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Peer Reviewed Scientific Journals | 2017

Influence of pellet length on performance of pellet room heaters under real life operation conditions

Wöhler M, Jaeger D, Reichert G, Schmidl C, Pelz SK. Influence of pellet length on performance of pellet room heaters under real life operation conditions. Renewable Energy. 1 May 2017;105: 66-75.

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Wood pellet combustion for heating is increasing in importance in Europe. However, the most commonly used heating appliances such as wood pellet stoves are responsible for emissions which could negatively affect human health. The emissions quality of pellet stoves is influenced by pellet properties and combustion phase characteristics. The goal of this study is to investigate the influence of pellet length on the performance of pellets stoves under real life operation conditions. Three softwood pellet samples were produced, differing only in length. Combustion tests with two different types of pellet stoves were performed in steady and non-steady combustion phases. Gaseous and particulate emissions as well as fuel mass flow were measured. Results show a reduced fuel mass flow (up to 36%) into the combustion chamber for long pellets compared to short pellets. The results of the combustion tests show a considerable influence of pellet length on the performance of both pellet stoves. For example, carbon monoxide emissions and particulate emissions of one stove in nominal load operation increased for long pellets compared to short pellets from 185 mg/m3 to 882 mg/m3, and from 27 mg/m3 to 37 mg/m3 respectively. Results also show a considerable influence of the combustion phase on the emissions level.


Conference Papers | 2017

Influence of sulfur components on the catalytic mixed alcohol synthesis based on wood gas derived from biomass steam

Binder, M., Rauch, R., Koch, M., Summers, M., Aichernig, C., and Hofbauer, H.: Influence of sulfur components on the catalytic mixed alcohol synthesis based on wood gas derived from biomass steam. In: Proceedings of the 25th European Biomass Conference and Exhibition, 12 - 15 June 2017, Stockholm, Sweden.

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Conference Papers | 2017

Innovative flexible grate solutions for future biomass combustion appliances

Feldmeier, S., Wopienka, E., Schwarz, M., Mehrabian Bardar, R.: Innovative flexible grate solutions for future biomass combustion appliances. (European Biomass Conference and Exhibition 2017, Stockholm).

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The energetic utilization of alternative fuels (short rotation coppice, miscanthus), agricultural by-products (straw, corn cobs) or biomass residues (nut shells, coffee grounds) becomes of increasing interest. Due to variations in fuel properties – and the ash content in particular – biomass fuels considerably influence the conditions in the combustion zone and especially in the fuel bed. Usually, state-of-the-art combustion appliances are optimized for a particular fuel quality and typically approved only for utilization of standardized wood pellets or wood chips. Research activities within the GrateAdvance project focus on fuel flexible grate technologies being capable of adapting conditions in the combustion zone by a systematic and targeted adjustment of grate parameters in order to minimize emissions and slagging problems, thus setting the basis for a new generation of biomass technologies. Moreover, a novel control concept will ensure optimal combustion conditions for any biomass fuel, and specifically adjust to relevant fuel properties.


Peer Reviewed Scientific Journals | 2017

Intelligent Heat Networks: First Results of an Energy-Information-Cost-Model

Lichtenegger K, Hoeftberger E, Schmidl C, Woess D, Proell T, Halmdienst C. Intelligent Heat Networks: First Results of an Energy-Information-Cost-Model. Sustainable Energy, Grids and Networks. September 2017;11: 1-12.

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Integrating additional renewable heat sources into district heating networks can have several beneficial effects, but it also requires more sophisticated control strategies than supply by only one central plant. In this article, we study the integration of prosumers (i.e. buildings which have both the capacity to produce and the need to consume energy, here heat) into heat distribution grids.

This study is performed with a simplified model, based on energy and information flows. The prosumers can act autonomously, based on a price communicated by the central heat plant. This price is determined based on the benefit for the network by additional heat feed-in and is regularly updated. This leads to an interlocking of a physical/technical and an economic feedback loop. The control parameters are optimized by using a stochastic optimization algorithm, based on simulation runs for one typical week in winter, spring and summer.

