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Peer Reviewed Scientific Journals | 2017

Online experiments and modelling with a detailed reaction scheme of single particle biomass pyrolysis.

Anca-Couce A, Sommersacher P, Scharler R. Online experiments and modelling with a detailed reaction scheme of single particle biomass pyrolysis. Journal of Analytical and Applied Pyrolysis. Available online 17 July 2017

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Detailed reaction schemes and experimental data for the online release of pyrolysis volatiles are required to gain a more fundamental understanding of biomass pyrolysis, which would in turn allow the process to be controlled in a more precise way and the development of more targeted applications. A detailed online characterisation of pyrolysis products has been conducted in single particle experiments with spruce pellets at different temperatures, obtaining a good closure of the elemental mass balances. The yields and online release of CO, CO2, H2O, CH4, other light hydrocarbons and total organic condensable species, as well as char yield and composition, can be predicted with a reasonable accuracy with the application of a single particle model, coupled with a detailed pyrolysis scheme, and a simple one-step scheme for tar cracking. In order to achieve it, improvements have been conducted in the pyrolysis scheme, mainly concerning the release of light hydrocarbons and char yield and composition. Deviations are still present in the different groups in which organic condensable species can be classified.


Conference contributions | 2014

"BioCAT – Clean air technology for small-scale combustion systems"

Reichert G, Wöhler M, Schwabl M, Schmidl C, Aigenbauer S, Bachmaier H, Figl F, Hartmann H, Haslinger W, Kirchhof J, Stressler H, Sturmlechner R, Turowski P, Voglauer B. BioCAT – Clean air technology for small-scale combustion systems, 4. Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria. (oral presentation)

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Conference contributions | 2015

"Investigations on the catalytic activity of bed material coating regarding the water-gas-shift reaction and the steam reforming of model compounds for lighter and heavier hydrocarbons"

Kuba M, Havlik F, Kirnbauer F, Hofbauer H. Investigations on the catalytic activity of bed material coating regarding the water-gas-shift reaction and the steam reforming of model compounds for lighter and heavier hydrocarbons, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

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Technical Reports | 2017

2016 Survey of Non-Starch Alcohol and Renewable Hydocarbon Biofuels Producers

Warner E, Bacovsky D, Schwab A. 2016 Survey of Non-Starch Alcohol and Renewable Hydocarbon Biofuels Producers. 2016 Survey of Non-Starch Alcohol and Renewable Hydocarbon Biofuels Producers. February 2017.

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Peer Reviewed Scientific Journals | 2016

2250-h long term operation of a water gas shift pilot plant processing tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant

Kraussler M, Binder M, Hofbauer H. 2250-h long term operation of a water gas shift pilot plant processing tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant. International Journal of Hydrogen Energy. 27 April 2016;41(15): 6247-6258.

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Conference contributions | 2012

2nd Generation Biofuels from Biomass by steam gasification

Rauch R. 2nd Generation Biofuels from Biomass by steam gasification, 1. Nürnberger Fach-Kolloquium Methanisierung und Second Generation Fuels 2012, 29th-30th of May 2012, Nürnberg, Germany.

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Peer Reviewed Scientific Journals | 2011

A carbon-cycle-based stochastic cellular automata climate model

Lichtenegger K, Schappacher W. A carbon-cycle-based stochastic cellular automata climate model. International Journal of Modern Physics C. 2011;22(6):607-621.

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In this paper a stochastic cellular automata model is examined, which has been developed to study a "small" world, where local changes may noticeably alter global characteristics. This is applied to a climate model, where global temperature is determined by an interplay between atmospheric carbon dioxide and carbon stored by plant life. The latter can be released by forest fires, giving rise to significant changes of global conditions within short time.


Contributions to trade journals | 2009

A cell agglomeration algorithm for accelerating detailed chemistry. In: Combustion Theory and Modelling

Goldin GM, Ren Z, Zahirovic S. A cell agglomeration algorithm for accelerating detailed chemistry in CFD. Combustion Theory and Modelling. 2009;13(4):721-39.

