Filter

Sortierung Titel Year

Publikationen


Other Presentations | 2014

Modellierung und Regelung eines Pufferspeichers in Kombination mit einer Biomassefeuerung

Hemmer, J. Modellierung und Regelung eines Pufferspeichers in Kombination mit einer Biomassefeuerung, Master Thesis, Technische Universität Graz, Graz, Austria, 2014.

Details

Die vorliegende Arbeit widmet sich der Herleitung mathematischer Simulationsmodelle eines Pufferspeichers, eines Solarkollektors sowie eines Plattenwärmeübertragers. Dabei wird das Simulationsmodell des Pufferspeichers anhand eines am Markt verfügbaren Pufferspeichers entwickelt. Die mathematischen Beschreibungen der Simulationsmodelle basieren auf einer partiellen Differentialgleichung zur Beschreibung der Wärmeübertragung in einem durchströmten zylindrischen Rohr. Nach dem Erhalt der mathematischen Modelle werden diese mit einem impliziten Lösungsverfahren numerisch gelöst. Anschließend werden die experimentell zu ermittelnden Parameter des Pufferspeichermodells anhand gezielt durchgeführter Versuche bestimmt. Nach dem Ermitteln der Parameter wird das Simulationsmodell des Pufferspeichers mit einem weiteren Versuch experimentell verifiziert. Schlussendlich bildet das mathematische Modell des Pufferspeichers den untersuchten Pufferspeicher sehr zufriedenstellend ab, womit ein Simulationsmodell vorliegt, das gezielte Untersuchungen ohne aufwändige Versuche ermöglicht. Abschließend wird eine Regelung für die Wärmeübertragung aus dem Solarkollektor in den Pufferspeicher entwickelt. Dabei werden zwei in der Praxis übliche Verfahren untersucht. Bei der ersten Variante erfolgt die Übertragung der Wärme in den Pufferspeicher über ein im Pufferspeicher integriertes Solarregister. Bei der zweiten Variante erfolgt die Übertragung der Wärme über einen Plattenwärmeübertrager vom Wasser-Frostschutzgemisch auf Wasser, welches dann direkt in den Pufferspeicher eingespeist wird. Als Reglerstruktur wird in beiden Fällen ein Standard-Regelkreis mit einer statischen Vorsteuerung verwendet. Anhand von Simulationsstudien werden zunächst die Parameter des PI-Reglers festgelegt und in weiterer Folge die mit der jeweiligen Variante resultierenden Temperaturverläufe des Wassers im Pufferspeicher untersucht und gegenübergestellt. Dabei stellt sich heraus, dass die Temperatur des Wassers im Pufferspeicher, bei gleich bleibender Strahlungsstromdichte der Solarstrahlung Igauf den Solarkollektor, die gewünschte Solltemperatur bei Wärmeübertragung mittels Plattenwärmeübertrager schneller erreicht, als bei Wärmeübertragung durch das Solarregister. Darüber hinaus ermöglicht die Verwendung des Plattenwärmeübertragers eine Schichtung der Temperatur des Wassers im Pufferspeicher und somit eine Speicherung der Wärme auf einen höheren Temperaturniveau.


Reviewed Conference Papers | 2014

Multi-physics modelling of packed bed biomass combustion

Mehrabian R, Shiehnejadhesar A, Scharler R, Obernberger I. Multi-physics modelling of packed bed biomass combustion. Fuel. 2014;122:164-78.

External Link

Details

A transient 3D model for two main zones, namely the fuel bed and the freeboard, of biomass packed bed combustion systems was developed. It integrates the models for the biomass conversion sub-processes and solves the governing equations for the gas and solid phase and their interactions. The intra-particle gradients are included by considering the biomass particles as thermally thick particles. The shrinkage of the packed bed and the variations of the bed porosity due to the uneven consumption of the fuel are taken into account. Detailed kinetic mechanisms are used for the simulation of homogeneous gas phase reactions. To verify the model and to increase the understanding of packed bed combustion, laboratory-scale fixed-bed batch experiments have been performed in a reactor with 9.5 cm diameter and 10 cm length. The model performance was extensively validated with gas phase measurements (CO, CO2, CH4, H2, H2O and O2) above the fuel bed, temperatures at different heights in the bed and in the freeboard, and the propagation rate of reaction front. The simulation results are in a good agreement with the measured values. © 2014 Elsevier Ltd. All rights reserved.


