scholarly journals Heat and Mass Transfer during Hydrogen Generation in an Array of Fuel Bars of a BWR Using a Periodic Unit Cell

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
H. Romero-Paredes ◽  
F. J. Valdés-Parada ◽  
G. Espinosa-Paredes
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Fuel Element ◽  
Numerical Simulations ◽  
Heat And Mass Transfer ◽  
Nuclear Reactor ◽  
Hydrogen Generation ◽  
Unit Cell ◽  
Concentration Profiles ◽  
Periodic Unit Cell

This paper presents, the numerical analysis of heat and mass transfer during hydrogen generation in an array of fuel cylinder bars, each coated with a cladding and a steam current flowing outside the cylinders. The analysis considers the fuel element without mitigation effects. The system consists of a representative periodic unit cell where the initial and boundary-value problems for heat and mass transfer were solved. In this unit cell, we considered that a fuel element is coated by a cladding with steam surrounding it as a coolant. The numerical simulations allow describing the evolution of the temperature and concentration profiles inside the nuclear reactor and could be used as a basis for hybrid upscaling simulations.

Numerical Analysis of the Heat and Mass Transfer Characteristics in an Autothermal Methane Reformer

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Joonguen Park ◽  
Shinku Lee ◽  
Sunyoung Kim ◽  
Joongmyeon Bae
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Heat And Mass Transfer ◽  
Steam Reforming ◽  
Space Velocity ◽  
Reaction Model ◽  
Operating Conditions ◽  
Local Thermal Equilibrium ◽  
Inlet Temperature ◽  
Transfer Characteristics

This paper discusses a numerical analysis of the heat and mass transfer characteristics in an autothermal methane reformer. Assuming local thermal equilibrium between the bulk gas and the surface of the catalyst, a one-medium approach for the porous medium analysis was incorporated. Also, the mass transfer between the bulk gas and the catalyst’s surface was neglected due to the relatively low gas velocity. For the catalytic surface reaction, the Langmuir–Hinshelwood model was incorporated in which methane (CH4) is reformed to hydrogen-rich gases by the autothermal reforming (ATR) reaction. Full combustion, steam reforming, water-gas shift, and direct steam reforming reactions were included in the chemical reaction model. Mass, momentum, energy, and species balance equations were simultaneously calculated with the chemical reactions for the multiphysics analysis. By varying the four operating conditions (inlet temperature, oxygen to carbon ratio (OCR), steam to carbon ratio, and gas hourly space velocity (GHSV)), the performance of the ATR reactor was estimated by the numerical calculations. The SR reaction rate was improved by an increased inlet temperature. The reforming efficiency and the fuel conversion reached their maximum values at an OCR of 0.7. When the GHSV was increased, the reforming efficiency increased but the large pressure drop may decrease the system efficiency. From these results, we can estimate the optimal operating conditions for the production of large amounts of hydrogen from methane.

Radiative Non-Coaxial Rotation of Magnetohydrodynamic Newtonian Carbon Nanofluid Flow in Porous Medium with Heat and Mass Transfer Effects

2020 ◽  
Vol 9 (4) ◽  
pp. 321-335
Author(s):  
Wan Nura’in Nabilah Noranuar ◽  
Ahmad Qushairi Mohamad ◽  
Sharidan Shafie ◽  
Ilyas Khan ◽  
Lim Yeou Jiann
Keyword(s):  
Carbon Nanotubes ◽  
Mass Transfer ◽  
Porous Medium ◽  
Heat And Mass Transfer ◽  
Nuclear Reactor ◽  
Volume Fraction ◽  
Heating System ◽  
Transform Method ◽  
Rotation System ◽  
Walled Carbon Nanotubes

Non-coaxial rotation system has encountered in various fields such as engineering field in designing advanced cooling and heating system, food processing and mixer machines. In the present study, the effect of the non-coaxial rotation of a vertical disk on the heat and mass transfer of Newtonian nanofluids in a porous medium is analytically discussed. The influence of the magnetic field and thermal radiation is also taken into the consideration. Two different types of nanofluids which are single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) with water as the base fluid are analyzed and compared. Suitable dimensionless variables are utilized to convert the governing partial differential equations associated with the initial and boundary conditions into the dimensionless form. Then, the exact solutions of the dimensionless governing equations are calculated by using the Laplace transform method. A limiting case study of the obtained analytical solutions is constructed to compare with the previously published results to verify its validity. The distributions of the velocity, temperature, and concentration along with the Skin friction, Nusselt number, and Sherwood number due to the variation of the pertinent parameters are displayed and scrutinized through graphs and tables. In the frame of non-coaxial rotation, the nanofluid with the SWCNTs nanoparticles have illustrated a higher rate of heat transfer as compared to MWCNTs nanofluid. Moreover, the heat transmission in the nanofluid has been enhanced by increasing the volume fraction of the nanoparticle and also the intensity of the radiation. This suggests that heating or cooling in a system such as a nuclear reactor can be improved by properly selecting the type of the nanofluid and also the volume fraction of the nanoparticle.

A numerical analysis of heat and mass transfer processes in a macro-patterned methane/steam reforming reactor

2018 ◽  
Vol 43 (45) ◽  
pp. 20474-20487 ◽  
Author(s):  
Marcin Pajak ◽  
Marcin Mozdzierz ◽  
Maciej Chalusiak ◽  
Shinji Kimijima ◽  
Janusz S. Szmyd ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Heat And Mass Transfer ◽  
Steam Reforming ◽  
Methane Steam Reforming ◽  
Transfer Processes ◽  
Methane Steam ◽  
Mass Transfer Processes
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