We compare the results with standard setups (heat network with only consumers, central heat generation and additional heat-producing building disconnected from the grid) and obtain an improvement concerning fuel consumption in most and concerning emissions in many situations. While economic benefits are achieved in most scenarios, it is a non-trivial task to construct a market model that distributes these benefits in a fair way between the central heat plant and the prosumers.


Peer Reviewed Scientific Journals | 2017

Investigations using a cold flow model of char mixing in the gasification reactor of a dual fluidized bed gasification plant

Kraft S, Kirnbauer F, Hofbauer H. Investigations using a cold flow model of char mixing in the gasification reactor of a dual fluidized bed gasification plant. Powder Technology. 1 July 2017;316: 687-696.

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This paper treats the mixing and movement of char in a dual fluidized bed (DFB) biomass gasification plant. In these plants such measurements are troublesome to perform, and so a cold flow model has been developed to investigate this topic. This cold flow model allows simulating the fluidization behaviour of the gasification reactor in the DFB plant in Güssing, Austria. The recirculation of the bed material is also possible, and can be easily controlled with a rotary valve. In the cold flow model, bronze is used as the bed material and polyethylene as the char. It is possible to take samples during operation to investigate the char concentration in the bed material recirculation stream. Experiments have shown that the char shows a flotsam behaviour since it is of low density. Furthermore, the investigations have shown that higher fluidization rates and higher bed material recirculation rates enhance the char mixing and increase the char concentration in the recirculation stream. It was found that doubling the overall char concentration in the system does not lead to a doubling of the char concentration in the bed material recirculation stream. Furthermore, the influence of the bed height in the gasification reactor was investigated. It was found that higher bed heights lead to lower char concentrations in the recirculation stream. These initial investigations revealed that much is still unknown about DFB plants, but the knowledge of the behaviour of the different types of particles in the bubbling bed of the gasification reactor helps to further improve and develop the DFB technology.


Peer Reviewed Scientific Journals | 2017

Long Term Durability and Safety Aspects of Oxidizing Honeycomb Catalysts Integrated in Firewood Stoves

Reichert G, Schmidl C, Haslinger W, Stressler H, Sturmlechner R, Schwabl M, Kienzl N, Hochenauer C. Long Term Durability and Safety Aspects of Oxidizing Honeycomb Catalysts Integrated in Firewood Stoves. Biomass and Bioenergy. August 2017;

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Critical heating operating conditions, as emulated in the safety test series, showed that temperatures below 400 °C at the integrated catalysts result in deposited agglomerations on the flow cross-section area of the catalyst's surface and in the risk of increased pressure drops. The deposited material of safety tests consisted predominantly of carbonaceous components with a share of around 120 g kg−1 of OC and 280–450 g kg−1 of EC. The oxidation potential of deposited carbonaceous material by higher temperatures was confirmed by a minor share of EC and OC (<50 g kg−1) on the catalyst's surface when a heating cycle with five batches was performed. Concluding a sufficient heating-up of catalyst integrated stoves is necessary to avoid deposition of carbonaceous agglomerations.

The long term tests resulted in deposited agglomerations of mineral particles on the catalyst's surface of both types of catalysts. The metallic honeycomb catalyst was more sensitive regarding blocking which was indicated by total blocked cells and a significant increase of pressure drop by 5.3 Pa. Due to the effect of agglomerated particles gaseous emissions increased significantly (CO around 300%, OGC around 45%) whereas PM emissions were reduced by 63%. The regeneration of catalyst performance was almost completely achieved by cleaning the catalyst with water and pressured air. For processing of blocking the open diameter of cells of the honeycomb catalysts play a relevant role. Therefore, in terms of real-life applicability the ceramic honeycomb catalyst seems to be more suitable compared to the metallic honeycomb catalyst.


Conference contributions | 2017

Marktmodellentwicklung für die dezentrale Wärmebereitstellung in Wärmenetzen

Leitner A, Lichtenegger K, Mair C, Höld M. Marktmodellentwicklung für die dezentrale Wärmebereitstellung in Wärmenetzen. 10. Internationale Energiewirtschaftstagung, TU Wien, 2017.