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A cell agglomeration algorithm is proposed to mitigate the computational cost of incorporating detailed chemical kinetics in multi-dimensional Computational Fluid Dynamics (CFD) simulations. Cells that are close in species and energy composition space are agglomerated before calling the reaction integrator, substantially reducing the number of chemistry integrations. The algorithm is generalized and applicable to any reacting flow configuration, and the accuracy is fully controllable. A dynamic hash table is used to efficiently bin cells into high dimensional hyper-cubes in composition space. The method is applied to four different CFD simulations and the speed-up and incurred error are assessed for a range of agglomeration tolerances and table dimensions. The proposed approach exhibits up to an order of magnitude speed-up with a relatively moderate decrease in accuracy.


Reviewed Conference Papers | 2012

A CFD model for thermal conversion of thermally thick biomass particles

Mehrabian R, Zahirovic S, Scharler R, Obernberger I, Kleditzsch S, Wirtz S, et al. A CFD model for thermal conversion of thermally thick biomass particles. Fuel Process Technol. 2012;95:96-108.

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A one-dimensional model for the thermal conversion of thermally thick biomass particles is developed for the simulation of the fuel bed of biomass grate furnaces. The model can be applied for cylindrical and spherical particles. The particle is divided into four layers corresponding to the main stages of biomass thermal conversion. The energy and mass conservation equations are solved for each layer. The reactions are assigned to the boundaries. The model can predict the intra-particle temperature gradient, the particle mass loss rate as well as the time-dependent variations of particle size and density, as the most essential features of particle thermal conversion. When simulating the fuel bed of a biomass grate furnace, the particle model has to be numerically efficient. By reducing the number of variables and considering the lowest possible number of grid points inside the particle, a reasonable calculation time of less than 1 min for each particle is achieved. Comparisons between the results predicted by the model and by the measurements have been performed for different particle sizes, shapes and moisture contents during the pyrolysis and combustion in a single-particle reactor. The results of the model are in good agreement with experimental data which implies that the simplifications do not impair the model accuracy.


Other Publications | 2018

A flexible low cost PV/EV microgrid controller concept based on a Raspberry Pi

Stadler M. A flexible low cost PV/EV microgrid controller concept based on a Raspberry Pi. Working Paper, Center for Energy and innovative Technologies (CET) and Bioenergy 2020+ GmbH, June 2018.

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Peer Reviewed Scientific Journals | 2018

A higher-order generalization of the NPK-method.

Birkelbach F, Deutsch M, Flegkas S, Winter F, Werner A. A higher-order generalization of the NPK-method. Thermochimica Acta, 9 January 2018;661:27-33.

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A novel algorithm to identify the full kinetic model of solid state reactions according to the General Kinetic Equation is presented. It is a higher-order generalization of the Non-Parametric Kinetics method (NPK-method) and allows for the simultaneous identification of the conversion, temperature and pressure dependency from any combination of measurements. As a model-free identification method, it does not rely on a-priori assumptions about the kinetic model. The result vectors can be used to identify the kinetic parameters by means of model fitting for each variable independently.

The steps of the algorithm are described and its effectiveness is demonstrated by applying it to simulated datasets. The kinetic parameters could be recovered very accurately from the test data, also in the presence of noise.

Overall the higher order NPK-method is a very promising approach to derive kinetic models from experimental data with a minimum of a-priori assumptions about the reaction.


Peer Reviewed Scientific Journals | 2017

A hybrid of winddiesel technology with biomass-based Fischer-Tropsch synthesis

Nikparsa P, Rauch R, Mirzaei AA. A hybrid of winddiesel technology with biomass-based Fischer-Tropsch synthesis. Monatshefte für Chemie. 10 July 2017;1-10.

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The syngas mixture produced from biomass (bio-syngas) is characterized by a H2/CO molar ratio of 1.5 in this work, which is different from that of traditional syngas ratio of 2. Therefore a hybrid of winddiesel technology with bio-syngas conversion by Fischer–Tropsch synthesis (WD-FT) on a cobalt based catalyst was investigated, for the first time, using a slurry reactor. The result from feeding this technology is compared with the direct converting biomass derived synthetic gas to fuels via Fischer–Tropsch synthesis (BS-FT). Experiments were performed at different syngas composition (variation of H2/CO ratio), keeping the other parameters (temperature 230 °C; gas flow 5 Nm³/h, pressure 20 bar) constant. Comparison of the WD-FT with the BS-FT synthesis results displayed mass fraction of light hydrocarbons and higher catalytic stability and activity after 500 h. The olefin structures for the different product distributions, obtained from different reactions, are determined by ¹H NMR spectroscopy. Negligible amounts of iso-α-olefins were detected in the product of the WD-FT reaction. In the case of the alpha value, a slight change was observed between 0.93 and 0.92 for the BS-FT and WD-FT reaction.
 


