CFD Modeling of a Catalytic Flat Plate Fuel Reformer for Hydrogen Generation

2010 ◽  
Author(s):  
Kranthi K. Gadde ◽  
Panini K. Kolavennu ◽  
Susanta K. Das ◽  
K. J. Berry
Keyword(s):  
Flat Plate ◽  
Catalytic Combustion ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Design Parameters ◽  
Practical Implementation ◽  
Channel Height ◽  
Inlet Temperature ◽  
Two Dimensional

In this study, steam reforming of methane coupled with methane catalytic combustion in a catalytic plate reactor is studied using a two-dimensional mathematical model for co-current flow arrangement. A two-dimensional approach makes the model more realistic by increasing its capability to capture the effect of parameters such as catalyst thickness, reaction rates, inlet temperature and velocity, and channel height, and eliminates the uncertainties introduced by heat and mass transfer coefficients used in one-dimensional models. In our work, we simulate the entire flat plate reformer (both reforming side and combustion side) and carry out parametric studies related to channel height, inlet velocities, and catalyst layer thickness that can provide guidance for the practical implementation of such design. The operating conditions chosen make possible a comparison of the catalytic plate reactor and catalytic combustion analysis with the conventional steam reformer. The CFD results obtained in this study will be very helpful to understand the optimization of design parameters to build a first generation prototype.

Modeling of a Catalytic Flat Plate Fuel Reformer for Hydrogen-Rich Reformate Fuel

2013 ◽  
Author(s):  
Susanta K. Das ◽  
Kranthi K. Gadde
Keyword(s):  
Flat Plate ◽  
Catalytic Combustion ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Design Parameters ◽  
Practical Implementation ◽  
Channel Height ◽  
Inlet Temperature ◽  
Optimized Design ◽  
Two Dimensional

In this study, using a two-dimensional computational fluid dynamics (CFD) model with co-current flow arrangement, steam reforming of methane coupled with methane catalytic combustion in a catalytic plate reactor is investigated. The two-dimensional approach makes the model more realistic by increasing its capability to capture the effect of design parameters such as catalyst thickness, reaction rates, inlet temperature and velocity, and channel height, and eliminates the uncertainties introduced by heat and mass transfer coefficients used in one-dimensional models. In our work, we simulate the entire flat plate reformer electro-kinetics and carry out parametric studies related to design matrices that can provide guidance for the practical implementation of such design. The operating conditions are chosen in such a way which makes possible a good comparison of the catalytic plate reactor and catalytic combustion analysis with the conventional steam reformer. The CFD results obtained in this study is very helpful to understand the optimized design parameters to build a first generation prototype.

Performance Evaluation of a Catalytic Flat Plate Fuel Reformer for Hydrogen-Rich Reformate

2013 ◽  
Author(s):  
Susanta K. Das ◽  
K. Joel Berry
Keyword(s):  
Flat Plate ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Design Parameters ◽  
Practical Implementation ◽  
Channel Height ◽  
Inlet Temperature ◽  
Optimized Design ◽  
Two Dimensional ◽  
Transfer Coefficients

A two-dimensional computational fluid dynamics (CFD) model is used for reforming methane with the help of catalytic combustion and reformation in a catalytic flat plate reformer. The two-dimensional approach makes the computational model more realistic by eliminating the uncertainties introduced by heat and mass transfer coefficients used in one-dimensional models. It also increased its capability to capture the effect of design parameters such as catalyst thickness, reaction rates, inlet temperature and velocity, and channel height has on producing high purity reformate gas. In order to carry out parametric studies related to various design parameters, in our present work, we simulate the entire flat plate reformer domain by considering full electro-kinetics that provide guidance for the practical implementation of such design. We chose different designs and operating conditions in such a way which makes possible to build a catalytic flat plate fuel reformer prototype. Based on the CFD results obtained in this study, we built a first generation catalytic flat plate fuel reformer prototype using the optimized design parameters. The performance of the fuel reformer prototype is tested with a 5-cell high temperature PEM fuel cell stack.

