Dynamic Analysis of a Planar SOFC Stack Fuelled by Biogas

2010 ◽  
Author(s):  
A. Salogni ◽  
D. Alberti
Keyword(s):  
Steady State ◽  
Dynamic Behaviour ◽  
Gaseous Mixture ◽  
Control Device ◽  
Organic Substrate ◽  
Pig Manure ◽  
Biological Degradation ◽  
Internal Reforming ◽  
Pure Methane ◽  
Catalytic Burner

This paper analyzes the dynamic behaviour of a 50 kW stack using planar co-flow solid oxide fuel cells with direct internal reforming fuelled by a biologically derived gaseous mixture of methane and carbon dioxide. The system modelled is composed by the SOFC stack, a catalytic burner, the heat recovery system and the control device aimed to keep the air temperature at the stack exit and the fuel utilization near to the set values. The model has been implemented using standard and user-defined components of an a-causal software based on the open-source Modelica modelling language. After a brief introduction to the production of the gaseous fuel derived from the anaerobic digestion of pig manure, data obtained from a case study on a pig farm situated in Lombardia (Italy) are presented, focusing on the yield of methane which can be exploited. The steady-state performance of the SOFC system fuelled by pure methane are compared with those obtained for the biogas working conditions, showing that the stack voltage is affected by greater concentration losses. Then, starting from a steady-state delivered current of 750 mA cm−2, the dynamic behaviour of the system when a load change of −150 mA cm−2 occurs is investigated for both pure methane and biogas fuelling hypothesis. The results of the simulations show that the transient phase is only marginally affected by the composition of the fuel, which causes a delay of about 50 s in the voltage transient. Finally, the effect obtained by imposing a linear variation in the fuel composition, which can be representative of a modification in the biological degradation of the organic substrate within the anaerobic digester, is discussed. After an initial transient, which is comparable with that obtained for a variation in the load current, the SOFC system is capable to restore the initial delivered power, provided that the required amount of fuel can be supplied to the anode.

Calculation of Organic Substrate Decomposition in Biofilm and Bioreactor-Filter Taking into Account its Limitation and Inhibition

2021 ◽  
pp. 75-77
Author(s):  
Vadim Poliakov
Keyword(s):  
Steady State ◽  
Technological Process ◽  
Mathematical Problem ◽  
Approximate Solutions ◽  
Organic Substrate ◽  
Output Characteristics

The mathematical problem of the steady-state biofiltration of an organic substrate is formulated at two levels  taking into account the limitation and inhibition of the rate of its decomposition. The exact and approximate solutions to the problem of substrate biooxidation in a representative biofilm were obtained and compared using test examples. Based on them an analysis of the technological process in the porous biofilter medium and the output characteristics was carried out.

Steady-State and Dynamic Behaviour of Multi-Recess Hybrid Oil Journal Bearings

1979 ◽  
Vol 21 (5) ◽  
pp. 345-351 ◽  
Author(s):  
M. K. Ghosh ◽  
B. C. Majumdar ◽  
J. S. Rao
Keyword(s):  
Perturbation Theory ◽  
Steady State ◽  
Theoretical Analysis ◽  
Dynamic Behaviour ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Time Dependent ◽  
Damping Coefficients ◽  
Stiffness And Damping

A theoretical analysis of the steady-state and dynamic characteristics of multi-recess hybrid oil journal bearings is presented. A perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term. Load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.

Sebatian Metoksiaromatik Sebagai Substrat Pertumbuhan dan Pengaruh Enzim Demetilase dalam Acetobacterium Woodii DSM 1030

2012 ◽  
Author(s):  
Mohd. Sahaid Hj. Kalil ◽  
Muhammad Zaki ◽  
Wan Mohtar Wan Yusoff ◽  
Mohammad Ramlan Mohd. Salleh
Keyword(s):  
Growth Rate ◽  
Steady State ◽  
Sole Carbon Source ◽  
Specific Growth ◽  
Chemostat Culture ◽  
Carbon Sources ◽  
Syringic Acid ◽  
Organic Substrate ◽  
Acetobacterium Woodii ◽  
Vanilic Acid