Contributions to trade journals | 2013

A new innovative CFD-based optimisation method for biomass combustion plants

Shiehnejadhesar A, Schulze K, Scharler R, Obernberger I. A new innovative CFD-based optimisation method for biomass combustion plants. Biomass Bioenergy. 2013;53:48-53.

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In this paper, the work on the development and test of a basic design tool for the automatic performance of parameter studies for the optimisation of biomass combustion plants is presented. The model consists of parameterisation and optimisation routines linked with an in-house developed empirical packed bed combustion model as well as gas phase CFD models especially adapted for biomass grate furnaces. To test and verify the routine developed, it has been applied to the optimisation of a 180 kWth pilot-scale grate furnace. The main focus was on the minimisation of CO emissions and the pressure loss by changing the diameter and angle of the secondary air nozzles. The simulation results show that the time of the optimisation process can be reduced considerably by the automatic routine developed and the evaluation of several independent design parameters is possible. This new procedure forms an important milestone towards automatic CFD-based furnace and boiler optimisations in the future. © 2013 Elsevier Ltd.


Conference Papers | 2017

A novel approach for the implementation of TORrefaction in Residential and COMmunal heating Boilers (TORRECOMB)

Kourkoumpa DS, Kienzl N, Isemin R, Strasser C, Nikolopoulus N, Margaritis N, Panagiotis G. A novel approach for the implementation of TORrefaction in Residential and COMmunal heating Boilers (TORRECOMB). 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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Conference Papers | 2017

A Theoretical and Experimental Study of the Formation of Aromatic Hydrocarbons (BTX/PAH) as Soot Precursors from Biomass Pyrolysis Products

Mehrabian R, Shiehnejadhesar A, Bahramian H, Anca-Couce A, Sommersacher P, Hochenauer C, Scharler R. A Theoretical and Experimental Study of the Formation of Aromatic Hydrocarbons (BTX/PAH) as Soot Precursors from Biomass Pyrolysis Products. 25th European Biomass Conference & Exhibition (oral presentation). May 2017, Stockholm, Sweden.

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In this work a novel reaction mechanism for gas phase reactions has been developed to predict the formation of aromatic compounds from the pyrolysis products of woody biomass particles. The aromatic compounds are important for being main soot precursors as well as their toxic properties. The developed gas phase mechanism is validated with experimental data from literature as well as experimental data performed with a single particle reactor for three different pyrolysis temperatures, namely 550, 800 and 1000°C. A good agreement is achieved between model results and experimental data for the total yield of each main family of aromatic hydrocarbons, i.e. phenolics, BTXs and PAHs.


Other Presentations | 2012

Abbilden des instationären Betriebs eines Pelletkessel durch Messung und Simulation

Schnetzinger, R. Abbilden des instationären Betriebs eines Pelletkessel durch Messung und Simulation, Diploma Thesis, FH Oberösterreich, Wels, Austria, 2012.

