On the steady-state behavior of the nonadiabatic autothermal tubular reactor

Lovo, Marianne; Balakotaiah, Vemuri

doi:10.1016/0009-2509(94)00197-9

Cited by 3 publications

(2 citation statements)

References 16 publications

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“…The conventional approach to thermal management of chemical processes is heat transfer with another stream, either removing heat from an exothermic process or adding heat to an endothermic process [35,36]. This management can be accomplished using either indirect heat transfer, in which the streams are physically separated by a wall through which heat is conducted, or direct heat transfer, in which the two streams are physically intermingled but are of distinct phases that can be separated from one another after heat transfer is accomplished [37,38].…”

Section: Resultsmentioning

confidence: 99%

WITHDRAWN: Mechanism of process intensification by microchannel reactors

Chen

2022

Preprint

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The unique advantages of microchannel reactors are enhanced heat transfer due to the large surface area-to-volume ratio, and enhanced mass transfer. The good heat transfer properties allow a precise temperature control of reactions. However, the mechanisms for the effects of design factors on heat transfer characteristics are still not fully understood. This study relates to a thermochemical process for producing hydrogen by the catalytic endothermic reaction of methanol with steam in a thermally integrated microchannel reforming reactor. Computational fluid dynamics simulations are conducted to better understand the consumption, generation, and exchange of thermal energy between endothermic and exothermic processes in the reactor. The effects of wall heat conduction properties on heat transfer characteristics and reactor performance are investigated. The results indicate that the yields and selectivity can be improved by using microchannel process technology at more extreme parameters. Process intensification may be achieved using microchannel process technology where chemical processors are employed that are characterized by parallel arrays of microchannels. Processes are intensified using microchannel process technology by decreasing transfer resistance between process fluids and channel walls. Process intensification allows for use of more active catalysts than conventional processes, greatly increasing the throughput per unit volume. As a result of process intensification, overall system volumes can be reduced by about ten to one hundred-fold or more when compared to conventional hardware.

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Section: Resultsmentioning

confidence: 99%

WITHDRAWN: Mechanism of process intensification by microchannel reactors

Chen

2022

Preprint

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“…The prediction of steady-state multiplicity is intriguing and bears implications for thermally efficient heat-integrated microsystems constructed from thermally insulating materials. Much has been written on the subject of steady-state multiplicity in stirred pots and empty tubes, which has often been attributed to nonlinear kinetics, fluid-phase dispersion, or transport limitations within the catalyst. – It is important to note that for the case of isothermal packaging and sufficient CP and NTU corresponding to isothermal coolant and solid-phase conditions the system of equations reduces to a single plug-flow reacting fluid described by an initial-value ordinary differential equation which must yield a unique solution . The introduction of boundary-value equations describing the solid-phase temperature as well as any countercurrent flows in turn allows the possibility of multiple steady states .…”

Section: Resultsmentioning

confidence: 99%

Parametric Study of Solid-Phase Axial Heat Conduction in Thermally Integrated Microchannel Networks

Moreno

Murphy

Wilhite

2008

Ind. Eng. Chem. Res.

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A parametric study is presented to highlight design challenges of thermally integrated microchannel networks for portable chemistry and/or fuels reforming. One-dimensional modeling analysis of heat transfer in a twofluid system is presented for the case of (i) two nonreacting fluids (heat exchanger), (ii) a single exothermic reacting fluid and a second nonreacting fluid (regenerative combustor), and (iii) one exothermic reacting fluid and a second endothermic reacting fluid (heat exchanger reactor). In each case, the influence of solid-phase thermal conductivity and thermal packaging upon thermal efficiency, reaction conversion, and steady-state multiplicity is investigated. Results demonstrate the importance of both packaging and solid-phase axial thermal conduction upon system performance, with optimal performance obtained using low thermal conductivity substrates. Modeling analysis predicts steady-state multiplicity when employing low thermal conductivity materials, illustrating the need for future detailed stability analysis. Lastly, simplified mechanical analysis is presented to illustrate the value of coupled thermomechanical analysis.

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