Penyelidikan ini bertujuan untuk menyaring substrat organik bagi untuk penghasilan sel–sel A. woodii teraruh demetilase. Pertumbuhan A. woodii dilakukan dalam medium “Balch” yang mengandungi sumber karbon berbeza dalam keadaan anaerobik. Sebanyak sebelas substrat telah diuji iaitu anisol, 2– dan 3–metoksifenol, asid vanilik, asid siringik, asid 2,3,4–, 2,4,5– dan 3,4,5–trimetoksi benzoik, 2,3,4–, 2,4,5– dan 3,4,5–trimetoksi benzil alkohol. 2–metoksifenol merupakan substrat terbaik untuk pertumbuhan A. woodii pada kadar pertumbuhan spesifik 0.14 j–1. Penghasilan sel–sel teraruh demetilase dilakukan dalam kultur kemostat pada kadar pencairan (D) 0.0j–1. Sel-sel pada keadaan mantap dituai dalam keadaan anaerobik dan dipekatkan sebelum digunakan. Pertumbuhan A. woodii didapati maksimum dengan menggunakan kepekatan 0.62 g/L 2–metoksifenol sebagai sumber karbon tunggal. Tindak balas penyahmetilan oleh sel–sel A. woodii meningkat sebanyak 78% apabila 2–metoksifenol sebanyak 0.31 g/L ditambah dalam medium yang mengandungi fruktosa (1% w/v) semasa kultur kemostat. Kata kunci: tindak balas penyahmetilan; demetilase; sel-sel tertuai; metosiaromatik, Acetobacteriumwoodii The objective of this project was to screen organic substrate suitable for the growth of A. woodii, and as for the production of demethylase. A. woodii was grown in “Balch” medium containing different carbon sources. Eleven substrates were tested including anisole, 2– and 3–methoxyphenol, vanilic acid, syringic acid, 2,3,4–, 2,4,5– and 3,4,5–trimethoxy benzoic acid and 2,3,4–, 2,4,5– and 3,4,5–trimethoxy benzyl alcohol. It was found that 2–methoxyphenol was the best substrate with a specific growth rate of 0.14 h–1. The production of demethylase induced cells was carried out in a chemostat culture at a dilution rate (D) of 0.08 h–1. Cells were harvested at steady state of growth and concentrated before use. Optimal concentration of 2–methoxvphenol as the sole carbon source was 0.62 g/L. Demethylation reaction of 0.31 g/L 2–methoxyphenol by induced culture increases 78% relative to the chemostat culture containing only fructose. Key words: Demethylation reaction; demethylase; harvested cells; methoxyaromatic; Acetobacteriumwoodii

Steady-State Theoretical Model of an Electro-Hydraulic Single-Disk Pilot Valve

1992 ◽  
Vol 114 (2) ◽  
pp. 293-298 ◽  
Author(s):  
Y. Sun ◽  
G. A. Parker
Keyword(s):  
Steady State ◽  
Theoretical Model ◽  
Experimental Verification ◽  
Control Device ◽  
Null Condition ◽  
Electromagnetic Model ◽  
Disk Valve ◽  
Single Disk ◽  
Electromagnetic Characteristics ◽  
Pilot Valve

The paper describes an electro-hydraulic single floating-disk valve suitable for use as a pilot control device. For this type of application proportional action involving small movements of the disk for the null condition is required. The theory for the steady-state linearized analysis of both the fluid and electromagnetic characteristics is developed. Experimental verification of the electromagnetic model is also described.

scholarly journals Numerical Prediction of the Dynamic Behaviour of Turbulent Diffusion Flames

1996 ◽  
Author(s):  
Dieter Bohn ◽  
Gregor Deutsch ◽  
Uwe Krüger
Keyword(s):  
Steady State ◽  
Frequency Response ◽  
Turbulent Diffusion ◽  
Dynamic Behaviour ◽  
Diffusion Flames ◽  
Sudden Change ◽  
Combustion Process ◽  
Turbulent Diffusion Flames ◽  
Time Element ◽  
Flame Behaviour

Environmental compatibility requires low emission burners for gas turbine power plants as well as for jet engines. In the past significant progress has been made developing low NOx and CO burners. Unfortunately these burners often have a more pronounced tendency than conventional burner designs to produce combustion driven oscillations The oscillations may be excited to such an extent that pronounced pulsation may possibly occur; this is associated with a risk of engine failure. The stability of a burner system can be investigated by means of a stability analysis under the assumption of acoustical behaviour. The problem with all these algorithms is the transfer function of the flame. A new method is presented here to predict the dynamic flame behaviour by means of a full Navier-Stokes-simulation of the complex combustion process. The first step is to get a steady-state solution of a flame configuration. After that a transient simulation follows with a sudden change in the mass flow rate at the flame inlet. The time-dependent answer of the flame to this disturbance is then transformed into the frequency space by a Laplace Transformation. This leads, in turn, to the frequency response representing the dynamic behaviour of the flame. In principle, this method can be adapted for both diffusion as well as premixed flame systems. However, due to the fact that diffusion flames are more controlled by the mixing process than by the chemical kinetic, the method has first been used for the prediction of the dynamic behaviour of turbulent diffusion flames. The combustion has been modelled by a mixed-is-burnt model. The influence of the turbulence has been taken into account by a modified k-ε-model and the turbulence influences the combustion rate by presumed probability density functions (pdf). The steady-state as well as the transient results have been compared with experimental data for two different diffusion flame configurations. Although the burner configuration is relatively complex, the steady state results collaborate very well with the experiments for velocity, temperature and species distribution. The most important result is that the heat release which drives the oscillations can be modelled sufficiently accurately. The effect of using different pdf-models has been discussed and the best model has been used for the transient calculations of the dynamic flame behaviour. The results for the frequency response of the flame are very encouraging. The principal behaviour of the flame — higher order time element with a delay time — can be predicted with sufficient precision. In addition, the qualitative results collaborate fairly well with the experiments.

