scholarly journals Theoretical Study of Palladium Membrane Reactor Performance During Propane Dehydrogenation Using CFD Method

2017 ◽  
Vol 17 (1) ◽  
pp. 113 ◽  
Author(s):  
Kamran Ghasemzadeh ◽  
Milad Mohammad Alinejad ◽  
Milad Ghahremani ◽  
Rahman Zeynali ◽  
Amin Pourgholi
Keyword(s):  
Membrane Reactor ◽  
Fluid Dynamic ◽  
Theoretical Data ◽  
Operating Parameter ◽  
Propane Dehydrogenation ◽  
Propane Conversion ◽  
Hydrogen Yield ◽  
Cfd Model ◽  
Reactor Performance ◽  
Pd Membrane

This study presents a 2D-axisymmetric computational fluid dynamic (CFD) model to investigate the performance Pd membrane reactor (MR) during propane dehydrogenation process for hydrogen production. The proposed CFD model provided the local information of temperature and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of CFD model results was carried out by other modeling data and a good agreement between CFD model results and theoretical data was achieved. Indeed, in the present model, a tubular reactor with length of 150 mm was considered, in which the Pt-Sn-K/Al2O3 as catalyst were filled in reaction zone. Hence, the effects of the important operating parameter (reaction temperature) on the performances of membrane reactor (MR) were studied in terms of propane conversion and hydrogen yield. The CFD results showed that the suggested MR system during propane dehydrogenation reaction presents higher performance with respect to once obtained in the conventional reactor (CR). In particular, by applying Pd membrane, was found that propane conversion can be increased from 41% to 49%. Moreover, the highest value of propane conversion (X = 91%) was reached in case of Pd-Ag MR. It was also established that the feed flow rate of the MR is to be the one of the most important factors defining efficiency of the propane dehydrogenation process.

Modelling Study of Palladium Membrane Reactor Performance during Methan Steam Reforming using CFD Method

2016 ◽  
Vol 11 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Kamran Ghasemzadeh ◽  
Ehsan Andalib ◽  
Angelo Basile
Keyword(s):  
Experimental Data ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Membrane Reactor ◽  
Fluid Dynamic ◽  
Molar Fraction ◽  
Methane Steam Reforming ◽  
Cfd Model ◽  
Palladium Membrane ◽  
Hydrogen Recovery

Abstract The main aim of this study is the investigation of dense palladium membrane reactor (MR) performance during methane steam reforming (MSR) reaction using computational fluid dynamic (CFD). To this purpose, a two-dimensional isothermal CFD model was developed and its validation was realized by comparing the theoretical results with our experimental data achieved in ITM of Italy. In this work, the CFD model was presented by COMSOL- Multiphysics software version 5. The reaction rate expressions and kinetics parameters were used from literatures. According to validation results, a good agreement between modeling results and experimental data was found. After model validation, the effect of the some important operating parameters (temperature and pressure) on the performance of palladium MR was studied in terms of methane conversion and hydrogen recovery. The CFD model presented velocity and pressure profiles in both side of MR and also molar fraction of different species in permeate and retentate streams. The modeling results showed that the palladium MR presents comparable performance with respect to traditional reactor (TR) in terms of the methane conversion, especially, at lower temperatures and higher pressures. In fact, CFD results indicated that palladium MR performance was improved by increasing the reaction pressure, while this parameter had negative effect on the TR performance. This result related to increasing the hydrogen permeance through the palladium membrane by enhancement of pressure gradient. Indeed, this shift effect can provide a higher methane conversion in lower temperatures in the palladium MR. In particular, 99% methane conversion and 43% hydrogen recovery was achieved at 500°C and 1.5 atm.

Dispersion effects on membrane reactor performance

AIChE Journal ◽  
1996 ◽  
Vol 42 (9) ◽  
pp. 2607-2615 ◽  
Author(s):  
M. K. Koukou ◽  
N. Papayannakos ◽  
N. C. Markatos
Keyword(s):  
Membrane Reactor ◽  
Reactor Performance ◽  
Dispersion Effects

CFD Analysis of the Coolant Mixing within the Upper Plenum of a Pressurized Water Reactor (PWR)

2013 ◽  
Vol 444-445 ◽  
pp. 411-415 ◽  
Author(s):  
Fu Cheng Zhang ◽  
Shen Gen Tan ◽  
Xun Hao Zheng ◽  
Jun Chen
Keyword(s):  
Temperature Distribution ◽  
Fluid Dynamic ◽  
Characteristic Temperature ◽  
Reactor Core ◽  
Flow Distribution ◽  
Sensitivity Study ◽  
Cfd Model ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

In this study, a Computational Fluid Dynamic (CFD) model is established to obtain the 3-D flow characteristic, temperature distribution of the pressurized water reactor (PWR) upper plenum and hot-legs. In the CFD model, the flow domain includes the upper plenum, the 61 control rod guide tubes, the 40 support columns, the three hot-legs. The inlet boundary located at the exit of the reactor core and the outlet boundary is set at the hot-leg pipes several meters away from upper plenum. The temperature and flow distribution at the inlet boundary are given by sub-channel codes. The computational mesh used in the present work is polyhedron element and a mesh sensitivity study is performed. The RANS equations for incompressible flow is solved with a Realizable k-ε turbulence model using the commercial CFD code STAR-CCM+. The analysis results show that the flow field of the upper plenum is very complex and the temperature distribution at inlet boundary have significant impact to the coolant mixing in the upper plenum as well as the hot-legs. The detailed coolant mixing patterns are important references to design the reactor core fuel management and the internal structure in upper plenum.

