An Investigation of Combustion Properties of Butanol and its Potential for Power Generation

2017 ◽  
Author(s):  
Torsten Methling ◽  
Sandra Richter ◽  
Trupti Kathrotia ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Transformation Method ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times ◽  
Reaction Models

Over the last years, global concerns about energy security and climate change have resulted in many efforts focusing on the potential utilization of non-petroleum-based, i.e. bio-derived, fuels. In this context, n-butanol has recently received high attention because it can be produced sustainably. A comprehensive knowledge about its combustion properties is inevitable to ensure an efficient and smart use of n-butanol if selected as a future energy carrier. In the present work, two major combustion characteristics, here laminar flame speeds applying the cone-angle method and ignition delay times applying the shock tube technique, have been studied, experimentally and by modeling exploiting detailed chemical kinetic reaction models, at ambient and elevated pressures. The in-house reaction model was constructed applying the RMG-method. A linear transformation method recently developed, linTM, was exploited to generate a reduced reaction model needed for an efficient, comprehensive parametric study of the combustion behavior of n-butanol/hydrocarbon mixtures. All experimental data were found to agree with the model predictions of the in-house reaction model, for all temperatures, pressures, and fuel-air ratios. On the other hand, calculations using reaction models from the open literature mostly overpredict the measured ignition delay times by about a factor of two. The results are compared to those of ethanol, with ignition delay times very similar and laminar flame speeds of n-butanol slightly lower, at atmospheric pressure.

An Investigation of Combustion Properties of Butanol and Its Potential for Power Generation

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Torsten Methling ◽  
Sandra Richter ◽  
Trupti Kathrotia ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Transformation Method ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times ◽  
Reaction Models

Over the last years, global concerns about energy security and climate change have resulted in many efforts focusing on the potential utilization of nonpetroleum-based, i.e., bioderived, fuels. In this context, n-butanol has recently received high attention because it can be produced sustainably. A comprehensive knowledge about its combustion properties is inevitable to ensure an efficient and smart use of n-butanol if selected as a future energy carrier. In the present work, two major combustion characteristics, here laminar flame speeds applying the cone-angle method and ignition delay times applying the shock tube technique, have been studied, experimentally, and by modeling exploiting detailed chemical kinetic reaction models, at ambient and elevated pressures. The in-house reaction model was constructed applying the reaction model generation (RMG)-method. A linear transformation method recently developed, linTM, was exploited to generate a reduced reaction model needed for an efficient, comprehensive parametric study of the combustion behavior of n-butanol-hydrocarbon mixtures. All experimental data were found to agree with the model predictions of the in-house reaction model, for all temperatures, pressures, and fuel-air ratios. On the other hand, calculations using reaction models from the open literature mostly overpredict the measured ignition delay times by about a factor of two. The results are compared to those of ethanol, with ignition delay times very similar and laminar flame speeds of n-butanol slightly lower, at atmospheric pressure.

Alternative Fuels Based on Biomass: An Investigation of Combustion Properties of Product Gases

2012 ◽  
Author(s):  
Jürgen Herzler ◽  
Julia Herbst ◽  
Thomas Kick ◽  
Clemens Naumann ◽  
Marina Braun-Unkhoff ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Alternative Fuels ◽  
Electrical Power ◽  
Cone Angle ◽  
Chemical Kinetic ◽  
Gas Mixtures ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times ◽  
Reaction Models

Fuels from low quality feedstock such as biomass and biomass residues are currently discussed with respect to their potential to contribute to a more sustainable electrical power supply. In the present work, we report on the study of generic representative gas mixtures stemming from the gasification of different feedstock, from wood and algae. Two major combustion properties — burning velocities and ignition delay times — were measured for different parameters: (i) for two pressures −1 bar and 3 bar – at a constant preheat temperature T0 = 373 K, to determine burning velocities by applying the cone angle method; and (ii) for elevated pressures — up to 16 bar — in the temperature range between about 1000 and 2000 K, at fuel-equivalence ratios φ of 0.5 and 1.0, to obtain ignition delay times by applying the shock tube method. Additional studies performed in our group on gas mixtures of natural gas, methane, and hydrogen were also taken into account -as major components of biogenic gas mixtures. It was found that the reaction behavior of the wood gasification product (N2, CO, H2, CO2, CH4) is mainly determined by its H2 content, besides CH4; methane determines the kinetic behavior of the algae fermentation product (CH4, CO2, N2) due to its relatively high amount. Detailed chemical kinetic reaction models were used to predict the measured data. The trends and main features were captured by predictions applying different reaction models. The agreement of the experiments and the predictions is dependent on the pressure range.

