Hydrodynamics, heat transfer and kinetics reaction of CFD modeling of a batch stirred reactor under hydrothermal carbonization conditions

Sangaré, Diakaridia; Bostyn, Stéphane; Moscosa-Santillán, Mario; Gökalp, İskender

doi:10.1016/j.energy.2020.119635

Cited by 28 publications

(15 citation statements)

References 45 publications

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“…The CFD results are strongly dependent on the mesh quality of the 3D geometry, itself dependent on the number of mesh elements. 42 We increased the number of mesh elements until no significant change in the temperature profile was observed. We retained the temperature profiles obtained with 1776164 mesh elements and swept until 2223038 mesh elements.…”

Section: Resultsmentioning

confidence: 99%

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Modeling Temperature and Species Concentration Profiles on a Continuous-Flow Reactor Applied to Aldol Condensation

et al. 2022

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This paper presents the modeling of a continuous-flow reactor used for the synthesis of organic products. The finite element method software, COMSOL Multiphysics, was used to model transport phenomena and reaction kinetics. The temperature is one of the most important kinetic factors that may modify the reaction. A rise in temperature can generate a positive reaction but also secondary side reactions. The design of our system and of many other continuous systems makes it impossible, however, to measure the temperature throughout the reactor. In this paper, we modeled the temperature profile within the reactors as a function of the flow rate, temperature set point, and type of reactor material. The results demonstrated that although it is not a good thermal conductor, polytetrafluoroethylene can be used like other materials. The desired temperature was not reached for any of the reactor material likely to affect the product yield. The model gave the residence time required to reach the stabilized temperature. The comparison of calculated and experimental values of outlet temperature showed good agreement, with a maximum relative difference of only 5%. Knowledge of the temperature profile made it possible to control the concentration distribution of the chemical species in the reactor. The aldol condensation was chosen to determine the kinetic parameters of this reaction as the products of this reaction are found in many natural molecules and drugs. To integrate the chemical model, the kinetic parameters were determined by using experimental data. An equilibrium concentration of 0.2 mol/L was found with initial reactant concentrations of 0.45 mol/L. The chemical modeling gave the species concentrations throughout the reactor. Calculated concentrations were in good agreement with experimental data, with a maximum relative difference of less than 9%. By modeling this reaction, the reaction yield as a function of reactant concentration, temperature, and residence times was estimated.

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Section: Resultsmentioning

confidence: 99%

“…These profiles are the results of CFD. The CFD results are strongly dependent on the mesh quality of the 3D geometry, itself dependent on the number of mesh elements . We increased the number of mesh elements until no significant change in the temperature profile was observed.…”

Section: Resultsmentioning

confidence: 99%

Modeling Temperature and Species Concentration Profiles on a Continuous-Flow Reactor Applied to Aldol Condensation

et al. 2022

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“…In terms of accounting for heat transfer, particle transport phenomena, and reaction kinetics, it is difficult to develop a computational model able to describe all three components, evident from the absence of such a model. Instead, models are usually created to target the analysis of one of these components to reduce the complexity and the limitations imposed by computational processing time [35]. These constraints directly limit the degree of intricacy; however, with more emphasis on the simulation of thermochemical conversion processes, computational models are showing their increased potential and importance as a tool for this form of technological development [36].…”

Section: General Approach For Current Htc Computational Modelsmentioning

confidence: 99%

“…Sangare et al [35] proposed a computational model also using COMSOL Multiphysics that included a simulation of a stirring component. They solved for both the temperature and velocity fields for the HTC of avocado stone biomass under turbulent flow conditions using the k-ε turbulence flow model.…”

Section: General Approach For Current Htc Computational Modelsmentioning

confidence: 99%

Computational Modeling Approaches of Hydrothermal Carbonization: A Critical Review

2022

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Hydrothermal carbonization (HTC) continues to gain recognition over other valorization techniques for organic and biomass residue in recent research. The hydrochar product of HTC can be effectively produced from various sustainable resources and has been shown to have impressive potential for a wide range of applications. As industries work to adapt the implementation of HTC over large processes, the need for reliable models that can be referred to for predictions and optimization studies are becoming imperative. Although much of the available research relating to HTC has worked on the modeling area, a large gap remains in developing advanced computational models that can better describe the complex mechanisms, heat transfer, and fluid dynamics that take place in the reactor of the process. This review aims to highlight the importance of expanding the research relating to computational modeling for HTC conversion of biomass. It identifies six research areas that are recommended to be further examined for contributing to necessary advancements that need to be made for large-scale and continuous HTC operations. The six areas that are identified for further investigation are variable feedstock compositions, heat of exothermic reactions, type of reactor and scale-up, consideration of pre-pressurization, consideration of the heat-up period, and porosity of feedstock. Addressing these areas in future HTC modeling efforts will greatly help with commercialization of this promising technology.

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“…The model can be further enhanced by direct coupling between the flow, heat transfer modeling, and kinetic routines. Sangare et al (2021) built a 3D CFD model to simulate a batch stirred reactor for HTC of avocado stone. The model was developed by COMSOL Multiphysics 5.2 software.…”

Section: Reactor Modelingmentioning

confidence: 99%

Modeling of thermochemical conversion of waste biomass – a comprehensive review

et al. 2021

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Thermochemical processes, which include pyrolysis, torrefaction, gasification, combustion, and hydrothermal conversions, are perceived to be more efficient in converting waste biomass to energy and value-added products than biochemical processes. From the chemical point of view, thermochemical processes are highly complex and sensitive to numerous physicochemical properties, thus making reactor and process modeling more challenging. Nevertheless, the successful commercialization of these processes is contingent upon optimized reactor and process designs, which can be effectively achieved via modeling and simulation. Models of various scales with numerous simplifying assumptions have been developed for specific applications of thermochemical conversion of waste biomass. However, there is a research gap that needs to be explored to elaborate the scale of applicability, limitations, accuracy, validity, and special features of each model. This review study investigates all above mentioned important aspects and features of the existing models for all established industrial thermochemical conversion processes with emphasis on waste biomass, thus addressing the research gap mentioned above and presenting commercial-scale applicability in terms of reactor designing, process control and optimization, and potential ways to upgrade existing models for higher accuracy.

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Hydrodynamics, heat transfer and kinetics reaction of CFD modeling of a batch stirred reactor under hydrothermal carbonization conditions

Cited by 28 publications

References 45 publications

Modeling Temperature and Species Concentration Profiles on a Continuous-Flow Reactor Applied to Aldol Condensation

Modeling Temperature and Species Concentration Profiles on a Continuous-Flow Reactor Applied to Aldol Condensation

Computational Modeling Approaches of Hydrothermal Carbonization: A Critical Review

Modeling of thermochemical conversion of waste biomass – a comprehensive review

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