Sortierung Titel Year

Publikationen


Peer Reviewed Scientific Journals | 2020

Investigation of solid oxide fuel cell operation with synthetic biomass gasification product gases as a basis for enhancing its performance

Pongratz G, Subotić V, Schroettner H, Stoeckl B, Hochenauer C, Anca-Couce A, Scharler R. Investigation of solid oxide fuel cell operation with synthetic biomass gasification product gases as a basis for enhancing its performance. Biomass Conversion and Biorefinery.2020.

External Link

Details

Solid oxide fuel cells represent a promising technology to increase the electrical efficiency of biomass-based combined-heat-power systems in comparison to state-of-the-art gas engines, additionally providing high temperature heat. To identify favorable fuel gas compositions for an efficient coupling with gasifiers at low degradation risk is of major importance to ensure stability, reliability, and durability of the systems used, thus increasing attractiveness of electricity production from biomass. Therefore, this study presents a comprehensive analysis on the influence of main gas components from biomass gasification on the performance and efficiency of a cell relevant for real application. An industrial-size electrolyte supported single cell with nickel/gadolinium-doped ceria anode was selected showing high potential for gasifier-solid oxide fuel cell systems. Beneficial gas component ratios enhancing the power output and electric efficiency are proposed based on the experimental study performed. Furthermore, the degradation stability of a SOFC fueled with a synthetic product gas representing steam gasification of woody biomass was investigated. After 500 h of operation under load at a steam-to-carbon ratio of 2.25 in the fuel gas, no performance or anode degradation could be detected.


Conference contributions | 2020

Lessons Learned from Alternative Fuels Experience

Sonnleitner A. Lessons Learned from Alternative Fuels Experience. 6th Central European Biomass Conference, 22-24 January 2020, Graz

Download PDF

Details


Conference contributions | 2020

Microgrid Lab 100 % - R&D project for decentralized energy supply with biomass and other Distributed energy Resources

Aigenbauer S. Microgrid Lab 100 % - R&D project for decentralized energy supply with biomass and other Distributed energy Resources. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Conference contributions | 2020

Microgrid Lab 100% Testbed for the development of control algorithms for microgrids

Aigenbauer S, Microgrid Lab 100% Testbed for the development of control algorithms for microgrids. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Peer Reviewed Scientific Journals | 2020

Model-based control of hydraulic heat distribution systems — Theory and application

Unterberger V, Muschick D, Loidl A, Poms U, Gölles M, Horn M. Model-based control of hydraulic heat distribution systems — Theory and application. Control Engineering Practice. 2020;2020(101).104464. https://doi.org/10.1016/j.conengprac.2020.104464

External Link

Details

With the share of renewable energy sources increasing in heating and hot water applications, the role of hydraulic heat distribution systems is becoming more and more important. This is due to the fact that in order to compensate for the often fluctuating behaviour of the renewables a flexible heat transfer must be ensured by these distribution systems while also taking the optimal operating conditions (mass flow, temperature) of the individual components into consideration. This demanding task can be accomplished by independently controlling the two physical quantities mass flow and temperature. However, since there exists an intrinsic nonlinear coupling between these quantities this challenge cannot be handled sufficiently by decoupled linear PI controllers which are currently state-of-the-art in the heating sector. For this reason this paper presents a model-based control strategy which allows a decoupled control of mass flow and temperature. The strategy is based on a systematic design approach from models described in this contribution, which are validated by commercially available components from which most of them can be parametrized by the data sheet. The control strategy is designed for a typical hydraulic configuration used in heating systems, which will allow the accurate tracking of the desired trajectories for mass flows, temperatures and consequently heat flows. The controllers are validated experimentally and compared to well-tuned state-of-the-art (PI) controllers in order to illustrate their superiority and prove their decoupling of the control of mass flow and temperature in real world applications.


Conference contributions | 2020

Model-based estimation of the flue gas mass flow in biomass furnaces

Niederwieser H. Model-based estimation of the flue gas mass flow in biomass furnaces. 6th Central European Biomass Conference. 22-24 January 2020, Graz.

Download PDF

Details


Other Presentations | 2020

Modern control strategies for biomass combustion systems in residential heating systems

Gölles M, Zemann C. Modern control strategies for biomass combustion systems in residential heating systems. At 6th Central European Biomass Conference IEA-Workshop: TASK 32. Oral Presenation. 23.01.2020.

Download PDF

Details


Conference contributions | 2020

Modern control strategies for biomass combustion systems in residential heating systems

Gölles M, Zemann C. Modern control strategies for biomass combustion systems in residential heating systems. 6th Central European Biomass Conference, 2020, Graz.