Conference contributions | 2014

Off-gassing – Safety issues related with harmful emissions from wood pellets

Emhofer W. Second International Workshop on Pellet Safety “Off-gassing – Safety issues related with harmful emissions from wood pellets”, 5th of May, Fügen, Austria, 2014.

Details


Conference contributions | 2014

Off-gassing –Safety issues related with emissions from wood pellets along the pellet supply chain

Emhofer W, et al. Pellets Workshop ” Off-gassing –Safety issues related with emissions from wood pellets along the pellet supply chain” (held held during the Central European Biomass Conference 2014), 15th-18th of January, Graz, Austria, 2014.

Details


Conference contributions | 2014

Optimising the heating system of a low energy house

Rimoldi M, Carlon E. Optimising the heating system of a low energy house, Word Sustainable Energy Days next 2014, 26th-28th of February 2014, Wels, Austria.

Details


Other Presentations | 2014

Pellet off-gassing during storage: The impact of storage conditions and type of source material

Meier, F. Pellet off-gassing during storage: The impact of storage conditions and type of source material, Master Thesis, University of Natural Resources and Life Sciences Vienna, Vienna, Austria, 2014.

Details


Conference contributions | 2014

Performances of a non-sulfided CoMo/SiO2-Al2O3 hydrocracking catalyst used in BtL Technology

Sauciuc A, Ganea R, Dumitrescu L, Rauch R, Hofbauer H. Performances of a non-sulfided CoMo/SiO2-Al2O3 hydrocracking catalyst used in BtL Technology, 4th International Symposium on Gasification and its Applications (iSGA-4) 2014, 2nd-5th of September 2014, Vienna, Austria.

Details


Conference contributions | 2014

Price cointegration in the Austrian wood fuel market,

Kristöfel C, Morawetz UB, Schmid E, Strasser C. Price cointegration in the Austrian wood fuel market, 22nd European Biomass Conference 2014, 23rd-26th of June 2014, Hamburg, Germany. p 1330-1335.

Details

The wood fuel market is connected to the forest­based industry in various ways: the sawmill by­ products such as sawdust and wood chips are usually used as raw material in the panel, pulp and paper industry and are increasingly pelletized to supply the energy commodity market. Hence, the question arises whether or not prices of these woody biomass commodities are integrated. Threshold cointegration and asymmetric error correction models are used to analyze the price dynamics between roundwood, wood pellets and sawmill by­ products. Results indicate that a statistical significant price transmission between sawmill by­products and wood pellets, but wood pellet and roundwood prices are not integrated. The price transmission between wood pellets and sawdust as well as wood chips is asymmetric. The Granger Causality test reveals that the prices of sawdust and wood chips depend on the price of wood pellets.


Conference contributions | 2014

Promotion of bioenergy initiatives in Centru Region, Romania

Kristöfel C, Ehrig R, Strasser C. Promotion of bioenergy initiatives in Centru Region Romania, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details


Conference contributions | 2014

Promotion of successful bioenergy initiatives in Eastern Europe

Kristöfel C. Promotion of successful bioenergy initiatives in Eastern Europe, Word Sustainable Energy Days 2014, 26th-28th of February 2014, Wels, Austria. (visual presentation)

Details


Contributions to trade journals | 2014

Quantitation of aging products formed in biodiesel during the Rancimat accelerated oxidation test

Flitsch S, Neu PM, Schober S, Kienzl N, Ullmann J, Mittelbach M. Quantitation of aging products formed in biodiesel during the Rancimat accelerated oxidation test. Energy and Fuels. 2014;28(9):5849-56.