Alternative Fuels Based on Biomass: An Investigation of Combustion Properties of Product Gases

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jürgen Herzler ◽  
Julia Herbst ◽  
Thomas Kick ◽  
Clemens Naumann ◽  
Marina Braun-Unkhoff ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Alternative Fuels ◽  
Electrical Power ◽  
Cone Angle ◽  
Chemical Kinetic ◽  
Gas Mixtures ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times ◽  
Reaction Models

Fuels from low quality feedstock such as biomass and biomass residues are currently discussed with respect to their potential to contribute to a more sustainable electrical power supply. In the present work, we report on the study of generic representative gas mixtures stemming from the gasification of different feedstock, from wood and algae. Two major combustion properties—burning velocities and ignition delay times—were measured for different parameters: (i) for two pressures—1 bar and 3 bar—at a constant preheat temperature T0 = 373 K, to determine burning velocities by applying the cone angle method; and (ii) for elevated pressures—up to 16 bar—in the temperature range between about 1000 and 2000 K, at fuel-equivalence ratios φ of 0.5 and 1.0, to obtain ignition delay times by applying the shock tube method. Additional studies performed in our group on gas mixtures of natural gas, methane, and hydrogen were also taken into account as major components of biogenic gas mixtures. It was found that the reaction behavior of the wood gasification product (N2, CO, H2, CO2, CH4) is mainly determined by its H2 content, besides CH4; methane determines the kinetic behavior of the algae fermentation product (CH4, CO2, N2) due to its relatively high amount. Detailed chemical kinetic reaction models were used to predict the measured data. The trends and main features were captured by predictions applying different reaction models. The agreement of the experiments and the predictions is dependent on the pressure range.

A Study on Fundamental Combustion Properties of Oxymethylene Ether-2

2021 ◽  
Author(s):  
John N. Ngugi ◽  
Sandra Richter ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
Markus Köhler ◽  
...  
Keyword(s):  
Experimental Data ◽  
Reaction Mechanisms ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Sensitivity Analyses ◽  
Chain Reactions ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

Abstract Oxymethylene ethers (OMEn, n = 1–5) are a promising class of synthetic fuels that have the potential to be used as additives or substitutes to diesel in compression ignition engines. A comprehensive understanding of their combustion properties is required for their safe and efficient utilization. In this study, the results of a combined experimental and modeling work on oxidation of OME2 are reported: (i) Ignition delay time measurements of stoichiometric OME2 / synthetic air mixtures diluted 1:5 with nitrogen using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) laminar flame speeds of OME2 / air mixtures using the cone angle method at ambient and elevated pressures of 3 and 6 bar. The experimental data sets obtained have been used for validation of a detailed reaction mechanisms of OME2. The results of ignition delay times showed that OME2 exhibits a two-stage ignition in the lower temperature region. There is a good match of the measured data compared to the predicted ones using three reaction mechanisms from the literature. The mechanism from Cai et al. (2020) best predicted the temperature and pressure dependence of ignition delay times. For laminar flame speeds, the experimental data were well matched by the mechanism from Ren et al. (2019) at p = 1, 3, and 6 bar and for all equivalence ratios considered. From sensitivity analyses calculations, it was observed that chain reactions involving small radicals, i.e., H, O, OH, HO2, and CH3 control the oxidation of OME2. The comparison of the results of this work and our previous work (Ngugi et al. (2021)) on OME1 show that these two fuels have similar oxidation pathways. The results obtained in this work will contribute to a better understanding of the combustion of oxymethylene ethers, and thus, to the design and optimization of burners and engines as well.