Download PDF

Details


Conference contributions | 2020

Modification of ash properties in fixed bed combustion systems

Sommersacher P, Retschitzegger S. Modification of ash properties in fixed bed combustion systems. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Conference contributions | 2020

NOx Modelling and Emission Reduction

Eßl M, NOx Modelling and Emission Reduction. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Scientific Journals | 2020

Off-gassing reduction of stored wood pellets by adding acetylsalicylic acid

Sedlmayer I, Bauer-Emhofer W, Haslinger W, Hofbauer H, Schmidl C, Wopienka E. Off-gassing reduction of stored wood pellets by adding acetylsalicylic acid. Fuel Processing Technology 2020.198:106218.

External Link

Details

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.


Conference contributions | 2020

Optimization based planning of energy systems

Zellinger M, Optimization based planning of energy systems. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Peer Reviewed Scientific Journals | 2020

Prediction of slag related problems during fixed bed combustion of biomass by application of a multivariate statistical approach on fuel properties and burner technology

Rebbling A, Näzelius IL, Schwabl M, Feldmeier S, Schön C, Dahl J, Haslinger W, Boström D, Öhman M, Boman C. Prediction of slag related problems during fixed bed combustion of biomass by application of a multivariate statistical approach on fuel properties and burner technology. Biomass and Bioenergy 2020.137:105557.

External Link

Details

Slag is related to the melting properties of ash and is affected by both the chemical composition of the fuel ash and the combustion parameters. Chemical analysis of slag from fixed bed combustion of phosphorus-poor biomass show that the main constituents are Si, Ca, K, O (and some Mg, Al, and Na), which indicates that the slag consists of different silicates. Earlier research also points out viscosity and fraction of the ash that melts, as crucial parameters for slag formation. To the authors’ knowledge, very few of the papers published to this day discuss slagging problems of different pelletized fuels combusted in multiple combustion appliances. Furthermore, no comprehensive classification of both burner technology and fuel ash parameters has been presented in the literature so far. The objective of the present paper was therefore to give a first description of a qualitative model where ash content, concentrations of main ash forming elements in the fuel and type of combustion appliance are related to slagging behaviour and potential operational problems of a biomass fuel in different small- and medium scale fixed bed appliances.

Based on the results from the combustion of a wide range of pelletized biomass fuels in nine different burners, a model is presented for amount of slag formed and expected severity of operational problems. The model was validated by data collected from extensive combustion experiments and it can be concluded that the model predicts qualitative results.


Conference contributions | 2020

Primary- and Secondary Measures for Manually Fired Stoves - An Overview

Reichert G. Primary- and Secondary Measures for Manually Fired Stoves - An Overview. 6th Central European Biomass Conference, 2020, Graz.

Download PDF

Details


Conference contributions | 2020

Product flexibility from biomass steam gasification applying gas upgrading and synthesis processes

Binder M, Product flexibility from biomass steam gasification applying gas upgrading and synthesis processes. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Conference contributions | 2020

Reliability of TGA data for characterization of alternative biomass feedstocks

Retschitzegger S, Kienzl N, Anca-Couce A, Tsekos C, Banks S, Kraia T, Zimbardi F, Funke A, Marques P. Reliability of TGA data for characterization of alternative biomass feedstocks. 6th Central European Biomass Conference, 2020, Graz.

Download PDF

Details


Peer Reviewed Scientific Journals | 2020

Scale-up methodology for automatic biomass furnaces

Barroso G, Nussbaumer T, Ulrich M, Reiterer T, Feldmeier S. Scale-up methodology for automatic biomass furnaces. Journal of the Energy Institute 2020.93:591-604.

External Link

Details

This work presents a methodology to perform the scale-up of a solid fuel furnace to a higher heat output with maintaining or improving the burn-out quality. As basis to derive the scale-up concept, an example of a 35 kW screw burner for biomass fuels is investigated. Based on the Pi-theorem, the relevant dimensionless parameters are derived and similarity rules for the scale-up are proposed as follows: As initial conditions, the height to diameter ratio of the combustion chamber, the mean Reynolds number in the combustion chamber and the mean square velocity through the combustion chamber shall be kept constant or in the case of the Reynolds number may also increase. Additionally the effective momentum flux ratio between the secondary air injected in the combustion chamber and the gases from the pyrolysis and gasification section also shall be kept constant to maintain the mixing conditions between combustible gases and secondary air. Finally the thermal surface load on the screw also shall be kept constant. The influence of different scale-up approaches on thermal surface load, gas velocity, pressure losses, Reynolds number and height-to-diameter ratio are compared and discussed and a scaling approach to increase the heat output from 35 kW to 150 kW is described. For a theoretical validation of the scale-up, CFD simulations are performed to investigate the predicted pollutant emissions and the pressure loss for the scaled 150 kW furnace.


Conference contributions | 2020

Techno-economic modelling of bioeconomy value chains

Fuhrmann Marilene

Fuhrmann M. Techno-economic modelling of bioeconomy value chains. 6th Central European Biomass Conference. 2020. Graz.

Download PDF

Details


Peer Reviewed Scientific Journals | 2020

The effect of the reaction equilibrium on the kinetics of gas-solid reactions — A non-parametric modeling study.