External Link

Details

Biodiesel (rapeseed oil methyl ester) was aged in a Rancimat device at a temperature of 110°C and an air flow of 10 L/h. Time-resolved analyses applying gas chromatography-flame ionization detection, gas chromatography-mass spectrometry, and ion-exchange chromatography on the formation of aging products were performed. Formic and acetic acid, fatty acids with chain lengths from 5 to 18 carbon atoms, fatty acid methyl esters, and epoxides were quantified. After 12 h of aging, the concentrations of formic and acetic acid were 5600 ± 80 and 1360 ± 80 mg/kg, respectively. Fatty acid concentrations were in the range of <18-4200 mg/kg after 18 h of aging. Linoleic acid methyl ester and linolenic acid methyl ester (19 and 9.1 mass % of the non-aged fuel) were shown to be fully decomposed after 24 and 18 h of aging, respectively. After 51 h of aging, the concentration of oleic acid methyl ester (63 mass % of the non-aged fuel) decreased to 2.2 mass % and trans-epoxy stearic acid methyl ester and cis-epoxy stearic acid methyl ester reached concetrations of 5.9 and 0.7 mass %, respectively. The fuel composition shows only minor changes in early stages of aging, and a strong timely correlation of the formation of aging products with the end of the induction period of fuel was observed. © 2014 American Chemical Society.


Peer Reviewed Scientific Journals | 2014

Reducing the risk of foaming and decreasing viscosity by two-stage anaerobic digestion of sugar beet pressed pulp

Stoyanova E, Forsthuber B, Pohn S, Schwarz C, Fuchs W, Bochmann G. Reducing the risk of foaming and decreasing viscosity by two-stage anaerobic digestion of sugar beet pressed pulp. Biodegradation. 2014;25(2):277-89.

External Link

Details

Anaerobic digestion (AD) of sugar beet pressed pulp (SBPP) is a promising treatment concept. It produces biogas as a renewable energy source making sugar production more energy efficient and it turns SBPP from a residue into a valuable resource. In this study one- and two-stage mono fermentation at mesophilic conditions in a continuous stirred tank reactor were compared. Also the optimal incubation temperature for the pre-acidification stage was studied. The fastest pre-acidification, with a hydraulic retention time (HRT) of 4 days, occurred at a temperature of 55 °C. In the methanogenic reactor of the two-stage system stable fermentation at loading rate of 7 kg VS/m3 d was demonstrated. No artificial pH adjustment was necessary to maintain optimum levels in both the pre-acidification and the methanogenic reactor. The total HRT of the two-stage AD was 36 days which is considerably lower compared to the one-stage AD (50 days). The frequently observed problem of foaming at high loading rates was less severe in the two-stage reactor. Moreover the viscosity of digestate in the methanogenic stage of the two-stage fermentation was in average tenfold lower than in the one-stage fermentation. This decreases the energy input for the reactor stirring about 80 %. The observed advantages make the two-stage process economically attractive, despite higher investments for a two reactor system. © 2013 Springer Science+Business Media Dordrecht.
 


Conference contributions | 2014

Residential Wood Combustion (RWC) -Investigation of user behavior and operating conditions regarding stoves and their impact on emissions and efficiency

Reichert G, Schmidl C, Haslinger W, Moser W, Aigenbauer S, Figl F, Wöhler M. Residential Wood Combustion (RWC) -Investigation of user behavior and operating conditions regarding stoves and their impact on emissions and efficiency, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details

 


Conference contributions | 2014

Rolle und Potenzial der Bioenergie für die Wärmeversorgung der Zukunft

Haslinger W. Rolle und Potenzial der Bioenergie für die Wärmeversorgung der Zukunft, Technologiegespräche Alpbach 2014, 13th-29th of August 2014, Alpbach, Austria.

Details


Other Presentations | 2014

Scenedesmus obliquus as Source for Biogas: Anaerobic Digestion of Untreated and Pre-treated Biomass.

Gruber M, Zohar E, Jerney J, Bochmann G, Obbard JP, Schagerl M, Fuchs W, Drosg B. Scenedesmus obliquus as Source for Biogas: Anaerobic Digestion of Untreated and Pre-treated Biomass, 15. Tagung der Sektion Phykologie der DGB 2014, 23rd-26th of February 2014, Stralsund, Germany.

Details


Peer Reviewed Scientific Journals | 2014

Seeing about soil — management lessons from a simple model for renewable resources

Lichtenegger K, Schappacher W. Seeing about soil — management lessons from a simple model for renewable resources. International Journal of Modern Physics C. 2014;25(8).

External Link

Details

Employing an effective cellular automata model, we investigate and analyze the build-up and erosion of soil. Depending on the strategy employed for handling agricultural production, in many cases we find a critical dependence on the prescribed production target, with a sharp transition between stable production and complete breakdown of the system.

