Modeling Heat and Mass Transfer Correlations for Flow Through Micro Channels in Monolith Honeycomb Catalytic Combustor

2009 ◽  
Author(s):  
Juan Yin ◽  
Yi-wu Weng
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Catalytic Combustion ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Predicting Performance ◽  
Micro Channels ◽  
Characteristics Analysis ◽  
Flow Through ◽  
Catalytic Combustor

This paper investigated performance characteristics analysis of catalytic combustion by utilizing 1-D models incorporated heat and mass transfer correlations. The 1-D numerical results were compared with 2-D models studies and experimental data. The performance characteristics were mainly the effects of operating conditions on methane conversion rate. The comparable analysis confirmed that 1-D model can success in predicting performance of catalytic combustion when empiric inter-phase heat and mass transfer correlations are used and appropriate operating conditions are chosen.

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.

Heat and mass transfer effects on MHD non-Newtonian fluids flow through an inclined thermally-stratified porous medium

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gladys Tharapatla ◽  
Pamula Rajakumari ◽  
Ramana G.V. Reddy
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Velocity Profile ◽  
Heat And Mass Transfer ◽  
Newtonian Fluids ◽  
Transfer Effects ◽  
Content Type ◽  
Non Linear ◽  
Homotopy Analysis ◽  
Flow Through

Purpose This paper aims to analyze heat and mass transfer of magnetohydrodynamic (MHD) non-Newtonian fluids flow past an inclined thermally stratified porous plate using a numerical approach. Design/methodology/approach The flow equations are set up with the non-linear free convective term, thermal radiation, nanofluids and Soret–Dufour effects. Thus, the non-linear partial differential equations of the flow analysis were simplified by using similarity transformation to obtain non-linear coupled equations. The set of simplified equations are solved by using the spectral homotopy analysis method (SHAM) and the spectral relaxation method (SRM). SHAM uses the approach of Chebyshev pseudospectral alongside the homotopy analysis. The SRM uses the concept of Gauss-Seidel techniques to the linear system of equations. Findings Findings revealed that a large value of the non-linear convective parameters for both temperature and concentration increases the velocity profile. A large value of the Williamson term is detected to elevate the velocity plot, whereas the Casson parameter degenerates the velocity profile. The thermal radiation was found to elevate both velocity and temperature as its value increases. The imposed magnetic field was found to slow down the fluid velocity by originating the Lorentz force. Originality/value The novelty of this paper is to explore the heat and mass transfer effects on MHD non-Newtonian fluids flow through an inclined thermally-stratified porous medium. The model is formulated in an inclined plate and embedded in a thermally-stratified porous medium which to the best of the knowledge has not been explored before in literature. Two elegance spectral numerical techniques have been used in solving the modeled equations. Both SRM and SHAM were found to be accurate.

An Analytical Approach to the Heat and Mass Transfer Processes in Counterflow Cooling Towers

2006 ◽  
Vol 128 (11) ◽  
pp. 1142-1148 ◽  
Author(s):  
Chengqin Ren
Keyword(s):  
Mass Transfer ◽  
Differential Equations ◽  
Heat And Mass Transfer ◽  
Analytical Model ◽  
Operating Conditions ◽  
Cooling Towers ◽  
Accurate Analysis ◽  
Transfer Resistance ◽  
Transfer Processes ◽  
Mass Transfer Processes

Quick and accurate analysis of cooling tower performance, outlet conditions of moist air, and parameter profiles along the tower height is very important in rating and design calculations. This paper developed an analytical model for the coupled heat and mass transfer processes in counterflow cooling towers based on operating conditions more realistic than most conventionally adopted Merkel approximations. In modeling, values of the Lewis factor were not necessarily specified as unity. Effects of water loss by evaporation and water film heat transfer resistance were also considered in the model equations. Within a relatively narrow range of operating conditions, the humidity ratio of air in equilibrium with the water surface was assumed to be a linear function of the surface temperature. The differential equations were rearranged and an analytical solution was developed for newly defined parameters. The analytical model predicts the tower performances, outlet conditions, and parameter profiles quickly and accurately when comparing with the numerical integration of the original differential equations.

scholarly journals Analysis of Entropy Production in Structured Chemical Reactors: Optimization for Catalytic Combustion of Air Pollutants

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 1017 ◽  
Author(s):  
Mateusz Korpyś ◽  
Anna Gancarczyk ◽  
Marzena Iwaniszyn ◽  
Katarzyna Sindera ◽  
Przemysław J. Jodłowski ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Entropy Production ◽  
Heat And Mass Transfer ◽  
Chemical Reaction ◽  
Catalytic Combustion ◽  
Packed Bed ◽  
Optimization Criterion ◽  
Rational Solutions ◽  
Short Channel ◽  
Flow Friction

Optimization of structured reactors is not without some difficulties due to highly random economic issues. In this study, an entropic approach to optimization is proposed. The model of entropy production in a structured catalytic reactor is introduced and discussed. Entropy production due to flow friction, heat and mass transfer and chemical reaction is derived and referred to the process yield. The entropic optimization criterion is applied for the case of catalytic combustion of methane. Several variants of catalytic supports are considered including wire gauzes, classic (long-channel) and short-channel monoliths, packed bed and solid foam. The proposed entropic criterion may indicate technically rational solutions of a reactor process that is as close as possible to the equilibrium, taking into account all the process phenomena such as heat and mass transfer, flow friction and chemical reaction.

scholarly journals Heat and mass transfer analysis of unsteady MHD nanofluid flow through a channel with moving porous walls and medium

AIP Advances ◽  
2016 ◽  
Vol 6 (4) ◽  
pp. 045222 ◽  
Author(s):  
Muhammad Zubair Akbar ◽  
Muhammad Ashraf ◽  
Muhammad Farooq Iqbal ◽  
Kashif Ali
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Nanofluid Flow ◽  
Flow Through ◽  
Porous Walls

Design of Microscale Heat and Mass Exchangers for Absorption Space Conditioning Applications

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Ananda Krishna Nagavarapu ◽  
Srinivas Garimella
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Flow Distribution ◽  
Mass Transfer Process ◽  
High Heat ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Pressure Drops ◽  
Transfer Rates ◽  
Small Absorption

This paper presents the development of a miniaturization technology for heat and mass exchangers used in absorption heat pumps. The exchanger consists of an array of parallel, aligned alternating shims with integral microscale features, enclosed between cover plates. These microscale features facilitate the flow of the various fluid streams and the associated heat and mass transfer. In an absorber application, effective vapor and solution contact and microscale features for the flow of both the solution and the coolant induce high heat and mass transfer rates without any active or passive surface enhancement. The geometry ensures even flow distribution with minimal overall pressure drops. A model of the coupled heat and mass transfer process for ammonia-water absorbers using this configuration under typical operating conditions demonstrates the potential for extremely small absorption components. The proposed concept is compact, modular, versatile, and in an eventual implementation, can be mass produced. Additionally, the same concept can be extended to the other absorption heat pump components as well as for several other industries involved in multicomponent fluid processes.

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