A review of microwave-assisted process intensified multiphase reactors

Goyal, Himanshu; Chen, Tai-Ying; Chen, Weiqi; Vlachos, Dionisios G.

doi:10.1016/j.cej.2021.133183

Cited by 77 publications

(27 citation statements)

References 121 publications

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“…have been discussed. Vlachos and coworkers 55 reviewed very recently the advantages and possibilities offered by MW-heating for multiphase reactors. The use of MW in combination with heterogeneous catalysts was also recently reviewed by Palma et al 56 They also discussed the mechanistic effects and energy losses, as well as the problems associated with scale-up.…”

Section: Electrification Of the Chemical Processes And Reactorsmentioning

confidence: 99%

Status and gaps toward fossil-free sustainable chemical production

Centi

Perathoner

2022

Green Chem.

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Section: Electrification Of the Chemical Processes And Reactorsmentioning

confidence: 99%

Status and gaps toward fossil-free sustainable chemical production

Centi

Perathoner

2022

Green Chem.

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“…However, it remains elusive because the measurements of spatiotemporal temperature evolution within microwave-heated reactors remain challenging . Thermocouples are unsuitable for measuring the temperature in microwave cavities, and the commonly employed fiber optics are limited by a maximum temperature of ∼300 °C. , In this regard, computational models that can probe a vast design space to achieve an optimal temperature profile are desirable. However, such models are currently unavailable.…”

Section: Introductionmentioning

confidence: 99%

A Computationally Fast Method to Simulate Microwave-Heated Monoliths

Parmar

Kavale

Goyal

2023

Ind. Eng. Chem. Res.

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Microwave-assisted process intensification is a promising technique hindered by the unavailability of design rules for optimization and scale-up. High-throughput computational models allowing the exploration of a vast design space are imperative for the rapid development and deployment of intensified microwave reactors. Recently, structured reactors, especially monoliths, are emerging as a canonical multiphase reactor setup in the microwave-heating community. The vast separation of scales in these reactors leads to a large number of mesh elements, making the simulations time-consuming and challenging to converge. To this end, we employ volume and asymptotic averaging to represent monoliths, a multiphase system consisting of a fluid and a solid phase, as a continuum or effective medium. We rigorously verify the adequacy of the averaging techniques to predict the spatiotemporal distribution of the electric field, electromagnetic power dissipation, and temperature against fully resolved monolith simulations. The developed continuum model can replicate the three-dimensional transient behavior obtained from the multiphase simulations with an order of magnitude lower computational expense. Moreover, the continuum model allows easier mesh generation and convergence of numerical solution than the multiphase model. The developed multiscale framework can be used to simulate microwave-heated monoliths and other multiphase reactors, such as packed beds and open-cell foams.

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“…Electromagnetic energy generated from renewable sources is an emerging route toward process intensification, electrification, and decarbonization of chemical manufacturing. − Electromagnetic radiation, such as microwaves (MWs), can heat rapidly, volumetrically, and selectively to overcome the heat transfer limitations of conventional processes. − Multiphase systems, especially those with disparate dielectric permittivity, are uniquely impacted by selective MW heating and can sustain distinct phase temperatures. − This effect can yield energy savings, enhanced separation efficiency, and higher reaction selectivity. − MW heating is applied to many separations, such as drying, extraction, and distillation. − These separations are mostly gas–liquid or solid–liquid systems. For instance, MW heating is widely used to extract antioxidants from vegetables, wastes, and plants. − MWs provide a higher recovery rate than conventional solvent extraction .…”

Section: Introductionmentioning

confidence: 99%

Microwave Heating-Induced Temperature Gradients in Liquid–Liquid Biphasic Systems

Chen

Baker-Fales

Goyal

et al. 2022

Ind. Eng. Chem. Res.

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Microwaves (MWs) can enable the electrification and intensification of chemical manufacturing. They have been applied to various unit separations, such as drying, distillation, and extraction, entailing gas–liquid and solid–liquid systems. However, a limited quantitative understanding of MW-heated liquid–liquid biphasic systems related to extraction exists. This work measures the temporal and spatial temperature difference between an aqueous and an organic phase in batch and continuous microfluidic modes. We demonstrate permanent temperature differences between phases over 35 °C and spatiotemporal periodic and quasiperiodic oscillations modulated by the flow patterns. The temperature differences are primarily driven by the faster absorption rate of MW irradiation by the aqueous phase versus the slower heat transfer from the aqueous phase to the organic phase. These are amplified by low specific interfacial area and modifications of the electromagnetic field. We employ a multiphysics model to predict the temperature difference in a batch system. The model is in good agreement with the experiments. We demonstrate a strong effect of input power, dielectric properties of organic solvents, the volume of solvents, and the volume ratio between phases on the temperature difference. A simple analytical model describes the temperature difference and provides design principles. The combined approach offers new insights into the design and optimization of the MW-heated biphasic systems.

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A review of microwave-assisted process intensified multiphase reactors

Cited by 77 publications

References 121 publications

Status and gaps toward fossil-free sustainable chemical production

Status and gaps toward fossil-free sustainable chemical production

A Computationally Fast Method to Simulate Microwave-Heated Monoliths

Microwave Heating-Induced Temperature Gradients in Liquid–Liquid Biphasic Systems

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