The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Michel Cabassud - One of the best experts on this subject based on the ideXlab platform.
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A Comparison Study of Nonlinear State Observer Design: Application to an Intensified Heat-Exchanger/Reactor
2020Co-Authors: Xue Han, Michel Cabassud, Boutaib DahhouAbstract:In this paper, five classical nonlinear state observers: extended Luenberger observer (ELO), extended Kalman filter (EKF), high-gain observer (HGO), sliding mode observer (SMO) and adaptive observer (AO), are applied to an intensified chemical Heat Exchanger/Reactor (HEX Reactor). In order to choose a suitable observer to develop a new fault diagnosis algorithm for this high nonlinear system, the behaviors of these observers are compared. The maximum overshoot and the settling time, which are the key features of the dynamic of the output estimation error system, are used as the criteria to compare the performances of the observers. Both cases with and without measurement noise are considered. It is concluded that the AO presents the fastest convergence speed and the minimum oscillation for the application to the HEX Reactor. And the information provided by the AO will be further used for its fault diagnosis.
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The Fault Tolerant Control Design of an Intensified Heat-Exchanger/Reactor Using a Two-Layer, Multiple-Model Structure.
Sensors (Basel Switzerland), 2020Co-Authors: Boutaib Dahhou, Michel CabassudAbstract:The Heat-Exchanger/Reactor (HEX Reactor) is a kind of plug-flow chemical Reactor which combines high Heat transfer ability with good chemical performances. It was designed under the popular trend of process intensification in chemical engineering. Previous studies have investigated its characteristics and developed its nominal model. This paper is concerned with its fault tolerant control (FTC) applications. To avoid the difficulties and nonlinearities of this HEX Reactor under chemical reactions, a two-layer, multiple-model structure is proposed for designing the FTC scheme. The first layer focuses on representing the nonlinear system with a bank of local linear models while the second layer uses model banks for approaching faulty situations. Model banks are achieved by system identification, and the corresponding controller banks are designed using model predictive control (MPC). The unscented Kalman filter (UKF) is introduced to estimate the states and form the fault detection and isolation (FDI) section. Finally, the FTC simulation and validation results are presented. The idea of a two-layer, multiple-model structure presents a general framework for FTC design of complex and highly nonlinear systems, such as the HEX Reactor, whose mathematical model has been created. It implements the design process in an unusual way and is also worth trying on other cases.
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MED - A Comparison Study of Nonlinear State Observer Design: Application to an Intensified Heat-Exchanger/Reactor
2020 28th Mediterranean Conference on Control and Automation (MED), 2020Co-Authors: Xue Han, Michel Cabassud, Boutaib DahhouAbstract:In this paper, five classical nonlinear state observers: extended Luenberger observer (ELO), extended Kalman filter (EKF), high-gain observer (HGO), sliding mode observer (SMO) and adaptive observer (AO), are applied to an intensified chemical Heat Exchanger/Reactor (HEX Reactor). In order to choose a suitable observer to develop a new fault diagnosis algorithm for this high nonlinear system, the behaviors of these observers are compared. The maximum overshoot and the settling time, which are the key features of the dynamic of the output estimation error system, are used as the criteria to compare the performances of the observers. Both cases with and without measurement noise are considered. It is concluded that the AO presents the fastest convergence speed and the minimum oscillation for the application to the HEX Reactor. And the information provided by the AO will be further used for its fault diagnosis.
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Nonlinear Observer Based Fault Diagnosis for an Innovative Intensified Heat-Exchanger/Reactor
Proceedings of the 11th International Conference on Modelling Identification and Control (ICMIC2019), 2019Co-Authors: Xue Han, Boutaib Dahhou, Michel CabassudAbstract:This paper describes an application of a fault detection and isolation (FDI) scheme for an intensified Heat-Exchanger (HEX)/Reactor, where the exothermic chemical reaction of sodium thiosulfate oxidation by hydrogen peroxide is performed. To achieve this, precise estimation of all states of HEX/Reactor, including temperatures and concentrations of different reactants, as well as process fault detection and isolation is completed by a high gain observer. Then, process fault identification is achieved by several banks of interval filters. Finally, an intensified HEX/Reactor is used to validate the effectiveness of the proposed strategy. Simulation results are shown to illustrate the performance of the algorithm presented.