Computational Fluid Dynamics Modeling of a Catalytic Flat Plate Fuel Reformer for On-Board Hydrogen Generation

2013 ◽  
Vol 10 (6) ◽  
Author(s):  
Susanta K. Das ◽  
Kranthi K. Gadde
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flat Plate ◽  
Catalytic Combustion ◽  
Cocurrent Flow ◽  
Design Parameters ◽  
Practical Implementation ◽  
Channel Height ◽  
Two Dimensional ◽  
Wgs Reaction

A catalytic flat plate fuel reformer offers better heat integration by combining the exothermic catalytic combustion reaction on one side and the endothermic catalytic reforming reaction on the other side. In this study, steam reforming of natural gas (methane) coupled with a methane catalytic combustion in a catalytic flat plate reformer is studied using a two-dimensional model for a cocurrent flow arrangement. The two-dimensional computational fluid dynamics (CFD) model makes the predictions more realistic by increasing its capability to capture the effect of various design parameters and eliminates the uncertainties introduced by heat and mass transfer coefficients used in one-dimensional models. In our work we simulated the entire catalytic flat plate reformer (both reforming side and combustion side) and carried-out studies related to important design parameters such as channel height, inlet fuel velocities, and catalyst layer thickness that can provide guidance for the practical implementation of such fuel reformer design. The simulated transverse temperature profiles (not shown here due to page limitation) show that there is virtually no heat loss across the plate at the reformer exit. Introduction of a water gas shift (WGS) reaction at the reformer side along with our optimized reformer design parameters decreases the amount of carbon monoxide (CO) almost 90%–98% in the final reformate exiting the reformer as compared to without the WGS reaction. The CFD results obtained in this study will be very helpful to understand the optimization of design parameters to build a first generation prototype.

Experimental Performance Evaluation of a Catalytic Flat Plate Fuel Reformer for Fuel Cell Grade Reformate

2014 ◽  
Author(s):  
Susanta K. Das ◽  
K. Joel Berry
Keyword(s):  
Fuel Cell ◽  
Flat Plate ◽  
Reaction Rates ◽  
Design Parameters ◽  
Channel Height ◽  
Inlet Temperature ◽  
Cfd Model ◽  
Current Voltage ◽  
Study Results ◽  
Current Voltage Characteristics

Compact and efficient fuel reforming system design is a major challenge because of strict requirements of efficient heat distribution on both the reforming and combustion side. As an alternative to traditional packed bed tubular reformers, catalytic flat plate fuel reformer offers better heat integration by combining the combustion reaction on one side and reforming reaction on the other side. In this study, with the help of a two-dimensional computational fluid dynamics (CFD) model, a catalytic flat plate fuel reformer is built and investigated its performance experimentally. The CFD model simulation results help to capture the effect of design parameters such as catalyst layer thickness, reaction rates, inlet temperature and velocity, and channel height. The CFD model study results also help to design and built the actual reformer in such a way that eliminate the limitations or uncertainties of heat and mass transfer coefficients. In our study, we experimentally evaluated the catalytic flat plate fuel reformer performance using natural gas. The effect of reformate gas on the current-voltage characteristics of a 5kW high temperature PEM fuel cell (HTPEMFC) stack is investigated extensively. The results shows that the overall system performance increases in terms of current-voltage characteristics of HTPEMFC while fed with reformate directly from the catalytic flat plate reformer.

Performance Analyses of Photovoltaic Thermal Integrated Concentrator Collector Combined With Single Effect Absorption Cooling Cycle: Constant Flow Rate Mode

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Md. Meraj ◽  
M.E. Khan ◽  
Md. Azhar
Keyword(s):  
Climatic Conditions ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Inlet Temperature ◽  
New Delhi ◽  
Absorption System ◽  
Simulation Code ◽  
Single Effect ◽  
Performance Analyses

Abstract In the present communication, performance analyses of interconnected N number of fully covered semitransparent photovoltaic thermal integrated concentrator collectors combined with single effect vapor absorption refrigeration system have been carried out. The proposed system was analyzed under the constant mass flowrate of collectors’ fluid. Mathematical expressions have also been derived for generator temperature of the absorption unit as a function of both design and operating parameters. Further, simulations have been performed for a typical day of May month of New Delhi climatic conditions. Performance parameters have been evaluated such as collector exit temperature, generator inlet temperature, electrical power output, electrical efficiency, overall thermal energy gain, instantaneous thermal efficiency, overall exergy gain and coefficient of performance of the absorption system. The simulation code has been written in matlab. From the present analyses, the following salient conclusions have been drawn: Operating generator temperature of the absorption system is suitable for five number of photovoltaic thermal-integrated parabolic concentrator collector connected in series. The proposed system will continue operating for 5 h during May month in New Delhi climate conditions. The maximum solar coefficient of performance, refrigeration coefficient of performance, and exergy coefficient of performance are reported as 0.1551, 0.8344, and 0.2697, respectively, for the proposed novel system under given design and operating conditions. Additionally, the effects of other design parameters of this novel system have also been investigated.