Strategies which are particularly well-suited for mimicking real-world management approaches can produce almost cyclic behavior, which can also either lead to sustainable production or to breakdown.

While designed to describe the dynamics of soil evolution, this model is quite general and may also be useful as a model for other renewable resources and may even be employed in other disciplines like psychology.


Conference contributions | 2014

Sicherheit bei der Lagerung von Pellets

Emhofer W. Sicherheit bei der Lagerung von Pellets, Highlights der Energieforschung VIII - Erneuerbares Heizen und Kühlen 2014, 11th of July 2014, Vienna, Austria

Details


Conference contributions | 2014

Status fortschrittlicher Biokraftstoffe

Bacovsky D. Status fortschrittlicher Biokraftstoffe, 7. EID Kraftstoff-Forum 2014, 18th-19th of March 2014, Hamburg, Germany

Details


Contributions to trade journals | 2014

Strategy for the application of novel characterization methods for biomass fuels: Case study of straw

Obernberger I. Strategy for the application of novel characterization methods for biomass fuels: Case study of straw. Energy and Fuels. 2014;28(2):1041-52.

External Link

Details

Because of an increasing interest in the utilization of new and in terms of combustion-related properties rather unknown biomass fuels in heat and power production, advanced fuel characterization tools are gaining rising interest. Currently, ongoing research and development (R&D) focuses on a better and more precise description of the combustion properties of specific biomass fuels by applying new/advanced analysis methods and modeling tools. These novel characterization methods cover combustion tests in specially designed lab reactors, special fuel indices for biomass fuels, and the dedicated application of high-temperature equilibrium calculations. In this paper, a strategy is presented how the information gained from different advanced fuel characterization methods can be combined to characterize a fuel regarding its combustion behavior in a novel way. By means of this strategy, relevant qualitative and quantitative information regarding the ash-melting behavior, aerosol, SOx, HCl, and NOx emissions to be expected, and high-temperature corrosion risks can be gained. In addition, the approach can also be used for the evaluation of additives and fuel blending as measures to improve specific combustion properties. The results show that a much better and clearer picture about the combustion properties of a specific biomass fuel can be provided than by conventional approaches (such as wet chemical analysis or other standardized methods). The results can be used for the preliminary design of plants as well as for evaluation of the applicability of a specific technology for a certain biomass fuel or fuel spectrum. Moreover, they can be applied in combination with computational fluid dynamics (CFD) simulations for the detailed design and evaluation of furnaces and boilers. © 2014 American Chemical Society.


Conference contributions | 2014

Synergies of Wastewater and Microalgae Cultivation

Sonnleitner A, Bacovsky D, Bochmann G, Drosg B, Schagerl M. Synergies of Wastewater and Microalgae Cultivation, Word Sustainable Energy Days next 2014, 26th-28th of February 2014, Wels, Austria.

Details

Current international research results identify microalgae as a new and promising feedstock for the global energy supply chain. A novel concept to reduce costs and cover the need of water and nutrients is the combination of wastewater treatment and microalgae cultivation. In Austria in particular brewery and dairy effluents as well as municipal wastewater would be suitable for algae cultivation. Cultivation systems practical for the use of wastewater are High Rate Algal Ponds (open system, suspended culture), Algal Turf Scrubbers (open system, immobilized culture) and Photobioreactors (closed systems, suspended culture). The cultivation of microalgae in general and the special case of wastewater as nutrient source face a variety of challenges either concerning the accumulation of microalgal cells in wastewater (upstream process) or their removal and processing (downstream process). Taking a look at the whole production chain shows that for effluents of breweries, dairies
and smale-scale municipal wastewater no feasible concept for the combination of microalgae cultivation and wastewater treatment can be designed. A promising production concept for large-scale municipal wastewater treatment plants are HRAPs or biofilm production in ATS systems for energetic and material pathways. Various R&D challenges are to overcome to lead to an optimization and further development of technologies for combined wastewater treatment and microalgae cultivation in Austria.


Peer Reviewed Scientific Journals | 2014

Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers

Hebenstreit B, Schnetzinger R, Ohnmacht R, Höftberger E, Lundgren J, Haslinger W, et al. Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers. Biomass Bioenergy. 2014;71:12-22.