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development of a numerical model for a compact intensified Heat Exchanger Reactor
Processes, 2019Co-Authors: Xue Han, Michel Cabassud, Boutaib DahhouAbstract:A Heat-Exchanger/Reactor (HEX Reactor) is a kind of plug-flow chemical Reactor which combines high Heat transfer ability and chemical performance. It is a compact Reactor designed under the popular trend of process intensification in chemical engineering. Previous studies have investigated its characteristics experimentally. This paper aimed to develop a general numerical model of the HEX Reactor for further control and diagnostic use. To achieve this, physical structure and hydrodynamic and thermal performance were studied. A typical exothermic reaction, which was used in experiments, is modeled in detail. Some of the experimental data without reaction were used for estimating the Heat transfer coefficient by genetic algorithm. Finally, a non-linear numerical model of 255 calculating modules was developed on the Matlab/Simulink platform. Simulations of this model were done under conditions with and without chemical reactions. Results were compared with reserved experimental data to show its validity and accuracy. Thus, further research such as fault diagnosis and fault-tolerant control of this HEX Reactor could be carried out based on this model. The modeling methodology specified in this paper is not restricted, and could also be used for other reactions and other sizes of HEX Reactors.
Christian Sattler - One of the best experts on this subject based on the ideXlab platform.
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Solar thermochemical Heat storage via the Co3O4/CoO looping cycle: Storage Reactor modelling and experimental validation
Solar Energy, 2017Co-Authors: Abhishek Singh, Gunnar Lantin, Simone Tescari, Christos Agrafiotis, Martin Roeb, Christian SattlerAbstract:Abstract Thermochemical energy storage (TCES) systems utilize reversible reactions to store solar energy in chemical form. The present work focuses on the cobalt/cobaltous oxide (Co3O4/CoO pair) based redox cycle in which the active oxide is coated on a cordierite honeycomb structure. During the redox cycle, cobalt oxide uptakes and releases oxygen from/to an air stream coming in direct contact with it. Thus air acts as a reaction medium as well as a Heat transfer fluid (HTF). In this configuration, the storage material works as a Heat storage medium and also a Heat Exchanger. A two-dimensional, axisymmetric numerical model to simulate the Heat and mass transfer and the chemical reaction in the thermochemical Heat storage Reactor has been developed. Experimental results from a 74 kW hth-capacity prototype Reactor installed at the Solar Tower Julich test facility, Germany, were used to validate the numerical model. The time-dependent boundary conditions in the form of inlet temperature and inlet mass flow rate from the experiments were employed in the numerical model. The temperatures of the redox material at different locations inside the prototype thermochemical storage/Heat Exchanger Reactor were used for the numerical model validation. Total energy stored/released (sensible as well as chemical) during the experiments was also compared with the numerical model results. From this study, it is concluded that the numerical model can accurately predict charging/discharging processes for the cobalt oxide based thermochemical storage Reactor system for multiple redox looping cycles. The model allows a better understanding of the complete process and helps to identify the effect of variation of boundary conditions on the system.
