scholarly journals Experimental testing of multi-tubular reactor for hydrogen production and comparison with a thermal CFD model

2018 ◽  
Author(s):  
Elvira Tapia ◽  
Aurelio González-Pardo ◽  
Alfredo Iranzo ◽  
Alfonso Vidal ◽  
Felipe Rosa
Keyword(s):  
Hydrogen Production ◽  
Experimental Testing ◽  
Tubular Reactor ◽  
Cfd Model

scholarly journals Multi-Tubular Reactor for Hydrogen Production: CFD Thermal Design and Experimental Testing

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 31 ◽  
Author(s):  
Elvira Tapia ◽  
Aurelio González-Pardo ◽  
Alfredo Iranzo ◽  
Manuel Romero ◽  
José González-Aguilar ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Experimental Testing ◽  
Tubular Reactor ◽  
Experimental Tests ◽  
Thermal Design ◽  
Thermochemical Cycle ◽  
Cfd Model ◽  
Cfd Modelling ◽  
Solar Reactor ◽  
Computational Fluid Dynamics Cfd

This study presents the Computational Fluid Dynamics (CFD) thermal design and experimental tests results for a multi-tubular solar reactor for hydrogen production based on the ferrite thermochemical cycle in a pilot plant in the Plataforma Solar de Almería (PSA). The methodology followed for the solar reactor design is described, as well as the experimental tests carried out during the testing campaign and characterization of the reactor. The CFD model developed for the thermal design of the solar reactor has been validated against the experimental measurements, with a temperature error ranging from 1% to around 10% depending on the location within the reactor. The thermal balance in the reactor (cavity and tubes) has been also solved by the CFD model, showing a 7.9% thermal efficiency of the reactor. CFD results also show the percentage of reacting media inside the tubes which achieve the required temperature for the endothermic reaction process, with 90% of the ferrite pellets inside the tubes above the required temperature of 900 °C. The multi-tubular solar reactor designed with aid of CFD modelling and simulations has been built and operated successfully.

scholarly journals Flow behaviour of an agitated tubular reactor using a novel dynamic mesh based CFD model

2020 ◽  
Vol 212 ◽  
pp. 115333 ◽  
Author(s):  
Yi He ◽  
Andrew E. Bayly ◽  
Ali Hassanpour ◽  
Michael Fairweather ◽  
Frans Muller
Keyword(s):  
Tubular Reactor ◽  
Flow Behaviour ◽  
Dynamic Mesh ◽  
Cfd Model

Effect of Heat Flux Distribution Profile on Hydrogen Concentration in an Allothermal Downdraft Biomass Gasification Process: Modeling Study

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yuhan A. Lenis ◽  
Gilles Maag ◽  
Celso Eduardo Lins de Oliveira ◽  
Lesme Corredor ◽  
Marco Sanjuan
Keyword(s):  
Heat Flux ◽  
Hydrogen Production ◽  
Power Systems ◽  
Solar Power ◽  
Fixed Bed ◽  
Tubular Reactor ◽  
Total Power ◽  
Distribution Profile ◽  
Detailed Model ◽  
Gasification Process

Considering the potential of using concentrating solar power systems to supply the heat required for the allothermal gasification process, this study analyzes hydrogen production in such a system by assuming typical radiative heat flux profiles for a receiver of a central tower concentrated solar power (CSP) plant. A detailed model for allothermal gasification in a downdraft fixed bed tubular reactor is proposed. This considers solid and gas phases traveling in parallel flow along the reactor. Results for temperature and gas profile show a reasonable quantitative agreement with experimental works carried out under similar conditions. Aiming to maximize H2 yield, eight Gaussian flux distributions, similar to those typical of CSP systems, each with a total power of 8 kW (average heat flux 20 kW/m2), but with varying peak locations, were analyzed. The results show a maximum producer gas yield and a chemical efficiency of 134.1 kmol/h and 45.9% respectively, with a molar concentration of 47.2% CO, 46.9% H2, 3.3% CH4, and 2.6% CO2 for a distribution peak at z = 1.4 m, thus relatively close to the flue gas outlet. Hydrogen production and gas yield using this configuration were 4% and 2.9% higher than the achieved using the same power but homogeneously distributed. Solar to chemical efficiencies ranged from 38.9% to 45.9%, with a minimum when distribution peak was at the reactor center. These results are due to high temperatures during the latter stage of the process favoring char gasification reactions.

scholarly journals CFD Model of a Planar Solid Oxide Electrolysis Cell: Base Case and Variations

2007 ◽  
Author(s):  
Grant Hawkes ◽  
Russell Jones
Keyword(s):  
Hydrogen Production ◽  
Current Density ◽  
Solid Oxide ◽  
Cathode Side ◽  
Base Case ◽  
Electrolysis Cell ◽  
Gas Composition ◽  
Cfd Model ◽  
Solid Oxide Electrolysis ◽  
Solid Oxide Electrolysis Cell

A three-dimensional computational fluid dynamics (CFD) model has been created to model high-temperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell, as it would exist in an electrolysis stack. Details of the model geometry are specific to a stack that was fabricated by Ceramatec, Inc. and tested at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) module adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with experimental results obtained from an actual ten-cell stack tested at INL. Mean per-cell area-specific-resistance (ASR) values decrease with increasing current density, consistent with experimental data. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, cathode and anode exchange current density, and contact resistance from the base case are presented. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.