Catalytic Combustion Systems for Micro-Scale Gas Turbine Engines

2005 ◽  
Author(s):  
C. M. Spadaccini ◽  
J. Peck ◽  
I. A. Waitz
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Surface Area ◽  
Power Density ◽  
Mass Flow ◽  
Catalytic Combustion ◽  
Reaction Rates ◽  
Design Parameters ◽  
Micro Scale ◽  
Heterogeneous Catalytic

As part of an ongoing effort to develop a micro-scale gas turbine engine for power generation and micropropulsion applications, this paper presents the design, modeling, and experimental assessment of a catalytic combustion system. Previous work has indicated that homogenous gas-phase microcombustors are severely limited by chemical reaction time-scales. Storable hydrocarbon fuels, such as propane, have been shown to blowout well below the desired mass flow rate per unit volume. Heterogeneous catalytic combustion has been identified as a possible improvement. Surface catalysis can increase hydrocarbon-air reaction rates, improve ignition characteristics, and broaden stability limits. Several radial inflow combustors were micromachined from silicon wafers using Deep Reactive Ion Etching (DRIE) and aligned fusion wafer bonding. The 191 mm3 combustion chambers were filled with platinum coated foam materials of various porosity and surface area. For near stoichiometric propane-air mixtures, exit gas temperatures of 1100 K were achieved at mass flow rates in excess of 0.35 g/s. This corresponds to a power density of approximately 1200 MW/m3; an 8.5-fold increase over the maximum power density achieved for gas-phase propane-air combustion in a similar geometry. Low order models including time-scale analyses and a one-dimensional steady-state plug-flow reactor model, were developed to elucidate the underlying physics and to identify important design parameters. High power density catalytic microcombustors were found to be limited by the diffusion of fuel species to the active surface, while substrate porosity and surface area-to-volume ratio were the dominant design variables.

CFD Modeling of Flow and Heat Transfer Inside a Liquid-Cooled Exhaust Manifold

2003 ◽  
Author(s):  
Rade Milanovic ◽  
Chenn Q. Zhou ◽  
Jim Majdak ◽  
Robert Cantwell
Keyword(s):  
Heat Transfer ◽  
Flow Property ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Inlet Temperature ◽  
Operational Parameters ◽  
Manifold Optimization ◽  
Parametric Effects ◽  
And Performance

Liquid cooled exhaust manifolds are used in turbo charged diesel and gas engines in the marine and various industrial applications. Performance of the manifold has a significant impact on the engine efficiency. Modifying manifold design and changing operational parameters are ways to improve its performance. With the rapid advance of computer technology and numerical methods, Computational Fluid Dynamics (CFD) has become a powerful tool that can provide useful information for manifold optimization. In this study, commercial CFD software (FLUENT®) was used to analyze liquid cooled exhaust manifolds. Detailed information of flow property distribution and heat transfer were obtained in order to provide a fundamental understanding of the manifold operation. Experimental data was compared with the CFD results to validate the numerical simulation. Computations were performed to investigate the parametric effects of operating conditions (engine rotational speed, coolant flow rate, coolant inlet temperature, exhaust gas inlet temperature, surface roughness of the manifold’s material) on the performance of the manifold. Results were consistent with the experimental observations. Suggestions were made to improve the manifold design and performance.

Catalytic Combustion Systems for Microscale Gas Turbine Engines

2005 ◽  
Vol 129 (1) ◽  
pp. 49-60 ◽  
Author(s):  
C. M. Spadaccini ◽  
J. Peck ◽  
I. A. Waitz
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Surface Area ◽  
Power Density ◽  
Mass Flow ◽  
Catalytic Combustion ◽  
Flow Reactor ◽  
Reaction Rates ◽  
Design Parameters ◽  
Heterogeneous Catalytic

As part of an ongoing effort to develop a microscale gas turbine engine for power generation and micropropulsion applications, this paper presents the design, modeling, and experimental assessment of a catalytic combustion system. Previous work has indicated that homogenous gas-phase microcombustors are severely limited by chemical reaction timescales. Storable hydrocarbon fuels, such as propane, have been shown to blow out well below the desired mass flow rate per unit volume. Heterogeneous catalytic combustion has been identified as a possible improvement. Surface catalysis can increase hydrocarbon-air reaction rates, improve ignition characteristics, and broaden stability limits. Several radial inflow combustors were micromachined from silicon wafers using deep reactive ion etching and aligned fusion wafer bonding. The 191mm3 combustion chambers were filled with platinum-coated foam materials of various porosity and surface area. For near stoichiometric propane-air mixtures, exit gas temperatures of 1100K were achieved at mass flow rates in excess of 0.35g∕s. This corresponds to a power density of ∼1200MW∕m3; an 8.5-fold increase over the maximum power density achieved for gas-phase propane-air combustion in a similar geometry. Low-order models, including time-scale analyses and a one-dimensional steady-state plug-flow reactor model, were developed to elucidate the underlying physics and to identify important design parameters. High power density catalytic microcombustors were found to be limited by the diffusion of fuel species to the active surface, while substrate porosity and surface area-to-volume ratio were the dominant design variables.