Application of CFD Model for Inlet Flow Region of 17×17 Fuel Assembly

2006 ◽  
Author(s):  
Milorad B. Dzodzo ◽  
Bin Liu ◽  
Pablo R. Rubiolo ◽  
Zeses E. Karoutas ◽  
Michael Y. Young
Keyword(s):  
Fuel Assembly ◽  
Fluid Dynamic ◽  
Flow Distribution ◽  
Flow Region ◽  
Fretting Wear ◽  
Jet Flows ◽  
Cfd Model ◽  
Lateral Velocity ◽  
Fuel Assemblies ◽  
Inlet Conditions

A numerical investigation was performed to study the variation in axial and lateral velocity profiles occurring downstream of the inlet nozzle of a typical Westinghouse 17×17 PWR fuel assembly. A Computational Fluid Dynamic (CFD) model was developed with commercial CFD software. The model comprised the lower region of the fuel assembly, including: the Debris Filter Bottom Nozzle (DFBN), P-grid, Bottom Inconel grid, one and half grid span, as well as the lower core plate hole. The purpose of the study was to obtain insight into the flow redistribution resulting from the interaction of the jet arising from the lower core plate hole and the fuel assembly structure. In particular the axial and lateral velocities before and after the nozzle were studied. The results, axial and lateral velocity contours, streamlines and maximum axial and lateral velocity distributions at various elevations are presented and discussed in relation to the potential risk of high turbulent excitation over the rod and the resulting rod-to-grid fretting-wear damage. The CFD model results indicated that the large jet flows from the lower core plate are effectively dissipated by DFBN nozzle and the grids components of the fuel assembly. The breakup of the large jets in the DFBN and the lower grids helps to reduce the steep velocity gradients and thus the rod vibration and fretting-wear risk in the lower part of the fuel assembly. The presented CFD model is one step towards developing advanced tools that can be used to confirm and evaluate the effect of complex PWR structures on flow distribution. In the future the presented model could be integrated in a larger CFD model involving several fuel assemblies for evaluating the lateral velocities generated due to the non-uniform inlet conditions into the various fuel assemblies.

Raised Floor Computer Data Center: Effect on Rack Inlet Temperatures When Adjacent Racks Are Removed

2003 ◽  
Author(s):  
Roger Schmidt ◽  
Ethan Cruz
Keyword(s):  
Data Center ◽  
Control Volume ◽  
Fluid Dynamic ◽  
Computer Code ◽  
Cfd Model ◽  
Computer Data ◽  
Center Effect ◽  
Air Temperatures ◽  
Baseline Case ◽  
Finite Control

This paper focuses on the effect on inlet rack air temperatures when adjacent racks are removed. Only the above floor (raised floor) flow and temperature distributions were analyzed for various air flowrates exhausting from the perforated tiles and the rack. A Computational Fluid Dynamic (CFD) model was generated for the room with electronic equipment installed on a raised floor with particular focus on the effects on rack inlet temperatures of these high powered racks. The baseline case was with forty racks of data processing (DP) equipment arranged in rows in a data center cooled by chilled air exhausting from perforated floor tiles. The chilled air was provided by four A/C units placed inside a room 12.1 m wide × 13.4 m long. Since the arrangement of the racks in the data center was symmetric only one-half of the data center was modeled. To see the effect of missing racks adjacent to high powered racks various configurations were analyzed. The numerical modeling was performed using a commercially available finite control volume computer code called Flotherm (Trademark of Flomerics, Inc.). The flow was modeled using the k-e turbulence model. Results are displayed to provide some guidance on the design and layout of a data center.

Experimental and Numerical Characterization of an Orifice Type Cryogenic Pulse Tube Refrigerator

2011 ◽  
Author(s):  
Dion Savio Antao ◽  
Bakhtier Farouk
Keyword(s):  
Porous Media ◽  
Heat Exchanger ◽  
Fluid Dynamic ◽  
Travelling Wave ◽  
Cryogenic Cooling ◽  
Energy Separation ◽  
Pulse Tube ◽  
Cfd Model ◽  
Pulse Tube Refrigerator ◽  
Energy Equations

An orifice type pulse tube refrigerator (OPTR) was designed, built and operated to provide cryogenic cooling. The OTPR is a travelling wave thermoacoustic refrigerator that operates on a modified reverse Stirling cycle. We consider a system that is comprised of a pressure wave generator (a linear motor), an aftercooler heat-exchanger, a regenerator (comprising of a porous structure for energy separation), a pulse tube (in lieu of a displacer piston as found in Stirling refrigerators) with a cold and a warm heat-exchanger at its two ends, a needle-type orifice valve, an inertance tube and a buffer volume. The experimental characterization is done at various values of mean pressure of helium (∼ 0.35 MPa–2.2 MPa), amplitude of pressure oscillations, frequency of operation and size of orifice opening. A detailed time-dependent axisymmetric computational fluid dynamic (CFD) model of the OPTR is simulated to predict the performance of the OPTR. In the CFD model, the continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the OPTR. An accurate representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. In the future, a validated computational model can be used for system improvement and optimization.

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