Birkelbach F, Deutsch M, Werner A. The effect of the reaction equilibrium on the kinetics of gas-solid reactions — A non-parametric modeling study. Renewable Energy 2020.152:300-307.

External Link

Details

The viability of thermochemical energy storage for a given application is often determined by the reaction kinetics under process conditions. For high exergetic efficiency the process needs to operate in close proximity to the reaction equilibrium. Thus, accurate kinetic models that include the effect of the reaction equilibrium are required.

In the present work, different parametrization methods for the equilibrium term in the General Kinetic Equation are evaluated by modeling the kinetics of two reaction systems relevant for thermochemical energy storage (CaC2O4 and CuO) from experimental data. A non-parametric modeling method based on tensor decompositions is used that allows for a purely data driven assessment of different parametrization methods.

Our analysis shows that including a suitable equilibrium term is crucial. Omitting the equilibrium term when modeling formation reactions can lead to seemingly negative activation energies. Our tests also show that for formation reactions, the reaction rate decreases much faster towards the equilibrium than theory predicts. We present an empirical modeling approach that can predict the reaction rate of gas-solid reactions, regardless of the shortcomings of theory. In this way, non-parametric modeling offers a powerful tool for applied research and may contribute to the advancement of the thermochemical energy storage technology.


Peer Reviewed Scientific Journals | 2020

Thermochemical equilibrium study of ash transformation during combustion and gasification of sewage sludge mixtures with agricultural residues with focus on the phosphorus speciation

Hannl TK, Sefidari H, Kub M, Skoglund N, Öhmann M. Thermochemical equilibrium study of ash transformation during combustion and gasification of sewage sludge mixtures with agricultural residues with focus on the phosphorus speciation. Biomass Conversion and Biorefinery.2020

External Link

Details

The necessity of recycling anthropogenically used phosphorus to prevent aquatic eutrophication and decrease the economic dependency on mined phosphate ores encouraged recent research to identify potential alternative resource pools. One of these resource pools is the ash derived from the thermochemical conversion of sewage sludge. This ash is rich in phosphorus, although most of it is chemically associated in a way where it is not plant available. The aim of this work was to identify the P recovery potential of ashes from sewage sludge co-conversion processes with two types of agricultural residues, namely wheat straw (rich in K and Si) and sunflower husks (rich in K), employing thermodynamic equilibrium calculations. The results indicate that both the melting behavior and the formation of plant available phosphates can be enhanced by using these fuel blends in comparison with pure sewage sludge. This enhanced bioavailability of phosphates was mostly due to the predicted formation of K-bearing phosphates in the mixtures instead of Ca/Fe/Al phosphates in the pure sewage sludge ash. According to the calculations, gasification conditions could increase the degree of slag formation and enhance the volatilization of K in comparison with combustion conditions. Furthermore, the possibility of precipitating phosphates from ash melts could be shown. It is emphasized that the results of this theoretical study represent an idealized system since in practice, non-equilibrium influences such as kinetic limitations and formation of amorphous structures may be significant. However, applicability of thermodynamic calculations in the prediction of molten and solid phases may still guide experimental research to investigate the actual phosphate formation in the future.


Peer Reviewed Scientific Journals | 2020

Transient CFD simulation of wood log combustion in stoves

Scharler R, Gruber T, Ehrenhöfer A, Kelz J, Mehrabian Bardar R, Bauer T, Hochenauer C, Anca-Couce A. Transient CFD simulation of wood log combustion in stoves. Renewable Energy 2020.145:651-662

External Link

Details

Wood log stoves are a common residential heating technology that produce comparably high pollutant emissions. Within this work, a detailed CFD model for transient wood log combustion in stoves was developed, as a basis for its optimization. A single particle conversion model previously developed by the authors for the combustion of thermally thick biomass particles, i.e. wood logs, was linked with CFD models for flow and turbulence, heat transfer and gas combustion. The sub-models were selected based on a sensitivity analysis and combined into an overall stove model, which was then validated by simulations of experiments with a typical wood log stove, including emission measurements. The comparison with experimental results shows a good accuracy regarding flue gas temperature as well as CO2 and O2 flue gas concentrations. Moreover, the characteristic behavior of CO emissions could be described, with higher emissions during the ignition and burnout phases. A reasonable accuracy is obtained for CO emissions except for the ignition phase, which can be attributed to model simplifications and the stochastic nature of stove operation. Concluding, the CFD model allows a transient simulation of a stove batch for the first time and hence, is a valuable tool for process optimization.


Conference contributions | 2020

Valorisation of industrial by-products from the pulp&paper and rendering industry

Ortner M, Valorisation of industrial by-products from the pulp&paper and rendering industry. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details


Conference contributions | 2020

Virtual biomass combustion plant

Schulze K, Virtual biomass combustion plant. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

Download PDF

Details