A Study On Fundamental Combustion Properties of Oxymethylene Ether-2

2021 ◽  
Author(s):  
John Mburu Ngugi ◽  
Sandra Richter ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
Markus Köhler ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Sensitivity Analyses ◽  
Chain Reactions ◽  
Design And Optimization ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

Abstract Oxymethylene ethers (OMEn, n=1-5) are a promising class of synthetic fuels that have the potential to be used as diesel additives or substitutes. A comprehensive understanding of their combustion properties is required for their safe and efficient utilization. In this study, a combined experimental and modeling work on oxidation of OME2 is reported: (i) Ignition delay time measurements of stoichiometric OME2 / synthetic air mixtures diluted 1:5 with nitrogen using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) laminar flame speeds of OME2 / air mixtures using the cone angle method at pressures of 1, 3 and 6 bar. The experimental data obtained have been used for validation of three detailed reaction mechanisms of OME2. The results of ignition delay times showed that OME2 exhibits a two-stage ignition in the lower temperature region. The mechanism from Cai et al. (2020) best predicted the temperature and pressure dependence of ignition delay times. For laminar flame speeds, the experimental data were well matched by the mechanism from Ren et al. (2019) for all the conditions of pressures and equivalence ratios considered. From sensitivity analyses, it was observed that chain reactions involving small radicals, i.e., H, O, OH, HO2, and CH3 control the oxidation of OME2. The results obtained in this work will contribute to a better understanding of the combustion of oxymethylene ethers, and thus, to the design and optimization of burners and engines as well.

scholarly journals Alternative Fuels Based on Biomass: An Experimental and Modeling Study of Ethanol Cofiring to Natural Gas

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Marina Braun-Unkhoff ◽  
Jens Dembowski ◽  
Jürgen Herzler ◽  
Jürgen Karle ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Kinetic Modeling ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Parameter Range ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

In response to the limited resources of fossil fuels as well as to their combustion contributing to global warming through CO2 emissions, it is currently discussed to which extent future energy demands can be satisfied by using biomass and biogenic by-products, e.g., by cofiring. However, new concepts and new unconventional fuels for electric power generation require a re-investigation of at least the gas turbine burner if not the gas turbine itself to ensure a safe operation and a maximum range in tolerating fuel variations and combustion conditions. Within this context, alcohols, in particular, ethanol, are of high interest as alternative fuel. Presently, the use of ethanol for power generation—in decentralized (microgas turbines) or centralized gas turbine units, neat, or cofired with gaseous fuels like natural gas (NG) and biogas—is discussed. Chemical kinetic modeling has become an important tool for interpreting and understanding the combustion phenomena observed, for example, focusing on heat release (burning velocities) and reactivity (ignition delay times). Furthermore, a chemical kinetic reaction model validated by relevant experiments performed within a large parameter range allows a more sophisticated computer assisted design of burners as well as of combustion chambers, when used within computational fluid dynamics (CFD) codes. Therefore, a detailed experimental and modeling study of ethanol cofiring to NG will be presented focusing on two major combustion properties within a relevant parameter range: (i) ignition delay times measured in a shock tube device, at ambient (p = 1 bar) and elevated (p = 4 bar) pressures, for lean (φ = 0.5) and stoichiometric fuel–air mixtures, and (ii) laminar flame speed data at several preheat temperatures, also for ambient and elevated pressure, gathered from literature. Chemical kinetic modeling will be used for an in-depth characterization of ignition delays and flame speeds at technical relevant conditions. An extensive database will be presented identifying the characteristic differences of the combustion properties of NG, ethanol, and ethanol cofired to NG.

HEEDS Optimized HyChem Mechanisms

2017 ◽  
Author(s):  
Graham Goldin ◽  
Zhuyin Ren ◽  
Yang Gao ◽  
Tianfeng Lu ◽  
Hai Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Chemical Kinetic ◽  
Flame Speed ◽  
Cfd Simulations ◽  
Transportation Fuels ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Fuel Pyrolysis

Transportation fuels consist of a large number of hydrocarbon components and combust through an even larger number of intermediates. Detailed chemical kinetic models of these fuels typically consist of hundreds of species, and are computationally expensive to include directly in 3D CFD simulations. HyChem (Hybrid Chemistry) is a recently proposed modeling approach for high-temperature fuel oxidation based on the assumptions that fuel pyrolysis is fast compared to the subsequent oxidation of the small fragments, and that, although their proportions may differ, all fuels pyrolyse to similar sets of these fragment species. Fuel pyrolysis is hence modeled with a small set of lumped reactions, and oxidation is described by a compact C0-4 foundation chemistry core. The stoichiometric coefficients of the global pyrolysis reactions are determined to match experimental or detailed mechanism computational data, such as shock-tube pyrolysis products, ignition delays and laminar flame speeds. The model is then validated against key combustion properties, including ignition delays, laminar flame speeds and extinction strain rates. The resulting HyChem model is relatively small and computationally tractable for 3D CFD simulations in complex geometries. This paper applies the HEEDS optimization tool to find optimal pyrolysis reaction stoichiometric coefficients for high-temperature combustion of two fuels, namely Jet-A and n-heptane, using a 47 species mechanism. It was found that optimizing on experimental ignition delay and laminar flame speed targets yield better agreement for ignition delay times and flame speeds than optimizing on pyrolysis yield targets alone. For Jet-A, good agreement for ignition delays and flame speeds were obtained by using both ignition delay and flame speeds as targets. For n-heptane, a trade-off between ignition delay and flame speed was found, where increased target weights for ignition delay resulted in worse flame speed predictions, and visa-versa.

