A machine-learning reduced kinetic model for H2S thermal conversion process

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Anna Dell’Angelo ◽  
Ecem Muge Andoglu ◽  
Suleyman Kaytakoglu ◽  
Flavio Manenti
Keyword(s):  
Kinetic Model ◽  
Kinetic Scheme ◽  
Thermal Conversion ◽  
Operating Conditions ◽  
Thermal Processes ◽  
Proposed Model ◽  
Wide Range ◽  
Commercial Process ◽  
Detailed Kinetic Model

Abstract H2S is becoming more and more appealing as a source for hydrogen and syngas generation. Its hydrogen production potential is studied by several research groups by means of catalytic and thermal conversions. While the characterization of catalytic processes is strictly dependent on the catalyst adopted and difficult to be generalized, the characterization of thermal processes can be brought back to wide-range validity kinetic models thanks to their homogeneous reaction environments. The present paper is aimed at providing a reduced kinetic scheme for reliable thermal conversion of H2S molecule in pyrolysis and partial oxidation thermal processes. The proposed model consists of 10 reactions and 12 molecular species. Its validation is performed by numerical comparisons with a detailed kinetic model already validated by literature/industrial data at the operating conditions of interest. The validated reduced model could be easily adopted in commercial process simulators for the flow sheeting of H2S conversion processes.

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

A predictive combustion model for one-dimensional gasoline engine simulation

2020 ◽  
pp. 146808742094590
Author(s):  
Yoshihiro Nomura ◽  
Seiji Yamamoto ◽  
Makoto Nagaoka ◽  
Stephan Diel ◽  
Kenta Kurihara ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Early Stage ◽  
Burning Velocity ◽  
Turbulent Flame ◽  
Operating Conditions ◽  
Combustion Model ◽  
One Dimensional ◽  
Turbulent Reynolds Number ◽  
Proposed Model ◽  
Wide Range

A new predictive combustion model for a one-dimensional computational fluid dynamics tool in the multibody dynamics processes of gasoline engines was developed and validated. The model consists of (1) a turbulent burning velocity model featuring a flame radius–based transitional function, steady burning velocity that considers local quenching using the Karlovitz number and laminarization by turbulent Reynolds number, as well as turbulent flame thickness and its quenching model near the liner wall, and (2) a knock model featuring auto-ignition by the Livengood–Wu integration and ignition delay time obtained using a full-kinetic model. The proposed model and previous models were verified under a wide range of operating conditions using engines with widely different specifications. Good agreement was only obtained for combustion characteristics by the proposed model without requiring individual calibration of model constants. The model was also evaluated for utilization after prototyping. Improved accuracy, especially of ignition timing, was obtained after further calibration using a small amount of engine data. It was confirmed that the proposed model is highly accurate at the early stage of the engine development process, and is also applicable for engine calibration models that require higher accuracy.

scholarly journals An experimental, theoretical and kinetic-modeling study of the gas-phase oxidation of ammonia

2020 ◽  
Vol 5 (4) ◽  
pp. 696-711 ◽  
Author(s):  
Alessandro Stagni ◽  
Carlo Cavallotti ◽  
Suphaporn Arunthanayothin ◽  
Yu Song ◽  
Olivier Herbinet ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Gas Phase ◽  
Theoretical Investigation ◽  
Kinetic Modeling ◽  
Ammonia Gas ◽  
Wide Range ◽  
Phase Oxidation ◽  
Detailed Kinetic Model ◽  
Gas Phase Oxidation ◽  
Modeling Study

A wide-range experimental and theoretical investigation of ammonia gas-phase oxidation is performed, and a predictive, detailed kinetic model is developed.

scholarly journals Solution Polymerization of Acrylic Acid Initiated by Redox Couple Na-PS/Na-MBS: Kinetic Model and Transition to Continuous Process

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 850
Author(s):  
Federico Florit ◽  
Paola Rodrigues Bassam ◽  
Alberto Cesana ◽  
Giuseppe Storti
Keyword(s):  
Kinetic Model ◽  
Acrylic Acid ◽  
Continuous Process ◽  
Scale Up ◽  
Tubular Reactor ◽  
Kinetic Scheme ◽  
Redox Couple ◽  
Polymerization Process ◽  
Proposed Model ◽  
Population Balances