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solar thermochemical Heat storage via the co3o4 coo looping cycle storage Reactor modelling and experimental validation
Solar Energy, 2017Co-Authors: Abhishek Singh, Gunnar Lantin, Simone Tescari, Christos Agrafiotis, Martin Roeb, Christian SattlerAbstract:Abstract Thermochemical energy storage (TCES) systems utilize reversible reactions to store solar energy in chemical form. The present work focuses on the cobalt/cobaltous oxide (Co3O4/CoO pair) based redox cycle in which the active oxide is coated on a cordierite honeycomb structure. During the redox cycle, cobalt oxide uptakes and releases oxygen from/to an air stream coming in direct contact with it. Thus air acts as a reaction medium as well as a Heat transfer fluid (HTF). In this configuration, the storage material works as a Heat storage medium and also a Heat Exchanger. A two-dimensional, axisymmetric numerical model to simulate the Heat and mass transfer and the chemical reaction in the thermochemical Heat storage Reactor has been developed. Experimental results from a 74 kW hth-capacity prototype Reactor installed at the Solar Tower Julich test facility, Germany, were used to validate the numerical model. The time-dependent boundary conditions in the form of inlet temperature and inlet mass flow rate from the experiments were employed in the numerical model. The temperatures of the redox material at different locations inside the prototype thermochemical storage/Heat Exchanger Reactor were used for the numerical model validation. Total energy stored/released (sensible as well as chemical) during the experiments was also compared with the numerical model results. From this study, it is concluded that the numerical model can accurately predict charging/discharging processes for the cobalt oxide based thermochemical storage Reactor system for multiple redox looping cycles. The model allows a better understanding of the complete process and helps to identify the effect of variation of boundary conditions on the system.
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Numerical modeling and experimental validation of a solar thermochemical energy storage Reactor
2016Co-Authors: Abhishek Singh, Gunnar Lantin, Simone Tescari, Christos Agrafiotis, Martin Roeb, Matthias Lange, Christian SattlerAbstract:Thermochemical energy storage (TCES) systems utilize reversible reactions to store solar energy in chemical form. Several reversible systems such as oxides carbonation/decarbonation, ammonia-based cycle, hydroxide systems, organic and redox cycles are currently under study. In the aforementioned systems, reactive materials are mainly in the form of fluid or powders. The present work focuses on the cobalt oxide (Co3O4/CoO pair) based redox cycle in which cobalt oxide is coated on a cordierite honeycomb structure. During the redox cycle, cobalt oxide uptakes and releases oxygen from/to an air stream coming in direct contact with it. Thus air acts as a reaction medium as well as a Heat transfer fluid (HTF). In this configuration, the storage material works as a Heat storage medium and also a Heat Exchanger. A two-dimensional, axisymmetric numerical model to simulate the Heat and mass transfer and the chemical reaction in the thermochemical Heat storage Reactor has been developed. Experimental results from a 74 kWhth-capacity prototype Reactor installed at the test facility of Solar Tower Julich, Germany, were used to validate the numerical model. The time-dependent boundary conditions in the form of inlet temperature and inlet mass flow rate from the experiments were employed in the numerical model. The temperatures of the redox material at different locations inside the prototype thermochemical storage/Heat Exchanger Reactor were used for the numerical model validation. Total energy stored (sensible as well as chemical) during the experiments was also compared with the numerical model results. From this study, it is concluded that the numerical model can accurately predict charging/discharging processes for the cobalt oxide based thermochemical storage Reactor system for multiple redox looping cycles. The model allows a better understanding of the complete process and helps to understand the effect of variation of boundary conditions on the system.
Patrice Tochon - One of the best experts on this subject based on the ideXlab platform.
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Implementation of ‘chaotic’ advection for viscous fluids in Heat Exchanger/Reactors
Chemical Engineering and Processing: Process Intensification, 2017Co-Authors: Zoé Anxionnaz-minvielle, Félicie Theron, Michel Cabassud, Patrice Tochon, Raphael Couturier, Clément Magallon, Christophe GourdonAbstract:When viscous fluids are involved, laminar hydraulic conditions and Heat and mass transfer intensification are conflicting phenomena. A channel geometry based on Split-And-Recombine (SAR) patterns is experimentally investigated. The principle implements the Baker’s transformation and ‘chaotic’ structures are generated to promote Heat and mass transfer. This work assesses the energy efficiency of different Heat Exchanger/Reactors integrating these SAR patterns. The Heat transfer capacity is assessed and compared with the energy consumption of each mock-up. It is sensitive to the cooling mode and to the number of SAR patterns per length unit as well. The continuous oxidation of sodium thiosulfate with hydrogen peroxide has been implemented. Conversions up to 99% are reached according to the utility fluid temperature and the residence time. Finally, the whole performances of the SAR geometries are compared to a plate-type Heat Exchanger/Reactor with a corrugated pattern. The more viscous the fluid, the more the energy efficiency of the SAR design increases compared to the corrugated design because of the balance between advection and diffusion mechanisms. The interest in terms of energy efficiency in working with SAR Heat Exchanger/Reactor appears from Reynolds numbers below 50.