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Peer Reviewed Scientific Journals | 2017

Maximizing the production of butyric acid from food waste as a precursor for ABE-fermentation

Stein UH, Wimmer B, Ortner M, Fuchs W, Bochmann G. Maximizing the production of butyric acid from food waste as a precursor for ABE-fermentation. Science of The Total Environment. 15 November 2017;598: 993-1000.

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Conference contributions | 2017

Microgrids and the Regional Balance of Supply and Demand in the Electricity and Heating Sector

Stadler M, Mair C, Zellinger M, Lichtenegger K, Haslinger W, Temper M, Moser A, Carlon E, Muschick D, Gölles M. Microgrids and the Regional Balance of Supply and Demand in the Electricity and Heating Sector. 20. Österreichischer Biomassetag, Windischgarsten, 14. - 15. November 2017.

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Other publication | 2017

Microgrids und dezentrale Energieerzeugung

Stadler M.,Carlon E., Gölles M., Haslinger W., Lichtenegger K., Mair C., Moser A., Muschick D., Zellinger M. Microgrids und dezentrale Energieerzeugung. Wasser Cluster Lunz/See Österreich, 21. September 2017.

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Other publication | 2017

Mikro-Netze und die regionale Balance von Erzeugung und Verbrauch im Strom- und Wärmebereich

Stadler M, Mair C, Zellinger M, Lichtenegger K, Haslinger W, Temper M, Moser A, Carlon E, Muschick D, Gölles M. Mikro-Netze und die regionale Balance von Erzeugung und Verbrauch im Strom- und Wärmebereich. Impulsreferat 20. Österreichischer Biomassetag. Sektorkopplung & Flexibilisierung. Windischgarsten, Österreich. 14. November 2017.

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Other Presentations | 2017

Model-based control of hydronic networks using graph theory

Muschick D, Unterberger V, Gölles M. Model-based control of hydronic networks using graph theory. Steirische Seminar über Regelungstechnik und Prozessautomatisierung / Styrian Workshop on Automatic Control. September 2017.

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Reviewed Conference Papers | 2017

Model-Based Control Strategies for an Efficient Integration of Solar Thermal Plants Into District Heating Grids

Unterberger V, Muschick D, Gölles M. Model-Based Control Strategies for an Efficient Integration of Solar Thermal Plants Into District Heating Grids. ISES Solar World Congress 2017. 29.10-02.11.2017. Abu Dhabi, United Arab Emirates.

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The integration of solar thermal plants into district heating grids requires advanced control strategies in order to utilize the full potential in terms of efficiency and least operating effort. State-of-the-art control strategies cannot completely fulfil this since they are not able to consider the physical characteristics of the different components, nor do they take information on future conditions and requirements into account properly. A promising attempt for improvement is the application of model-based control strategies together with practicable forecasting methods for both the solar yield as well as the heat demand. This contribution will present the results of several projects performed on the development of suitable mathematical models, forecasting methods and control strategies relevant for the integration of solar thermal plants into district heating grids.


Peer Reviewed Scientific Journals | 2017

Modelling heat of reaction in biomass pyrolysis with detailed reaction schemes

Anca-Couce A, Scharler R. Modelling heat of reaction in biomass pyrolysis with detailed reaction schemes. Fuel. 15 October 2017;206: 572-579.

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Primary devolatilization and the exothermic heterogeneous secondary charring of the primary volatiles need to be described in a consistent manner in order to correctly predict the heat of reaction of biomass pyrolysis. Detailed reaction schemes can currently predict mass loss and product composition of biomass pyrolysis with good accuracy, but have a weakness in the description of the heat of reaction. In this work it is shown for the first time that including secondary charring reactions a detailed reaction scheme can predict the evolution of the heat of pyrolysis for different conditions. The enthalpy of reaction is calculated for each reaction as the difference between the net calorific value of reactants and products. The presented model is able to describe the heat evolution in micro-TGA-DSC experiments conducted without a lid, where pyrolysis is endothermic, and with a lid, where secondary reactions are enhanced and the global heat of reaction shifts to exothermic. Furthermore, when it is coupled to a particle model, it correctly describes single particle pyrolysis experiments conducted with beech spheres where there is a remarkably exothermic peak in the centre temperature.


