Numerical Analysis of the Flow Characteristics and Heat and Mass Transfer of Falling-Water Films in an Industrial-Scale Dip Tube of a WSCC in an OMB Gasifier

2013 ◽  
Vol 52 (26) ◽  
pp. 9295-9300 ◽  
Author(s):  
Yifei Wang ◽  
Qiangqiang Guo ◽  
Bihua Fu ◽  
Jiangliang Xu ◽  
Guangsuo Yu ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Heat And Mass Transfer ◽  
Flow Characteristics ◽  
Industrial Scale ◽  
Water Films

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.

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

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.

Study Advancement for Multiphase Flow and Heat and Mass Transfer Characteristics for Gas Hydrate Decomposition in South China Sea Offshore Sediment

2013 ◽  
Author(s):  
Xichong Yu ◽  
Jiafei Zhao ◽  
Weixin Pang ◽  
Gang Li ◽  
Yu Liu
Keyword(s):  
Mass Transfer ◽  
Multiphase Flow ◽  
Heat And Mass Transfer ◽  
Gas Hydrate ◽  
Flow Characteristics ◽  
Decomposition Process ◽  
Lattice Boltzmann Model ◽  
Experimental Simulation ◽  
Hydrate Decomposition ◽  
Multi Phase Flow

Gas hydrates are crystalline solids that consist of gas molecules, usually methane, surrounded by water molecules. According to the phase equilibrium characteristics of gas hydrate, there are three basic development methods, including heating, pressure decreasing and chemical injecting. The development process is actually the multi-phase flow process. Currently, there is no good commercial software used to simulate the multiphase flow, heat transmission and mass transfer in the gas hydrate decomposition process. The study is not mature, still in the development and trial stage. So in this paper, we will make a deeply study on the multi-phase flow simulation method of gas hydrate decomposition in the sediment. We try to make breakthrough in the theory and simulate method. According to the different scales, the simulation computation study of flow characteristics model has microcosmic, mesocosmic and macrocosmic scales. In this paper, mesocosmic scales is used to study for the multiphase flow, heat and mass transfer in the offshore gas hydrate decomposition process, and numerical simulation and experimental simulation are together used to study. Study advancements are shown as follows: firstly, conventional Lattice Boltzmann model is modified to new Lattice Boltzmann Model (LBM) based on sediment with gas hydrate and flow characteristics for gas hydrate decomposition, the interaction and density difference between the phases are considered, and Magnetic Resonance Imaging (MRI) visual technology is used to successfully verified to LBM methods. Secondly, contraction core reaction methods based on fractal theory is used to simulate heat and mass transfer in the offshore gas hydrate decomposition process and is successfully verified by experimental simulation for South China Sea offshore gas hydrate sediment.

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