Combustion of Difficult Biomass Fuels: from Particle Ignition to Large-Scale Studies
Wed / 19.04. @ 09:00
The intense use of wood derived fuels in (co-)firing processes is putting an enormous pressure on the forest. In order to alleviate this pressure, while increasing the use of biomass in (co-)firing processes and thereby reduce CO2 emissions, it is necessary to increase the use of alternative biomass fuels, in particular herbaceous materials and agricultural residues. (Co-)firing using such residues can cause a number of problems because of the presence of alkali metals and chlorine and other ash related impacts as well as corrosion on the metallic surfaces and particulate matter emissions. This may limit the variety of biomass fuels that can actually be used in (co-)firing processes. This talk will address the combustion of alternative biomass fuels and will include particle ignition, drop tube and small- and large-scale studies.
Prof. Mário Costa
Instituto Superior Técnico
Mário Costa is a Full Professor in the area of Environment and Energy at the Mechanical Engineering Department of Instituto Superior Técnico (IST). He graduated in Chemical Engineering at University of Coimbra in 1984, obtained his PhD in Mechanical Engineering at Imperial College London in 1992 and his Habilitation in Mechanical Engineering at Technical University of Lisbon in 2009. Currently, he teaches the courses of Thermodynamics, Combustion, Renewables Energies and Integrated Energy Systems. He has supervised more than 100 MSc and Phd students. He has participated in more than 50 national and international projects in the area of Energy and Environment and has (co-)authored 1 book, more than 100 papers in international peer-reviewed journals and more than 150 papers in international conferences. He was the recipient of the Caleb Brett Award of the Institute of Energy in 1991, of the Sugden Award of the British Section of the Combustion Institute in 1991, of the Prémio Científico UTL/Santander Totta in 2010 and of a Menção Honrosa Universidade de Lisboa/Santander in 2016.
Multidimensional Simulation of IC-Engine Combustion and Pollutant Formation – Current Status and Future Challenges
Wed / 19.04. @ 14:00
Over the last three decades modeling of the physical and chemical processes governing combustion and pollutant formation in internal combustion engines has continuously been refined and improved. Considerable progress has been made in modeling the combustion process itself, both in terms of reflecting the turbulence / chemistry interaction and in modeling the unburned / burned interface of the propagating flame during premixed combustion. Moreover, the models for simulating the formation of undesired gaseous and particulate emissions under both compression-ignition and spark-ignition combustion conditions have also reached a remarkable level of accuracy and maturity.
Nevertheless, current and future IC-engine development trends pose a number of new challenges onto the combustion modeling and simulation community. The accurate simulation of future alternative combustion concepts requires e.g. further refined models for accurate treatment of the local transition from auto-ignition to premixed and diffusion combustion. The increasing usage of bio-fuels, synthetic fuels and other types of alternative fuels leads to a strong demand for reliable and validated detailed chemical kinetic reaction schemes, capable of reflecting the auto-ignition and combustion characteristics of these fuels for the relevant wide range of in-cylinder conditions. The demand for extended long term stability of the combustion and pollutant formation characteristics of future IC-engines additionally results in an increased need for simulation capabilities enabling the study of transient phenomena, such as cycle-to-cycle combustion variations or the onset of knocking combustion.
An overview of the currently most widely adopted approaches for modeling the various physical and chemical processes governing combustion and pollutant formation in IC-engines will be provided together with an outlook on current and future modeling trends. Based on selected application examples for different engine types and combustion systems the present status achieved in modeling IC-engine combustion and pollutant formation in realistic configurations as well as the current and upcoming future challenges will be addressed.
Dr. Reinhard Tatschl
AVL List GmbH
Dr. Tatschl received his PhD from Graz University of Technology for his work in the field of multidimensional simulation of spark ignition and early flame kernel growth in fuel/air mixtures adopting a generic hydrocarbon reaction scheme. His research interest at AVL is on modeling turbulent combustion and the related pollutant formation processes for simulation of all kinds of internal combustion engines and general technical combustion devices. This also comprises modeling activities related to multiphase flow processes in fuel injectors, liquid fuel spray propagation accounting for primary and secondary atomization details, as well as activities in the area of pollutant after-treatment modeling. In recent years his research interest has expanded also into the area of modeling electrochemical storage and conversion processes in batteries and fuel cells, respectively. As a result of these research activities, he has got more than 100 publications in scientific journals, books and international conference proceedings. During his work for AVL Dr. Tatschl has been active in different positions in the area of CFD development, currently he holds the position Research and Technology Manager at the business unit Advanced Simulation Technologies.