Conference Papers | 2017

Modellprädiktive Regelung eines solar-und biomassebasierten Fernwärmenetzes

Moser A, Muschick D, Lichtenegger K, Gölles M, Hofer A. Modellprädiktive Regelung eines solar- und biomassebasierten Fernwärmenetzes. Zukunft der Gebäude: digital - dezentral - ökologisch. 23 Nov 2017; Leykam;16:151-159.

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The use of renewable-energy-based heat producers within district heating grids is getting more and more popular. In order to benefit from the advantages and compensate for the different disadvantages of the various types of heat producers powered by renewable energy sources like biomass, solar energy or waste heat, a combination of these systems could be favoured over using, for example, only one main biomass-based boiler. Furthermore , in many cases, the additional use of buffer storages is necessary to fully benefit from the use of these kinds of heat producers. A major challenge with such multi-producer heating grids is the cost optimal management of all heat producers and buffer storages. Therefore , a high-level control strategy is necessary, which is able to plan ahead the use of slowly reacting and/or weather dependent heat producers while minimizing operational costs and pollutant emissions. This article shows the development of a linear model predictive controller (MPC) for a district heating grid with several (renewable) decentralized heat producers and heat storages. In order to provide the MPC with the required forecast of the future heat demand, an adaptive load forecasting method has been designed. Additionally, in order to be able to incorporate solar panels, the MPC needs to have a forecast of their possible future heat output. Therefore, a physically motivated solar yield forecasting method has been designed. The required prediction models for the MPC were represented by so-called mixed logical dynamical (MLD) system models. MLD system models combine the modelling power of discrete state system models (finite state machines) and discrete time system models by the extension of the regular linear state-space system model approach with integer and continuous auxiliary variables and linear inequality constraints. The occurrence of both integer and continuous variables within the resulting optimization problem of the MPC leads to a mixed-integer linear program (MILP), which can be solved efficiently using modern MILP solvers. The resulting control strategy is tested in a thermo-hydraulic simulation environment of an actual small-scale multi-producer district heating grid consisting of a medium-scale wood chip boiler with buffer storage, a solar collector with buffer storage and a high temperature heat pump, an oil boiler and 25 heat consumers. Additionally, a state observer was designed and connected with the MPC in order to detect control errors and to incorporate feedback from the heat producers and the buffer storages. The simulations have indicated that the designed MPC and the state observer work properly. Therefore, these elements have been implemented on-site on the actual heating grid, with the first test run scheduled for October 2017.
Modellprädiktive Regelung eines solar-und biomassebasierten Fernwärmenetzes | Request PDF. Available from: https://www.researchgate.net/publication/321314304_Modellpradiktive_Regelung_eines_solar-und_biomassebasierten_Fernwarmenetzes [accessed Feb 21 2018].


Conference Papers | 2017

Nitrogen Assessment in Small Scale Biomass Heating Systems

Enigl M, Strasser C, Hochbichler E, Schmidl C. Nitrogen Assessment in Small Scale Biomass Heating Systems. 25th European Biomass Conference & Exhibition (Poster). June 2017, Stockholm, Sweden.

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Conference Papers | 2017

Novel concepts for CO2 utilisation to produce value added products

Sonnleitner A, Dißauer C, Martini S, Drosg B, Meixner K, Rachbauer L, Lazarova Z, Herwig C, Kinger G, Kofler I, Strasser C. Novel concepts for CO2 utilisation to produce value added products. 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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Peer Reviewed Scientific Journals | 2017

Optimisation of continuous gas fermentation by immobilisation of acetate-producing Acetobacterium woodi

Steger, F, Rachbauer L, Windhagauer M, Montgomery LFR, Bochmann G. Optimisation of continuous gas fermentation by immobilisation of acetate-producing Acetobacterium woodi. Anaerobe. August 2017;46: 96-103

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Other Publications | 2017

Optimisation of continuous gas fermentation by immobilisation of acetate-producing Acetobacterium woodii.