Reduced Chemical Kinetic Models of C1 - C4 Alcohols Using the Alternate Species Elimination Approach

2019 ◽  
Author(s):  
Apeng Zhou ◽  
Shirin Jouzdani ◽  
Ben Akih-Kumgeh
Keyword(s):  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Chemical Kinetic Model ◽  
Detailed Model ◽  
Elementary Reactions ◽  
Reduced Models ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

Abstract This study presents four separate reduced chemical kinetic models of methanol/ethanol, propanol isomers, n- and iso-butanol, and n- and s-butanol isomers, derived from a comprehensive chemical kinetic model of C1-C5 alcohols using the Alternate Species Elimination approach. It is motivated by complexity of the detailed model (comprising 600 species and 4100 elementary reactions) and the need for simpler kinetic models for analysis of combustion of smaller alcohols. The reduced models are obtained on the basis of ignition delay time simulations with imposed thresholds on the resulting normalized changes in ignition delay times. The following reduced models are obtained: methanol/ethanol: 38 species and 197 reactions; propanol isomers: 68 species and 419 reactions; n- and iso-butanol: 140 species and 745 reactions; and n- and s-butanol: 134 species and 739 reactions. Predictions of ignition delay times by the reduced models are found to be in good with the detailed models. The reduced models are further tested against other relevant combustion properties. These properties include burning velocities of laminar premixed flames, global pyrolysis time scales, and heat release timing in Homogeneous Charge Compression Ignition engines. This verification shows that reduced models can replace the comprehensive model in combustion analysis without loss of predictive performance. The reduced models can also serve as starting models for developing combined chemical kinetic models of gasoline/diesel and alcohol blends.

Alternative Fuels Based on Biomass: An Experimental and Modeling Study of Ethanol Co-Firing to Natural Gas

2014 ◽  
Author(s):  
Marina Braun-Unkhoff ◽  
Jens Dembowski ◽  
Jürgen Herzler ◽  
Jürgen Karle ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Kinetic Modeling ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Parameter Range ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

In response to the limited resources of fossil fuels as well as to their combustion contributing to global warming through CO2 emissions, it is currently discussed to which extent future energy demands can be satisfied by using biomass and biogenic by-products, e.g. by co-firing. However, new concepts and new unconventional fuels for electric power generation require a re-investigation of at least the gas turbine burner if not the gas turbine itself to ensure a safe operation and a maximum range in tolerating fuel variations and combustion conditions. Within this context, alcohols, in particular ethanol, are of high interest as alternative fuel. Presently, the use of ethanol for power generation — in decentralized (micro gas turbines) or centralized gas turbine units, neat, or co-fired with gaseous fuels like natural gas and biogas — is discussed, besides its role within the transport sector. Chemical kinetic modeling has become an important tool for interpreting and understanding the combustion phenomena observed; for example, focusing on heat release (burning velocities) and reactivity (ignition delay times). Furthermore, a chemical kinetic reaction model validated by relevant experiments performed within a large parameter range allows a more sophisticated computer assisted design of burners as well as of combustion chambers, when used within CFD (computational fluid dynamics) codes. Therefore, a detailed experimental and modeling study of ethanol co-firing to natural gas will be presented focusing on two major combustion properties within a relevant parameter range: (i) ignition delay times measured in a shock tube device, at ambient (p = 1 bar) and elevated (p = 4 bar) pressures, for lean (φ = 0.5) and stoichiometric fuel-air mixtures, and (ii) laminar flame speed data at several preheat temperatures, also for ambient and elevated pressure, gathered from literature. Chemical kinetic modeling will be used for an in-depth characterization of ignition delays and flame speeds at technical relevant conditions. An extensive database will be presented identifying the characteristic differences of the combustion properties of natural gas, ethanol, and ethanol co-fired to natural gas.

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