Effect of flow configuration on the operation of coupled combustor/reformer microdevices for hydrogen production

Deshmukh, Soumitra; Vlachos, Dionisios G.

doi:10.1016/j.ces.2005.04.082

Cited by 78 publications

(34 citation statements)

References 20 publications

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“…The use of propane instead of methane for combustion is determined by the higher reactivity and stability of propane, as found in our previous work [10]. It has been found that co-current flow configuration at microscales gives better overlap of reaction zones and minimizes hot spots [11,12]. A pseudo-two-dimensional (2D) re-actor model is used; it consists of the continuity equation, the gas-phase energy balance, and the gas and surface species mass balances in the two channels together with the energy balance in the solid wall [13][14][15].…”

Section: Modelingmentioning

confidence: 94%

Millisecond Methane Steam Reforming Via Process and Catalyst Intensification

Stefanidis

Vlachos

2008

Chem Eng & Technol

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The steam reforming of methane on a rhodium/alumina based multifunctional microreactor is simulated using fundamental chemical kinetics in a pseudo-twodimensional microreactor model. The microreactor consists of parallel catalytic plates, whereby catalytic combustion and reforming take place on opposite sides of a wall. Heat exchange happens through the wall. It is shown that reforming can happen in millisecond or lower contact times and proper balancing of flow rates can give high conversions, reasonably high temperatures, and high yield to syngas. It is found that tuning catalyst surface area and internal and external mass and heat transfer through reactor sizing can lead to further process intensification.

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Section: Modelingmentioning

confidence: 94%

Millisecond Methane Steam Reforming Via Process and Catalyst Intensification

Stefanidis

Vlachos

2008

Chem Eng & Technol

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“…However, producing balanced countercurrent designs that match the rates of heat generation in the exothermic channels and heat consumption in the endothermic channels remains an important issue. [11][12][13][14][15] Previous studies 11,13,15 indicate that the coupling of methane steam reforming with methane combustion in a countercurrent flow arrangement is difficult: the reactant depletion occurs in opposite directions relative to the reactor length. This complicates the efficient synchronization of the reaction rates and therefore the rate of heat generation and heat consumption, with the reactor thermal behavior typically drifting to one of two extremes:…”

Section: Introductionmentioning

confidence: 99%

Optimizing the catalyst distribution for countercurrent methane steam reforming in plate reactors

Zanfir¹,

Bâldea²,

Daoutidis

2010

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com).Microscale autothermal reactors remain one of the most promising technologies for efficient hydrogen generation. The typical reactor design alternates microchannels where reforming and catalytic combustion of methane occur, so that exothermic and endothermic reactions take place in close proximity. The influence of flow arrangement on the autothermal coupling of methane steam reforming and methane catalytic combustion in catalytic plate reactors is investigated. The reactor thermal behavior and performance for cocurrent and countercurrent are simulated and compared. A partial overlapping of the catalyst zones in adjacent exothermic and endothermic channels is shown to avoid both severe temperature excursions and reactor extinction. Using an innovative, optimization-based approach for determining the catalyst zone overlap, a solution is provided to the problem of determining the maximum reactor conversion within specified temperature bounds, designed to preserve reactor integrity and operational safety.

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“…The microreactors allow fast heat transfer due to their thin wall thicknesses and thus the reaction is maintained at an optimal operating temperature (Löwe & Ehrfeld, 1999). The energy required for performing an endothermic reaction can be supplied via an exothermic reaction, whose coupling can be achieved by operating endothermic and exothermic reactions in parallel microchannels (Deshmukh & Vlachos, 2005). The model investigated in this study is a membrane microreactor, where a hydrogen-permselective membrane substitutes one of the solid walls of the microchannel.…”

Section: Model Developmentmentioning

confidence: 99%

“…Despite the advantage of room-temperature operation, direct methanol or ethanol systemsoffer only relatively low power density due to methanol/ethanol crossover through the polymer electrolyte membrane and the low reaction rate of fuel oxidation over the anode electrocatalyst. On the other hand, on-board reforming systems generate electric energy in fuel cells from hydrogen by steam reforming, for example, from ethanol (Aicher et al, 2009;Aravamudhan et al, 2005;Deshmukh and Vlachos, 2005;Palo et al, 2002;Sordi et al,2009;Yao et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Parametric study of hydrogen production from ethanol steam reforming in a membrane microreactor

DeSouza

Zanin

Moraes

2013

Braz. J. Chem. Eng.

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-Microreactors are miniaturized chemical reaction systems, which contain reaction channels with characteristic dimensions in the range of 10-500 μm. One possible application for microreactors is the conversion of ethanol to hydrogen used in fuel cells to generate electricity. In this paper a rigorous isothermal, steady-state two-dimensional model was developed to simulate the behavior of a membrane microreactor based on the hydrogen yield from ethanol steam reforming. Furthermore, this membrane microreactor is compared to a membraneless microreactor. A potential advantage of the membrane microreactor is the fact that both ethanol steam reforming and the separation of hydrogen by a permselective membrane occur in one single microdevice. The simulation results for steam reforming yields are in agreement with experimental data found in the literature. The results show that the membrane microreactorpermits a hydrogen yield of up to 0.833 which is more than twice that generated by the membraneless reactor. More than 80% of the generated hydrogen permeates through the membrane and, due to its high selectivity, the membrane microreactor delivers high-purity hydrogen to the fuel cell.

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Effect of flow configuration on the operation of coupled combustor/reformer microdevices for hydrogen production

Cited by 78 publications

References 20 publications

Millisecond Methane Steam Reforming Via Process and Catalyst Intensification

Millisecond Methane Steam Reforming Via Process and Catalyst Intensification

Optimizing the catalyst distribution for countercurrent methane steam reforming in plate reactors

Parametric study of hydrogen production from ethanol steam reforming in a membrane microreactor

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