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

Performance Analysis on the Internally Cooled Dehumidifier Using Two Liquid Desiccant Solutions

2012 ◽  
Author(s):  
I. P. Koronaki ◽  
R. I. Christodoulaki ◽  
V. D. Papaefthimiou ◽  
E. D. Rogdakis
Keyword(s):  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer ◽  
Flow Rate ◽  
Air Conditioning ◽  
Cooling Water ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Liquid Desiccant ◽  
Internally Cooled

Liquid desiccant air conditioning systems have recently been attracting attention due to their capability of handling the latent load without super-cooling and then reheating the air, as happens in a conventional compression-type air conditioning system. This paper presents the results from a study of the performance of an internally cooled liquid desiccant dehumidifier. A plate heat exchanger is proposed as the internally cooled element of the dehumidifier and water as the cooling fluid. The desiccant solution is sprayed into the internally cooled dehumidifier from the top and flows down by gravity. At the same time, fresh humid air is blown from the bottom or top, counter-flowing or co-flowing with the desiccant solution. The desiccant is in direct contact with the air, allowing for heat and mass transfer. The cooling water, flowing inside the plates of the dehumidifier, carries out the heat of the crossed air and solution. A heat and mass transfer theoretical model has been developed, based on the Runge-Kutta fixed step method, to predict the performance of the device under various operating conditions. Experimental data from previous literature have been used to validate the model. Excellent agreement has been found between experimental tests and the theoretical model, with the deviation not exceeding ±4.1% for outlet air temperature and ±4.0% for outlet humidity ratio. Following the validation of the mathematical model, the dominating effects on the absorption process have been discussed in detail. Namely, effects of flow configuration, air inlet temperature, humidity and flow rate, as well as desiccant inlet temperature, concentration and flow rate have been investigated against the dehumidification rate and the cooling efficiency. The two most commonly used liquid desiccant solutions, namely LiCl and LiBr have been also evaluated against each other. The results suggested that high dehumidification mass rate can be achieved under counter flow between air and solution, low air mass flow rates, low cooling water temperature, low desiccant temperature and LiCl as the desiccant solution.

Effect of Operating Conditions on Optimal Performance of Rotary Dehumidifiers

1995 ◽  
Vol 117 (1) ◽  
pp. 62-66 ◽  
Author(s):  
W. Zheng ◽  
W. M. Worek ◽  
D. Novosel
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Rotational Speed ◽  
Optimal Performance ◽  
Operating Conditions ◽  
Sorption Properties ◽  
Design Point ◽  
The Real ◽  
Transfer Characteristics ◽  
The Matrix

The design-point dehumidification performance (i.e., at ARI conditions) of a rotary dehumidifier wheel depends on its rotational speed, the sorption properties of the desiccant, the heat and mass transfer characteristics of the matrix, and the size of the dehumidifier. However, the real operating conditions of a rotary dehumidifier can vary significantly from the design point, given the large variations in operating conditions (i.e., the outdoor, indoor, and regeneration temperatures and humidities) for various locations during different times of the year. This paper investigates the variability of the dehumidification performance of a rotary dehumidifier and its dependence on operating conditions. Also, the effect of the operating conditions on the optimum rotational speed of a rotary dehumidifier, where the performance of a rotary dehumidifier is optimized, is described.

A numerical analysis of heat and mass transfer during the steam reforming process of ethane

2017 ◽  
Vol 54 (8) ◽  
pp. 2305-2314 ◽  
Author(s):  
Marcin Tomiczek ◽  
Robert Kaczmarczyk ◽  
Marcin Mozdzierz ◽  
Grzegorz Brus
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Heat And Mass Transfer ◽  
Steam Reforming

Numerical Thermal and Mass Analyses of Autothermal Reformer

2006 ◽  
Author(s):  
Shinku Lee ◽  
Joongmyeon Bae ◽  
Sungkwang Lim
Keyword(s):  
Mass Transfer ◽  
Chemical Reaction ◽  
Steam Reforming ◽  
Operating Conditions ◽  
Local Thermal Equilibrium ◽  
Methane Steam Reforming ◽  
Optimum Operating ◽  
Hydrogen Yield ◽  
Complete Combustion ◽  
High Hydrogen

This paper discusses numerical analysis of heat and mass transfer characteristics in autothermal fuel reformer. Assuming local thermal equilibrium between bulk gas and surface of catalyst, one medium approach for energy equation is incorporated. Also, mass transfer between concentrations of bulk gas and near the surface of catalyst is neglected due to relatively low gas mixture velocity. For surface chemical reaction Langmuir-Hinshelwood reaction is incorporated when methane (CH4) is reformed to hydrogen-rich gases by autothermal reforming (ATR) reaction. Complete combustion, steam reforming, water gas shift and direct methane steam reforming reactions are included in the chemical reaction model. Under two operating conditions (O/C and S/C), ATR reactions are estimated from the numerical calculations. Mass, momentum, and energy equations are simultaneously calculated with chemical reactions. From the predicted results, we can estimate optimum operating conditions for high hydrogen yield.

Sign in / Sign up

Export Citation Format

Share Document