Steger, F, Rachbauer L, Windhagauer M, Montgomery LFR, Bochmann G. Optimisation of continuous gas fermentation by immobilisation of acetate-producing Acetobacterium woodii. Anaerobe. Available online 22 June 2017

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Conference Papers | 2017

Optimisation of the post-consumer and demolition wood supply and value chain

Dißauer C, Kienzl N, Kunter A, Meirhofer M, Pointner C, Schwarzbauer P, Sommersacher P, Strasser C, Wellacher M. Optimisation of the post-consumer and demolition wood supply and value chain. 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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Peer Reviewed Scientific Journals | 2017

Overcoming the bottlenecks of anaerobic digestion of olive mill solid waste by two-stage fermentation

Stoyanova E, Lundaa T, Bochmann G, Fuchs W. Overcoming the bottlenecks of anaerobic digestion of olive mill solid waste by two-stage fermentation. Environmental Technology (United Kingdom). 16 February 2017;38(4): 394-405.

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Peer Reviewed Scientific Journals | 2017

Particulate emissions from modern and old technology wood combustion induce distinct time-dependent patterns of toxicological responses in vitro.

Happo MS, Hirvonen MR, Uski O, Kasurinen S, Kelz J, Brunner T, Obernberger I, Jalava PI. Particulate emissions from modern and old technology wood combustion induce distinct time-dependent patterns of toxicological responses in vitro. Toxicology in Vitro. Volume 44, October 2017, Pages 164-171

Toxicology in Vitro.

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Toxicological characterisation of combustion emissions in vitro are often conducted with macrophage cell lines, and the majority of these experiments are based on responses measured at 24 h after the exposure. The aim of this study was to investigate how significant role time course plays on toxicological endpoints that are commonly measured in vitro. The RAW264.7 macrophage cell line was exposed to PM1 samples (150 μg/ml) from biomass combustion devices representing old and modern combustion technologies for 2, 4, 8, 12, 24 and 32 h. After the exposure, cellular metabolic activity, cell membrane integrity, cellular DNA content, DNA damage and production of inflammatory markers were assessed. The present study revealed major differences in the time courses of the responses, statistical differences between the studied samples mostly limiting to differences between modern and old technology samples. Early stage responses consisted of disturbances in metabolic activity and cell membrane integrity. Middle time points revealed increases in chemokine production, whereas late-phase responses exhibited mostly increased DNA-damage, decreased membrane integrity and apoptotic activity. Altogether, these results implicate that the time point of measurement has to be considered carefully, when the toxicity of emission particles is characterised in in vitro study set-ups.


Conference Papers | 2017

Performance of a mixed alcohol synthesis lab-scale process chain operated with wood gas from dual fluidized bed biomass steam gasification

Binder M, Weber G, Rauch R, Hofbauer H. Performance of a mixed alcohol synthesis lab-scale process chain operated with wood gas from dual fluidized bed biomass steam gasification. 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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Reviewed Conference Papers | 2017

Performance of a water gas shift unit processing tar-rich product gas from a commercial dual fluidized bed biomass steam gasification plant which operates at partial load

Kraussler M, Binder M, Hofbauer H. Performance of a water gas shift unit processing tar-rich product gas from a commercial dual fluidized bed biomass steam gasification plant which operates at partial load. International Journal of Oil, Gas and Coal Technology. 2017;14(1-2): 32-48.

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In this paper, the performance of a water gas shift unit processing product gas from a commercial dual fluidised bed biomass steam gasification plant is studied. The experiments were carried out during a partial load operation of the gasification plant. In order to investigate a water gas shift process, a water gas shift unit, located at the site of the gasification plant in Oberwart, Austria, was used. The water gas shift unit consisted of three reactors in series filled with a commercial Fe'Cr-based catalyst and was operated with tar-rich product gas. No performance decrease of the water gas shift unit was observed during the partial load operation of the gasification plant. Furthermore, a CO conversion of 92% and a GCMS tar reduction of about 30% were reached. In addition, it was found that partial load operation of the gasification plant did not negatively affect the performance of the water gas shift unit.


Conference Papers | 2017

Polygeneration of hydrogen and a gas mixture composed of H2 and CH4 via sorption enhanced reforming of biomass

Kraussler M, Priscak J, Benedikt F, Hofbauer H. Polygeneration of hydrogen and a gas mixture composed of H2 and CH4 via sorption enhanced reforming of biomass. 25th European Biomass Conference & Exhibition (oral presentation). June 2017, Stockholm, Sweden.

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