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This thesis focuses on portraying the thermal behavior of a biomass pellet boiler through measurement and simulation. During operation the power of a pellet boiler changes depending on the heat demand. Detailed measurements were conducted to record this changing behavior of some boilers and estimate their levels of efficiencies. Subsequently a mathematical model was created to emulate boilers and their thermal performance without such measurements. The first part of this thesis deals with the description of the simulation model and the measurements which were carried out. Secondly, the verification of the model is discussed. For this verification simulation results of three different boilers are compared to measurement data and pictured in various diagrams. The last part of this thesis is about further simulations of these three boilers where the control units were emulated too. The model was built in the MATLAB/Simulink® environment and is generally based on
thermodynamic relationships and heat balances in a boiler. However, through constant comparison of the simulation results with the measurement data some parameters were adapted to fit the simulation to reality. Therefore this model is “semi-empirical” as physical correlations are included but some parameters were deduced from measurement. Following, the verification of the model is discussed through the comparison of measurement data and simulation results. For the verifications the boiler power, fuel mass flow as well as
the heat consumption were taken from the measurement data and set as input for the simulation. The calculated results show that the boiler model enables to portray the thermal behavior of the three boilers tested with only small divergences. At the end of this thesis it was attempted to model the control unit of the three boilers by analyzing the measurement data. Having a model for the control unit, the inputs from the measurement data are reduced to just two variables, the water inlet temperature and the water volume flow (heat consumption). The comparison of the calculated values to the measurement data shows slightly higher divergences than during the validation, especially where the simulated control unit does not behave like the real one. Through the simulation of further boilers the model could be continuously enhanced. In the future this “virtual boiler” should be used to test control algorithms of boiler control units to enhance their efficiencies.


Conference contributions | 2017

Abschätzung der Ertragssteigerung durch moderne Regelungsstrategien

Innerhofer P, Unterberger V, Gerardts B, Lichtenegger K, Gölles M. Abschätzung der Ertragssteigerung durch moderne Regelungsstrategien. 27. Symposium Thermische Solarenergie OTTI. Bad Staffelstein, Deutschland: 2017.

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Peer Reviewed Scientific Journals | 2017

Acid base interaction and its influence on the adsorption kinetics and selectivity order of aromatic sulfur heterocycles adsorbing on Ag-Al2O3

Neubauer R, Husmann M, Weinlaender C, Kienzl N, Leitner E, Hochenauer C. Acid base interaction and its influence on the adsorption kinetics and selectivity order of aromatic sulfur heterocycles adsorbing on Ag-Al2O3. Chemical Engineering Journal. 1 February 2017;309: 840-849.

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Adsorptive desulfurization is a promising technology to provide sulfur free fuels for fuel cell based power units. In this work the adsorption kinetics of three different aromatic sulfur heterocycles was studied for Ag-Al2O3. The influence of individual as well as competitive adsorption on the selectivity order was investigated by equilibrium and breakthrough experiments. In these experiments a jet-A1 fuel enriched with benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was used. The adsorption of aromatic sulfur heterocycles on Ag-Al2O3 proceeds via three different adsorption mechanisms. Within these mechanisms the π-interaction (π-Ag) and the direct sulfur-silver interaction (S-Ag) are significantly stronger in comparison to the acid base interaction (S-H). The results showed that the π-Ag and S-Ag interactions are the major adsorption mechanisms in the first stage, where film-diffusion limits the adsorption rate. In the second stage, the S-H interaction plays only an important role for BT, where intraparticle diffusion is the rate controlling step. The overall selectivity order was found to be BT > DBT > 4,6-DMDBT in the case of competitive adsorption for both equilibrium and breakthrough performance. The S-H contribution was related to incorporation of silver into blank γ-alumina, which significantly increased the overall acidity of the adsorbent.


Conference contributions | 2014

Active condensation in a 10MW heating plant - measurement results from the first heating season

Hebenstreit B, Höftberger E, Schwabl M, Lundgren J, Toffolo A. Active condensation in a 10MW heating plant - measurement results from the first heating season, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

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Contributions to trade journals | 2012

Acute systemic and lung inflammation in C57Bl/6J mice after intratracheal aspiration of particulate matter from small-scale biomass combustion appliances based on old and modern technologies

Uski OJ, Happo MS, Jalava PI, Brunner T, Kelz J, Obernberger I, Jokiniemi J, Hirvonen M-R. Acute systemic and lung inflammation in C57Bl/6J mice after intratracheal aspiration of particulate matter from small-scale biomass combustion appliances based on old and modern technologies. Inhalation Toxicology. 2012;24(14):952-965.

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Peer Reviewed Scientific Journals | 2015

Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield

Gruber-Brunhumer MR, Jerney J, Zohar E, Nussbaumer M, Hieger C, Bochmann G, Schagerl M, Obbard JP, Fuchs W, Drosg B. Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield. Algal Research. 01 November 2015;12:230-238.