This work aims at modeling in detail the polymerization of non-ionized acrylic acid in aqueous solution. The population balances required to evaluate the main average properties of molecular weight were solved by the method of moments. The polymerization process considered is initiated by a persulfate/metabisulfate redox couple and, in particular, the kinetic scheme considers the possible formation of mid-chain radicals and transfer reactions. The proposed model is validated using experimental data collected in a laboratory-scale discontinuous reactor. The developed kinetic model is then used to intensify the discontinuous process by shifting it to a continuous one based on a tubular reactor with intermediate feeds. One of the experimental runs is selected to show how the proposed model can be used to assess the transition from batch to continuous process and allow faster scale-up to industrial scale using a literature approach.

scholarly journals Dehydrogenation of Methylcyclohexane: Parametric Sensitivity of the Power Law Kinetics

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Muhammad R. Usman ◽  
David L. Cresswell ◽  
Arthur A. Garforth
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Power Law ◽  
Operating Conditions ◽  
Nonlinear Dependence ◽  
Power Law Model ◽  
Parametric Sensitivity ◽  
Heterogeneous Catalytic ◽  
Wide Range ◽  
Kinetics Of

For heterogeneous catalytic reactions, the empirical power law model is a valuable tool that explains variation in the kinetic behavior with changes in operating conditions, and therefore aids in the development of an appropriate and robust kinetic model. In the present work, experiments are performed on 1.0 wt% Pt/Al2O3 catalyst over a wide range of experimental conditions and parametric sensitivity of the power law model to the kinetics of the dehydrogenation of methylcyclohexane is studied. Power law parameters such as order of the reaction, activation energy, and kinetic rate constants are found dependent upon the operating conditions. With H2 in the feed, both apparent order of the reaction and apparent activation energy generally increase with an increase in pressure. The results suggest a kinetic model, which involves nonlinear dependence of rate on the partial pressure of hydrogen and adsorption kinetics of toluene or some intermediate.

Constrained-Equilibrium Modeling of Methane Oxidation in Air

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Ghassan Nicolas ◽  
Mohammad Janbozorgi ◽  
Hameed Metghalchi
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Combustion Process ◽  
Rate Equations ◽  
Time Step ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times ◽  
Constrained Equilibrium ◽  
Detailed Kinetic Model

Rate-controlled constrained-equilibrium method has been further developed to model methane/air combustion. A set of constraints has been identified to predict the nonequilibrium evolution of the combustion process. The set predicts the ignition delay times of the corresponding detailed kinetic model to within 10% of accuracy over a wide range of initial temperatures (900 K–1200 K), initial pressures (1 atm–50 atm) and equivalence ratios (0.6–1.2). It also predicts the experimental shock tube ignition delay times favorably well. Direct integration of the rate equations for the constraint potentials has been employed. Once the values of the potentials are obtained, the concentration of all species can be calculated. The underlying detailed kinetic model involves 352 reactions among 60 H/O/N/C1-2 species, hence 60 rate equations, while the RCCE calculations involve 16 total constraints, thus 16 total rate equations. Nonetheless, the constrained-equilibrium concentrations of all 60 species are calculated at any time step subject to the 16 constraints.

scholarly journals Generalized Behavioral Modelling Methodology of Switch-Diode Cell for Power Loss Prediction in Electromagnetic Transient Simulation

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1500
Author(s):  
Yanming Xu ◽  
Carl Ngai Man Ho ◽  
Avishek Ghosh ◽  
Dharshana Muthumuni
Keyword(s):  
Power Loss ◽  
Process Analysis ◽  
Operating Conditions ◽  
Transient Simulation ◽  
Oxide Semiconductor ◽  
Model Parameters ◽  
Electromagnetic Transient ◽  
Proposed Model ◽  
Wide Range ◽  
Electromagnetic Transient Simulation

Modern wide-bandgap (WBG) devices, such as silicon carbide (SiC) or gallium nitride (GaN) based devices, have emerged and been increasingly used in power electronics (PE) applications due to their superior switching feature. The power losses of these devices become the key of system efficiency improvement, especially for high-frequency applications. In this paper, a generalized behavioral model of a switch-diode cell (SDC) is proposed for power loss estimation in the electromagnetic transient simulation. The proposed model is developed based on the circuit level switching process analysis, which considers the effects of parasitics, the operating temperature, and the interaction of diode and switch. In addition, the transient waveforms of the SDC are simulated by the proposed model using dependent voltage and current sources with passive components. Besides, the approaches of obtaining model parameters from the datasheets are given and the modelling method is applicable to various semiconductors such Si insulated-gate bipolar transistor (IGBT), Si/SiC metal–oxide–semiconductor field-effect transistor (MOSFET), and GaN devices. Further, a multi-dimensional power loss table in a wide range of operating conditions can be obtained with fast speed and reasonable accuracy. The proposed approach is implemented in PSCAD/ Electromagnetic Transients including DC, EMTDC, (v4.6, Winnipeg, MB, Canada) and further verified by the hardware setups including different daughter boards for different devices.