Dynamic Analysis and Control of a Planar IT-SOFC System

2009 ◽  
Author(s):  
A. Salogni ◽  
P. Iora ◽  
S. Campanari
Keyword(s):  
Steady State ◽  
Fuel Cell ◽  
Dynamic Model ◽  
Characteristic Curve ◽  
Cell System ◽  
Internal Reforming ◽  
Internal Cell ◽  
Layer Region ◽  
Air Channels ◽  
And Control

This paper analyzes the dynamic behaviour of a 5 kW fuel cell system based on planar co-flow Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) stack, with internal reforming. The system is composed by the SOFC stack, a combustor of the cell exhausts, two heat exchangers for fuel and air preheating and the related control valves, where the air temperature at the stack exit and the fuel utilization is controlled by means of a PI (proportional integral) device. The model of the stack is based on a lumped parameters dynamic model of a single cell, which is composed of the fuel and air channels, the electrochemically active three layer region representative of the anode, the cathode and the electrolyte. The stack model is first used here for a qualitative steady-state validation, reproducing the cell characteristic curve. Then it is presented the dynamic model of the system, which has been implemented using an a-causal software based on the open-source Modelica modelling language, which allows for future integration in complex power-plant configurations. After a description of the plant layout and of the dynamic model, we present and discuss the results obtained by applying the PI controls to different load changes and with different tuning of the controller parameters, evidencing the amplitudes of load changes, the extent of the transient phase to the new steady-state conditions, the internal cell temperature distribution and the thermal gradients along the PEN structure, giving the possibilities to adapt the control system to the requirements of specific SOFC technologies.

Magnetostrictive Terfenol-D Material Linear Simulation Using a Coupled FE-BEM

2004 ◽  
Vol 261-263 ◽  
pp. 555-560
Author(s):  
Soon Suck Jarng ◽  
Je Hyeng Lee ◽  
Y.J. Kwon
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Boundary Element Method ◽  
Harmonic Analysis ◽  
Electric Current ◽  
Dynamic Behaviour ◽  
Helical Coil ◽  
Linear Dynamic ◽  
Resonance Response ◽  
Element Boundary

This paper describes the application of the coupled FE-BEM (finite element-boundary element method) for the numerical harmonic analysis of the linear dynamic behaviour of a magnetostrictive Terfenol-D rod in water. The magnetostrictive rod is three-dimensionally modeled to transduce applied electric current in a helical coil around the rod to mechanical displacement. The steady-state resonance response of the displacement is shown.

Studies on Two-Dimensional Contouring of High-Lift Turbine Airfoil Suction Surface as Separation-Control Device: Separation Suppression Under Steady-State Flow Conditions

2011 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Nozomi Tanaka ◽  
Takahiro Shiba ◽  
Haruyuki Tanimitsu ◽  
Masaaki Hamabe
Keyword(s):  
Steady State ◽  
Separation Bubble ◽  
Control Device ◽  
Surface Boundary ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Steady State Flow ◽  
Suction Surface ◽  
Airfoil Surface ◽  
State Flow

The study the present authors have been working on is to develop a new method to increase aerodynamic loading of low-pressure turbine airfoils for modern aeroengines to a great extent, which is to achieve drastic reduction of their airfoil counts. For this purpose, this study proposes two-dimensional contouring of the airfoil suction surface as a device to suppress the separation bubble that causes large aerodynamic loss, especially at low Reynolds number condition. The main objective of this paper is to show how and to what extent the surface contouring without any other disturbances affects the suction surface boundary layer accompanying separation bubble. For comparison, rather conventional tripping wire technique is also employed as “local 2D surface contouring” to generate flow disturbances in order to suppress the separation bubble. All measurements are carried out under steady-state flow conditions with low freestream turbulence. It turns out from the detailed experiments and LES analysis that the newly proposed two-dimensional contouring of the airfoil surface can effectively suppress the separation bubble, resulting in significant improvement of cascade aerodynamic performance.

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