Chemical Kinetic Optimization and Uncertainty Quantification
Thu / 20.04. @ 09:00
Shock tube and flow reactor measurements are frequently used for the determination of the Arrhenius parameters of selected elementary reactions.
The experiments are carried out at conditions where the measured data mainly depend on the rate parameters of a single reaction, the rate coefficient is fitted to the data at each temperature, and the Arrhenius parameters are determined from the rate coefficients obtained at several temperatures. If other reactions are also non-negligible, the uncertainties of their rate parameters are considered as perturbation factors.
This way only a rough estimation of the uncertainty of rate parameters can be obtained. We suggest a different approach, where all measured data are used together, the rate parameters of all significant reactions are fitted simultaneously, and all experimental and theoretical information found in the literature for these reactions is also used. This way better established rate parameters can be obtained, accompanied with a more accurate estimation of the uncertainty of the parameters.
The same methodology can be used for the development of improved detailed reaction mechanisms. For the combustion of a selected fuel, all indirect experimental data (e.g. flame velocities and ignition delay times), and direct experimental and theoretical determinations of rate coefficients of the significant reactions are collected. All these data are used simultaneously during the kinetic optimization, leading to a full utilization of all available information.
The result is an accurate detailed reaction mechanism and well characterized joint uncertainty of all determined rate parameters. This approach has been used for making more accurate reaction mechanisms for the description of the combustion of hydrogen, syngas, methanol, ethanol and methane
Prof. Tamas Turanyi
Eötvös Loránd University
Tamás Turányi received an MSc in Chemistry in 1983 at the Eötvös Loránd University (ELTE), Budapest, Hungary. He also received an MSc in Applied Mathematics in 1988 at the same university. He started to work in the field of experimental gas kinetics at the Central Research Institute for Chemistry of the Hungarian Academy of Sciences in Budapest. He received his PhD degree in 1988 at the ELTE and was a postdoc in the group of Prof. Mike Pilling at the School of Chemistry, University of Leeds, UK, in years 1990-92 and 1994-95. He is working at the Institute of Chemistry of ELTE since 1996. He became a Professor of Chemistry in 2007. His main research interest is the simulation of chemical kinetic models based on detailed reaction mechanisms; development, analysis, uncertainty quantification and reduction of reaction mechanisms. The results are used in combustion, atmospheric chemistry and biochemical simulations. Prof. Turányi has published 130 scientific papers and received more than 3000 citations.
Lagrangian Modelling of Droplet Collisions in Spraying Systems
Thu / 20.04. @ 14:00
Fuel injection systems produce very fine sprays with high local droplet number concentration in the vicinity of the atomizer (i.e. downstream of the break-up region).
Thereby, very high probabilities of droplet collisions are produced which considerably alter the spray droplet size distribution; coalescence increases droplet size and separation is mostly associated with the production of a number of very fine satellites.
Moreover, in spray combustion systems multiple injector holes or multiple spray nozzles are being used which increase droplet collision probability. Therefore, in spray simulations, mostly based on Euler/Lagrange approaches, accurate droplet collision models are required as a basis for predicting spray evaporation and combustion.
For detecting droplet collisions the fully stochastic collision model is used by additionally including the effect of impact efficiency for inertial droplets hitting a larger droplet. Then the outcome of droplet collisions has to be decided based on the well-known collision map; i.e. impact parameter plotted versus Weber-number.
For this, appropriate boundary lines between collision scenarios, namely lower boundary of bouncing, boundary between coalescence and stretching separation as well as between reflexive separation and coalescence are required. Generally, these boundary lines are based on measurements conducted for water.
Hence their application for Gasoline or Diesel sprays is not justified. Therefore, an approach has been developed for generalizing the collision maps by using the triple-point location (i.e. coincidence of bouncing, stretching separation and coalescence) and the critical Weber-number (onset of reflexive separation).