scholarly journals The HyEnD stern hybrid sounding rocket project

2019 ◽  
Author(s):  
M. Kobald ◽  
C. Schmierer ◽  
U. Fischer ◽  
K. Tomilin ◽  
A. Petrarolo ◽  
...  
Keyword(s):  
Rocket Engine ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Sounding Rocket ◽  
Small Scale ◽  
Stable Operation ◽  
Hybrid Rocket ◽  
Wide Range ◽  
Hybrid Rocket Engine

The student team Hybrid Engine Development (HyEnD) of the University of Stuttgart is taking part with the Institute of Space Systems (IRS) in the DLR educational program STERN (Studentische Experimentalraketen). This program supports students at German universities to design, build, and launch an experimental rocket within a 3-year project time frame. HyEnD is developing a hybrid rocket called HEROS (Hybrid Experimental Rocket Stuttgart) with a design thrust of 10 kN, a total impulse of over 100 kN·s, and an expected liftoff weight up to 175 kg. HEROS is planned to be launched in October 2015 from Esrange in Sweden to an expected flight altitude of 40 to 50 km. The current altitude record for amateur rockets in Europe is at approximately 21 km. The propulsion system of HEROS is called HyRES (Hybrid Rocket Engine Stuttgart) and uses a paraffin-based solid fuel and nitrous oxide (N2O) as a liquid oxidizer. The development and the test campaign of HyRES is described in detail. The main goals of the test campaign are to achieve a combustion efficiency higher than 90% and provide stable operation with low combustion chamber pressure fluctuations. The successful design and testing of the HyRES engine was enabled by the evaluation and characterization of a small-scale demonstrator engine. The 500-newton hybrid rocket engine, called MIRAS (MIcro RAkete Stuttgart), has also been developed in the course of the STERN project as a technology demonstrator. During this test campaign, a ballistic characterization of paraffin-based hybrid rocket fuels with different additives in combination with N2O and a performance evaluation were carried out. A wide range of operating conditions, fuel compositions, injector geometries, and engine configurations were evaluated with this engine. Effects of different injector geometries and postcombustion chamber designs on the engine performance were analyzed. Additionally, the appearance of combustion instabilities under certain conditions, their effects, and possible mitigation techniques were also investigated. Concluding, the development and construction of an advanced, lightweight hybrid sounding rocket for the given requirements and budget within the DLR STERN program are described herein. The most important parts include a high thrust hybrid rocket engine, the development of a light weight oxidizer tank, pyrotechnical valves, carbon fiber rocket structure, recovery systems, and onboard electronics.

Significance of biofilm activity in facultative pond design and performance

1995 ◽  
Vol 31 (12) ◽  
pp. 119-128 ◽  
Author(s):  
C. Polprasert ◽  
B. K. Agarwalla
Keyword(s):  
Substrate Utilization ◽  
Operating Conditions ◽  
Type Model ◽  
Diffusion Type ◽  
Substrate Removal ◽  
Proposed Model ◽  
Wide Range ◽  
Suspended Biomass ◽  
Side Walls ◽  
And Performance

Facultative ponds have found wide application in wastewater treatment as an economical systemwhere land area is available at reasonable cost. Different approaches are available in the literature for the design of facultative ponds. Most research have dealt with only suspended biomass and considered it as the major form of biomass responsible for substrate removal. However, the side walls and bottom of the facultative pond can provide support for the growth of attached (biofilm) biomass which also aids in the degradation of organic matters (substrate). This study demonstrates the significance of biofilm biomass growing on the side walls and bottom of these ponds to substrate utilization. A model for substrate utilization in facultative ponds is proposed which encompasses first-order reactions of both suspended and biofilm biomass. The biofilm activity is described with a diffusion type model, while the dispersed flow model is used for the pond hydraulics to include a wide range of pond dimensions and operating conditions. The proposed model, validated with observed data of two full-scale facultative ponds located in Bangkok, Thailand, and in New Mexico, U.S.A., was able to predict effluent BOD5 concentrations of these two ponds reasonably well.

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