External Link

Details

An active condensation system for the heat recovery of biomass boilers is evaluated. The active condensation system utilizes the flue gas enthalpy exiting the boiler by combining a quench and a compression heat pump. The system is modelled by mass and energy balances. This study evaluates the operating costs, primary energy efficiency and greenhouse gas emissions on an Austrian data basis for four test cases. Two pellet boilers (10kW and 100kW) and two wood chip boilers (100kW and 10MW) are considered. The economic analysis shows a decrease in operating costs between 2% and 13%. Meanwhile the primary energy efficiency is increased by 3-21%. The greenhouse gas emissions in CO2 equivalents are calculated to 15.3-27.9kg MWh-1 based on an Austrian electricity mix. The payback time is evaluated on a net present value (NPV) method, showing a payback time of 2-12 years for the 10MW wood chip test case. © 2014 Elsevier Ltd.


Contributions to trade journals | 2014

The Biomass Technology Roadmap of the RHC-Platform: Priorities for high efficient large-scale CHP units

Grammelis P, Goodwin N, Alakangas E, Haslinger W, Karampinis E. The Biomass Technology Roadmap of the RHC-Platform: Priorities for high efficient large-scale CHP units. VGB PowerTech. 2014;6:74-79.

Details

Die europäische Technologie-Plattform für Heizen und Kühlen mit erneuerbaren Energien (RHC-Plattform, www.rhc-platform.org) fördert die Forschung und Entwicklung bei der Wärme- und Kälteproduktion aus erneuerbaren Energiequellen in der EU. Die verschiedenen Endanwendungen (Strom und/oder Bereitstellung von Wärme, Kraftstoff) setzen eine Verdoppelung der Biomassenutzung voraus, um die 20-20-20-Ziele der EU zu erreichen. Neue Ressourcen müssen erschlossen, mobilisiert und der Wirkungsgrad der Umwandlungsprozesse gesteigert werden. In Biomasse-Heizkraftwerken sowie Heizwerken werden derzeit mehr als ein Drittel des gesamten Biomasseaufkommens eingesetzt. Dies führt zu neuen, gemeinsamen Herausforderungen für den Strom- und Wärmesektor.
Das Biomasse-Panel der RHC-Plattform hat Schwerpunkte für Forschung und Entwicklung definiert, um bestimmte Kennzahlen für Biomassewertschöpfungsketten zu erreichen. Der vorliegende Beitrag stellt die Prioritäten für die Bestandteile der Wertschöpfungsketten vor, die relevant für den Strombereich sind:
a) nachhaltige und kosten-effiziente Biomasseversorgungsketten, b) thermisch behandelte Biomasse-Brennstoffe und c) hoch-effiziente KWK-Anlagen.
Herausforderungen für den Anlagenbetrieb sind Brennstoffflexibilität, Wirkungsgraderhöhung über den vollen Lastbereich, Betrieb mit variablen Brennstoffen und Qualitäten bei variablen Lastzuständen, höhere Betriebsparameter für Dampf und andere Wärmeträger, höhere Anlagenverfügbarkeit, Reduktion von unerwünschten gas- und partikelförmigen Emissionen und schließlich die Ascheverwertung.
 


Conference contributions | 2014

Thermal simulation of a pellet boiler and a heat storage tank for future control strategies

Schnetzinger R, Musumarra I, Hebenstreit B, Lichtenegger K, Schwarz M, Höftberger E. Thermal simulation of a pellet boiler and a heat storage tank for future control strategies, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details


Other Presentations | 2014

Thermo-chemical pre-treatment of brewers' spent grains

Gorter S, Rachbauer L, Scheidl S, Gabauer W, Ortner M, Bochmann G. Thermo-chemical pre-treatment of brewers' spent grains, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details


Conference contributions | 2014

Torrefied pellets – influence of torrefaction on pellet characteristics and combustion behaviour

Pointner C, Schmutzer-Roseneder I, Feldmeier S, Kristöfel C, Ehrig R, Schwabl M, Strasser C, Wörgetter M. Torrefied pellets – influence of torrefaction on pellet characteristics and combustion behavior, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details


Kontaktieren Sie uns

Sie erreichen unser Office unter der Adresse office@bioenergy2020.eu

Nutzen Sie auch die Möglichkeit, direkt von dieser Webseite eine Nachricht an unsere Mitarbeiter_innen zu schicken. Schnell und unkompliziert.

Zur Team-Seite