scholarly journals Model Based Simulation and Genetic Algorithm Based Optimisation of Spiral Wound Membrane RO Process for Improved Dimethylphenol Rejection from Wastewater

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 595
Author(s):  
Mudhar A. Al-Obaidi ◽  
Alejandro Ruiz-García ◽  
Ghanim Hassan ◽  
Jian-Ping Li ◽  
Chakib Kara-Zaïtri ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Energy Consumption ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Operating Conditions ◽  
Design Parameters ◽  
Channel Height ◽  
Model Based ◽  
Feed Channel ◽  
Membrane Design

Reverse Osmosis (RO) has already proved its worth as an efficient treatment method in chemical and environmental engineering applications. Various successful RO attempts for the rejection of organic and highly toxic pollutants from wastewater can be found in the literature over the last decade. Dimethylphenol is classified as a high-toxic organic compound found ubiquitously in wastewater. It poses a real threat to humans and the environment even at low concentration. In this paper, a model based framework was developed for the simulation and optimisation of RO process for the removal of dimethylphenol from wastewater. We incorporated our earlier developed and validated process model into the Species Conserving Genetic Algorithm (SCGA) based optimisation framework to optimise the design and operational parameters of the process. To provide a deeper insight of the process to the readers, the influences of membrane design parameters on dimethylphenol rejection, water recovery rate and the level of specific energy consumption of the process for two different sets of operating conditions are presented first which were achieved via simulation. The membrane parameters taken into consideration include membrane length, width and feed channel height. Finally, a multi-objective function is presented to optimise the membrane design parameters, dimethylphenol rejection and required energy consumption. Simulation results affirmed insignificant and significant impacts of membrane length and width on dimethylphenol rejection and specific energy consumption, respectively. However, these performance indicators are negatively influenced due to increasing the feed channel height. On the other hand, optimisation results generated an optimum removal of dimethylphenol at reduced specific energy consumption for a wide sets of inlet conditions. More importantly, the dimethylphenol rejection increased by around 2.51% to 98.72% compared to ordinary RO module measurements with a saving of around 20.6% of specific energy consumption.

The Effects of Fuel Composition on Flame Structure and Combustion Dynamics in a Lean Premixed Combustor

2007 ◽  
Author(s):  
Lorenzo Figura ◽  
Jong Guen Lee ◽  
Bryan D. Quay ◽  
Domenic A. Santavicca
Keyword(s):  
Heat Release ◽  
Equivalence Ratio ◽  
Flame Structure ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Fuel Composition ◽  
Two Dimensional ◽  
Inlet Velocity ◽  
Unstable Combustion ◽  
Fuel Mixtures

The stability characteristics of a laboratory-scale lean premixed combustor operating on natural gas - hydrogen fuel mixtures have been studied in a variable length combustor facility. The fuel and air were mixed upstream of the choked inlet to the combustor to eliminate equivalence ratio fluctuations and thereby ensure that the dominant instability driving mechanism was flame-vortex interaction. The inlet velocity, inlet temperature, equivalence ratio and percent hydrogen in the fuel were systematically varied, and at each operating condition the combustor pressure fluctuations were measured as a function of the combustor length. The results are presented in the form of two-dimensional stability maps, which are plots of the normalized rms pressure fluctuation versus the equivalence ratio and the combustor length, for a given inlet temperature, inlet velocity, and fuel mixture. In order to understand the effects of operating conditions and fuel composition on the observed stability characteristics, two-dimensional chemiluminescence images of the flame structure were recorded at all operating conditions and for all fuel mixtures under stable conditions. Changes in the stable flame structure, as characterized by the location of the flame’s “center of heat release”, were found to be consistent with the observed instability characteristics. The location of the flame’s “center of heat release” was found to lie along a single path for all operating conditions and fuel mixtures. It was also observed that there were regions of stable and unstable combustion as one moved along this path. Furthermore it was found that flames having the same “center of heat release” location, but different operating conditions and fuel composition, have very nearly the same flame shape. These results will be useful for developing phenomenological models for predicting unstable combustion.

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