuels. Additionally, there is a need for a frequent cleaning of the heat exchangers in boilers operated with agricultural fuels to avoid efficiency drops after short term operation. All the agricultural fuels satisfied the legal requirements defined in the FprEN 303-5, with the exception of dust emissions during combustion of straw and Sorghum. Miscanthus and vineyard pruning were the best fuels tested showing comparable emission values to wood combustion.
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| 3. |
- Klauser, Franziska, et al.
(författare)
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Effect of Oxidizing Honeycomb Catalysts Integrated in a Firewood Room Heater on Gaseous and Particulate Emissions, Including Polycyclic Aromatic Hydrocarbons (PAHs)
- 2018
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:11, s. 11876-11886
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Tidskriftsartikel (refereegranskat)abstract
- Residential wood combustion is linked to a significant extent of emissions of polycyclic aromatic hydrocarbons (PAHs), which represent highly toxic, semivolatile pollutants. The use of catalysts reveals an effective measure to reduce emissions, especially gaseous flue gas compounds (carbon monoxide (CO) and organic gaseous compounds (OGC)). Their effect on toxicologically relevant PAHs is not clarified yet. In this work, the impact of two commercially available oxidizing platinum/palladium catalysts with either metallic or ceramic honeycomb carriers was examined under real-life operating conditions of a firewood room heater. The catalytic effect on CO and OGC, total suspended particles (TSP), total carbon (TC), elemental carbon (EC), organic carbon (OC), and 19 different PAHs, including 16 EPA PAHs (PAHs defined by the Environmental Protection Agency as priority pollutants) was evaluated by parallel measurements of catalytically treated and untreated flue gas from firewood combustion. The metallic catalyst, having a reaction surface that is 3.5 times greater than the ceramic catalyst, leads to a more-pronounced impact. Both types, the ceramic and the metallic catalyst, led to distinct reductions of CO (-69%, -88%) and OGC (-27%, -39%). In the test with the metallic catalyst, TSP increased (+17%) and PAHs were clearly reduced (-63%). This reduction was exclusively related to the higher-molecular-weight PAHs, such as the particularly toxic benzo(a)pyrene. Carbonaceous fractions (TC, EC, and OC) were not affected significantly. The toxicity of emissions arising from EPA PAHs can be clearly reduced by catalytic treatment. Moreover, the increase of TSP opens new questions, which must be clarified before the investigated catalysts are recommended as suitable secondary measure for emission abatement.
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| 4. |
- Klauser, Franziska, et al.
(författare)
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Emission characterization of modern wood stoves under real-life oriented operating conditions
- 2018
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 192, s. 257-266
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Tidskriftsartikel (refereegranskat)abstract
- The quality of emission inventories substantially bases on the reliability of used emission factors (EFs). In this work EFs were studied according to recently published characterization methods, called “beReal”, reflecting real life operating conditions in Europe. EFs for four pellet stoves and nine firewood appliances (roomheaters and cookers) of carbon monoxide (CO), organic gaseous compounds (OGC), nitrogen oxides, total solid particles (TSP) of hot and of diluted flue gas, total, elemental and organic carbon (TC, EC, OC) and benzo(a)pyrene were determined.CO, OGC, TSPs, TC, EC and OC emissions from firewood appliances were significantly higher than for pellet stoves, indicating the high relevance of classifying appliances according to the operation type. TSP sampled from diluted flue gas at 40 °C (28 mg MJ−1 to 271 mg MJ−1 based on fuel input) was higher than TSP sampled from hot flue gas (2170 mg MJ−1 to 70 mg MJ−1). This reveals the high relevance of sampling conditions for the determination of real life emissions. Benzo(a)pyrene emissions scattered over a wide range (0.5 μg MJ−1 to 129.8 μg MJ−1) indicating high sensitivity to unfavorable combustion conditions. Therefore a higher number of experimentally determined emissions factors could improve the reliability of EFs for inventories. CO emissions measured in beReal tests were substantially higher than official type tests, thus showing that type testing results provide limited information for the determination of real life emissions.A systematic evaluation of EFs with defined real life methods like beReal would substantially improve the reliability of emission inventories.
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| 5. |
- Lichtenegger, Klaus, et al.