Hydrogen production from glycerol by supercritical water gasification in a continuous flow tubular reactor

2012 ◽  
Vol 37 (7) ◽  
pp. 5559-5568 ◽  
Author(s):  
Simao Guo ◽  
Liejin Guo ◽  
Changqing Cao ◽  
Jiarong Yin ◽  
Youjun Lu ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Supercritical Water ◽  
Continuous Flow ◽  
Tubular Reactor ◽  
Supercritical Water Gasification

Optimization of the Straight-Through Labyrinth Seal With a Smooth Land

2018 ◽  
Author(s):  
Włodzimierz Wróblewski ◽  
Daniel Frączek ◽  
Artur Szymański ◽  
Krzysztof Bochon ◽  
Sławomir Dykas ◽  
...  
Keyword(s):  
Discharge Coefficient ◽  
Experimental Testing ◽  
High Capacity ◽  
Labyrinth Seal ◽  
Response Surfaces ◽  
Measuring System ◽  
Cfd Model ◽  
Test Rig ◽  
Ansys Cfx ◽  
Wide Range

The primary goal of this study was to develop and experimentally validate the methodology of labyrinth seals optimization concerning leakage. The problem was investigated using the ANSYS CFX commercial software. This paper presents the methodology and results of the optimization of a straight-through labyrinth seal with two inclined fins against smooth-land. The optimization was performed using commercial tools implemented in the ANSYS Workbench environment, such as Goal-Driven Optimization (GDO). The response surfaces were created based on Latin hypercube samples found from CFD calculations. The CFD solver — Ansys CFX, using a steady-state scheme with the k-omega Shear Stress Transport turbulence model, was applied. The CFD model was previously validated concerning spatial discretisation and turbulence modelling. A screening algorithm was used to find the best candidates on the response surfaces. The objective function adopted in the labyrinth seal optimization was the minimization of the discharge coefficient value. A wide range of parameters of the fins position and shape, such as the angles, heights and widths, were taken into account, with physically justified degrees of freedom. The leakage reductions being the effect of the optimization were considerable. The cuts in the discharge coefficient significantly exceed the uncertainties of the CFD model and the test rig accuracy. The factors that have the strongest impact on the leakage reduction in are the inclination, thickness of the fin tips, and the distance between fins. The optimization results were supported with the results of an in-house experiment performed on a stationary, linear test rig. The specimens tested experimentally were on the same scale (1:1) as the optimised ones. The test rig was fed by a high-capacity vacuum air blower, which made it possible to reach critical pressure ratios, with high-precision hot wire anemometry (HWA) mass flow evaluation. The measuring system also enabled assessment of the pressure distribution along the labyrinth structure. The experimental testing results were compared to the CFD calculations and the optimization effects, highlighting some specific tendencies in the labyrinth seal flow behaviour. Good agreement was obtained between the optimization results and the experimental data, which proves that the presented methodology is sufficient for the labyrinth seal optimization. The same methods will also be applied to more sophisticated sealing structures.

scholarly journals Spatial and Temporal Validation of a CFD Model Using Residence Time Distribution Test in a Tubular Reactor

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 94
Author(s):  
José Rivas ◽  
M. Constanza Sadino-Riquelme ◽  
Ignacio Garcés ◽  
Andrea Carvajal ◽  
Andrés Donoso-Bravo
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Fluid Dynamic ◽  
Tubular Reactor ◽  
Temporal Distribution ◽  
Cfd Model ◽  
Ansys Fluent ◽  
Cfd Models ◽  
Temporal Validation

Computational fluid dynamic (CFD) has been increasingly exploited for the design and optimization of (bio)chemical processes. Validation is a crucial part of any modeling application. In CFD, when validation is done, complex and expensive techniques are normally employed. The aim of this study was to test the capability of the CFD model to represent a residence time distribution (RTD) test in a temporal and spatial fashion inside a reactor. The RTD tests were carried out in a tubular reactor operated in continuous mode, with and without the presence of artificial biomass. Two hydraulic retention times of 7.2 and 13 h and superficial velocities 0.65, 0.6, 1.3, and 1.1 m h−1 were evaluated. As a tracer, an aqueous solution of methylene blue was used. The CFD model was implemented in ANSYS Fluent, and to solve the equations system, the SIMPLE scheme and second-order discretization methods were selected. The proposed CFD model that represents the reactor was able to predict the spatial and temporal distribution of the tracer injected in the reactor. The main disagreements between the simulations and the experimental results were observed, especially in the first 50 min of the RTD, caused by the different error sources, associated to the manual execution of the triplicates, as well as some channeling or tracer by-pass that cannot be predicted by the CFD model. The CFD model performed better as the time of the experiment elapsed for all the sampling ports. A validation methodology based on an RTD by sampling at different reactor positions can be employed as a simple way to validate CFD models.

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