It is known that their location is changing with droplet size ratio and liquid properties. The boundary line models are adapted to go through these characteristic points. This improved hybrid model has been implemented into an Euler/Lagrange code and validated against results obtained for different spraying systems,
also including two interacting sprays where high droplet collision rates are found. In these experiments also the properties of the atomized liquid was changed.
Prof. Martin Sommerfeld
Martin Sommerfeld (Prof. Dr.-Ing) studied aeronautical engineering at the Technical University Aachen and received his Diploma in 1981. He completed his Doctoral degree (shock wave propagation through gas-particle mixtures) at the same University in 1984. Then he spent one year at Kyoto University Japan on a research fellowship. In 1986 he moved to the Institute of Fluid Mechanics (Prof. Durst, University Erlangen), headed the Two-Phase Flow research group and completed a Habilitation “Modelling and Calculation of Particle-Laden Flows using the Euler/Lagrange Approach”. In October 1994 he was appointed Professor of Mechanical Process Engineering (University Halle, Germany). In 1997 he received the DECHEMA Award for contributions to multiphase flow measurements, modelling and numerical prediction.
Martin Sommerfeld organised a continuing series of workshops on two-phase flow predictions, ASME symposia, the Int. Conf. on Multiphase Flow (ICMF 2007) and several other international conferences. He is chair of the ERCOFTAC special interest group “dispersed two-phase flows” and the ProcessNet special topic group “computational fluid dynamics”. He has written 170 reviewed journal papers, 190 conference papers and several books and monographs, among that the book “Multiphase Flows with Droplets and Particles”. (2nd Edition, Crowe et al. 2012) and the ERCOFTAC Best Practice Guidelines for Computational Fluid Dynamics of Dispersed Multiphase Flows.
His research activities are mainly concerned with fundamentals of dispersed multi-phase flows with the aim of developing physical models for describing relevant transport phenomena. For the analysis of multi-phase flow phenomena detailed experiments using modern optical instrumentation as well as direct numerical simulations by the Lattice-Bolzmann-Method are performed. The developed models are used in the frame of the Euler/Lagrange computational approach for allowing the prediction of industrial processes involving dispersed multi-phase flows.
The Importance of Waste Incineration for Urban Mining
Fri / 21.04. @ 09:00
In these recent times there are many challenges for combustion, however combustion technology is a very versatile tool with many different aspects. Among the wide range of potential fuels, waste is one of the most challenging ones.
The waste of a city varies in a wide range and is strictly time dependent. If it cannot be avoided or re-used or recycled it should undergo incineration at optimized conditions producing heat and power. However it is not only the combustion process itself that has to be optimized it is also fuel preparation,
fuel conversion, flue gas cleaning and bottom and fly ash handling. And there is not only one incineration technology, i.e. grate furnaces, fluidized beds or rotary kilns. However the waste of a city (municipal solid waste, commercial waste, sewage sludge and hazardous waste)
may also contain valuable materials which may be of importance for urban mining. This work discusses the importance of waste incineration and its potential for urban mining with the example of the Viennese waste incineration cluster which consists of 13 combustion lines utilizing about one million tons of waste each year.
Prof. Franz Winter
Prof. Franz Winter is the head of the research division Chemical Process Engineering & Energy Technology at the Institute of Chemical Engineering at Vienna University of Technology. The group currently consists of about 25 full-time PhD researchers, technicians and diploma students funded by research projects from EU, industry and Austrian funds in the field of energy conversion, environmental technology and chemical engineering.
His research fields are modeling and experimental work in:
- Energy conversion, Waste, Biomass, Fluidized Bed Combustion
- Combustion chemistry, Combustion in
- Environmental technology, Recycling
- NOx/N2O, CO, CO2, SO2, HCl, particulate emissions, ash
He gives lectures in: Chemical Engineering, Combustion Chemistry, Energy Technology, Industrial Synthesis, and is advisor of numerous master-theses and Ph.D.-theses.
He published more than 80 peer-reviewed journal publications and more than 150 reviewed international conference papers. He is co-editor of the Handbook of Combustion and author of the book Combustion. He was chairman of the 19th Int. Conf. on Fluidized Bed Combustion 2006, chairman of the 4th European Combustion Meeting 2009, chairman of the Int. Conf. on Fuel Quality 2012 and was chairman and vice-chairman of the International Energy Agency (IEA) – Fluidized Bed Conversion (FBC) group.