(författare)
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The role of leak air in a double-wall chimney
- 2015
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Ingår i: Heat and Mass Transfer. - : Springer Science and Business Media LLC. - 0947-7411 .- 1432-1181. ; 51:6, s. 787-794
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Tidskriftsartikel (refereegranskat)abstract
- In modern buildings with tight shells, often room-independent air supply is required for proper operation of biomass stoves. One possibility to arrange this supply is to use a double-wall chimney with flue gas leaving through the pipe and fresh air entering through the annular gap. A one-dimensional quasi-static model based on balance equations has been developed and compared with experimental data. Inclusion of leak air is crucial for reproduction of the experimental results.
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| 6. |
- Lichtenegger, Klaus, et al.
(författare)
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Towards a Stochastic Cellular Automata Model of Log Wood Combustion
- 2014
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 490:1
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Tidskriftsartikel (refereegranskat)abstract
- Describing the combustion of log wood and others solid fuels with complex geometry, considerable water content and often heterogenous struture is a nontrivial task. Stochastic Cellular Automata models offer a promising approach for modelling such processes. Combustion models of this type exhibit several similarities to the well-known forest fire models, but there are also significant differences between those two types of models. These differences call for a detailed analysis and the development of supplementary modeling approaches. In this article we define a qualitative two-dimensional model of burning log wood, discuss the most important differences to classical forest fire models and present some preliminary results. © Published under licence by IOP Publishing Ltd.
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| 7. |
- Sedlmayer, Irene, et al.
(författare)
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Determination of off-gassing and self-heating potential of wood pellets – Method comparison and correlation analysis
- 2018
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 234, s. 894-903
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Tidskriftsartikel (refereegranskat)abstract
- Several methods for identifying the phenomena of self-heating and off-gassing during production, transportation and storage of wood pellets have been developed in recent years. Research focused on the exploration of the underlying mechanisms, influencing factors or the quantification of self-heating or off-gassing tendencies. The present study aims at identifying a clear correlation between self-heating and off-gassing. Thus, different methods for determining self-heating and off-gassing potentials of wood pellets are compared. Therefore, eleven wood pellet batches from the European market were analyzed. For this investigation, three methods for the determination of self-heating, like isothermal calorimetry, oxi-press and thermogravimetric analysis, and four methods for off-gassing, like volatile organic compound (VOC) emissions measurements, gas phase analysis of stored pellets in a closed container by offline and by glass flask method and determination of fatty and resin acids content, were performed. Results were ranked according to the self-heating and off-gassing tendency providing a common overview of the analyzed pellets batches. Relations between different methods were investigated by Spearman's correlation coefficient. Evaluation of the results revealed an equal suitability of offline and glass flask methods to predict off-gassing tendency and indicated a very significant correlation with isothermal calorimetry for the identification of self-heating tendency. The thermogravimetric analysis as well as the fatty and resin acids determination proved to be insufficient for the exclusive assessment of self-heating and off-gassing tendency, respectively.
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| 8. |
- Sedlmayer, Irene, et al.
(författare)
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Off-gassing reduction of stored wood pellets by adding acetylsalicylic acid
- 2020
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Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 198
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Tidskriftsartikel (refereegranskat)abstract
- During transportation and storage of wood pellets various gases are formed leading to toxic atmosphere. Various influencing factors and measures reducing off-gassing have already been investigated. The present study aims at applying an antioxidant, acetylsalicylic acid (ASA), to reduce off-gassing from wood pellets by lowering wood extractives oxidation. Therefore, acetylsalicylic acid was applied in industrial and laboratory pelletizing processes. Pine and spruce sawdust (ratio 1:1) were pelletized with adding 0-0.8% (m/m) ASA. Glass flasks measurements confirmed off-gassing reduction by adding ASA for all wood pellets investigated.The biggest effect was achieved by adding 0.8% (m/m) ASA in the industrial pelletizing experiments where the emission of volatile organic compounds (VOCtot) was reduced by 82% and a reduction of carbon monoxide (CO) and carbon dioxide (CO2) emissions by 70% and 51%, respectively, could be achieved. Even an addition of 0.05% (m/m) ASA led to off-gassing reduction by >10%. A six week storage experiment to investigate the long-term effectivity of ASA addition revealed, that antioxidant addition was effective in reducing CO-, CO2- and VOCtot-release, especially during the first four weeks of the storage experiment, after which time the relative reduction effect was significantly decreased.
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