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Conference contributions | 2018

Adaptive forecasting methods for the prediction of future solar yield of solar thermal plants and heat demand of consumers

Unterberger V, Nigitz T, Luzzu M, Innerhofer P, Muschick D, Gölles M. Adaptive forecasting methods for the prediction of future solar yield of solar thermal plants and heat demand of consumers. 5th International Solar District Heating Conference SDH. Graz, Austria: 2018.

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Conference Papers | 2018

Adaptive Methods for Energy Forecasting of Production and Demand of Solar Assisted Heating Systems

Unterberger V, Nigitz T, Luzzu M, Muschick D, Gölles M. Adaptive Methods for Energy Forecasting of Production and Demand of Solar Assisted Heating Systems., Proceeding of Papers Vol1, p170-181 International conference on time series and forecasting, Granada, Spain, September 19-21, 2018.

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Peer Reviewed Scientific Journals | 2016

Adsorptive Desulfurization: Fast On-Board Regeneration and the Influence of Fatty Acid Methyl Ester on Desulfurization and in Situ Regeneration Performance of a Silver-Based Adsorbent

Neubauer R, Weinlaender C, Kienzl N, Schroettner H, Hochenauer C. Adsorptive Desulfurization: Fast On-Board Regeneration and the Influence of Fatty Acid Methyl Ester on Desulfurization and in Situ Regeneration Performance of a Silver-Based Adsorbent. Energy and Fuels. 16 June 2016;30(6): 5174-5182.

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Adsorptive on-board desulfurization units require a high desulfurization and regeneration performance for a wide range of fuels to keep them small and ensure long maintenance intervals. A novel thermal regeneration strategy was investigated in this work, fulfilling all requirements for in situ on-board regeneration. In this strategy, a temperature-controlled flow rate (TCFR) of air was used to control the temperature inside the adsorber. With this dynamic approach, the regeneration time was reduced significantly in comparison to other thermal regeneration strategies. The novel regeneration strategy was tested using Ag–Al2O3 as an adsorbent to desulfurize a benzothiophen (BT)-enriched road diesel (300 ppmw of total sulfur). A commercial diesel containing fatty acid methyl ester (FAME) was used to evaluate the fuel flexibility regarding desulfurization and regeneration performance. In the case of 6.63 wt % FAME and 300 ppmw of sulfur, the breakthrough adsorption capacity of sulfur decreased from 1.04 to 0.17 mg/g. In TCFR regeneration experiments, the breakthrough adsorption capacity was restored to over 94% in the case of both fuels. Thereby, the Brunauer–Emmett–Teller (BET) surface area of the regenerated adsorbent decreased by only 1.5%, and negligible carbon deposits were detected.


Scientific Journals | 2018

Adsorptive on-board desulfurization over multiple cycles for fuel-cell-based auxiliary power units operated by different types of fuels

Neubauer, R, Weinlaender C, Kienzl N, Bitschnau B, Schroettner H, Hochenauer C. Adsorptive on-board desulfurization over multiple cycles for fuel-cell-based auxiliary power units operated by different types of fuels. Journal of Power Sources. 1 May 2018, 385: 45-54.

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On-board desulfurization is essential to operate fuel-cell-based auxiliary power units (APU) with commercial fuels. In this work, both (i) on-board desulfurization and (ii) on-board regeneration performance of Ag-Al2O3 adsorbent is investigated in a comprehensive manner. The herein investigated regeneration strategy uses hot APU off-gas as the regeneration medium and requires no additional reagents, tanks, nor heat exchangers and thus has remarkable advantages in comparison to state-of-the-art regeneration strategies. The results for (i) show high desulfurization performance of Ag-Al2O3 under all relevant operating conditions and specify the influence of individual operation parameters and the combination of them, which have not yet been quantified. The system integrated regeneration strategy (ii) shows excellent regeneration performance recovering 100% of the initial adsorption capacity for all investigated types of fuels and sulfur heterocycles. Even the adsorption capacity of the most challenging dibenzothiophene in terms of regeneration is restored to 100% over 14 cycles of operation. Subsequent material analyses proved the thermal and chemical stability of all relevant adsorption sites under APU off-gas conditions. To the best of our knowledge, this is the first time 100% regeneration after adsorption of dibenzothiophene is reported over 14 cycles of operation for thermal regeneration in oxidizing atmospheres.


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