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Characterization of the performances of an innovative Heat-Exchanger/Reactor
Chemical Engineering and Processing: Process Intensification, 2015Co-Authors: Félicie Theron, Zoé Anxionnaz-minvielle, Michel Cabassud, Christophe Gourdon, Patrice TochonAbstract:The use of Heat Exchanger/Reactors (HEX/Reactors) is a promising way to overcome the barrier of poor Heat transfer in batch Reactors. However to reach residence time long enough to complete the chemistry,low Reynolds number has to be combined with both a plug flow behaviour and the intensification of Heat and mass transfers. This work concerns the experimental approach used to characterize an innovative HEX/Reactor. The pilot is made of three process plates sandwiched between five utility plates. The process stream flows in a 2 mm corrugated channel. Pressure drop and residence time distribution characterizations aim at studying the flow hydrodynamics. Identified Darcy correlations point out the transition between laminar and turbulent flow around a Reynolds number equal to 200. Moreover the flow behaves like a quasi-plug flow (Pe > 185). The Heat transfer and mixing time have also been investigated. The ratio between the reaction kinetics and the mixing time is over 100 and the intensification factor ranges from5000 to 8000 kW m−3K−1. As a consequence, no limitations were identified which allows the implementation of an exothermic reaction. It has been successfully performed under severe temperature and concentration conditions, batchwise unreachable. Thus, it highlights the interest of using this continuous HEX/Reactor.
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Influence of the meandering channel geometry on the thermo-hydraulic performances of an intensified HeatExchanger/Reactor
Chemical Engineering and Processing: Process Intensification, 2015Co-Authors: Zoé Anxionnaz-minvielle, Michel Cabassud, Christophe Gourdon, Patrice TochonAbstract:In the global context of process intensification, Heat Exchanger/Reactors are promising apparatuses to implement exothermic chemical syntheses. However, unlike Heat exchange processes, the implementation of chemical syntheses requires to control the residence time to complete the chemistry. A way to combine the laminar regime (i.e. enough residence time) with a plug flow and the intensification of both Heat and mass transfers is the corrugation of the reaction path. In this work, the experimental set-up is based on plate Heat Exchanger/Reactor technology. 7 milli channel corrugated geometries varying the corrugation angle, the curvature radius, the developed length, the hydraulic diameter and the aspect ratio have been designed and experimentally characterized (Heat transfer, mixing times, pressure drops, RTD). The objectives were to assess their respective performances to derive some correlations depending on the channel design. The results confirmed the benefits of the reaction channel corrugation. Heat and mass transfers have been intensified while maintaining a plug flow behavior in the usually laminar flow regime. Moreover, whatever the meandering channel's curvature radius, the results highlighted the relevance of considering the Dean number as the scale-up parameter. This dimension less number, more than the Reynolds number, seems to govern the flow in the wavy channels.
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characterization of the performances of an innovative Heat Exchanger Reactor
Chemical Engineering and Processing, 2014Co-Authors: Félicie Theron, Michel Cabassud, Christophe Gourdon, Zoe Anxionnazminvielle, Patrice TochonAbstract:The use of Heat Exchanger/Reactors (HEX/Reactors) is a promising way to overcome the barrier of poor Heat transfer in batch Reactors. However to reach residence time long enough to complete the chemistry,low Reynolds number has to be combined with both a plug flow behaviour and the intensification of Heat and mass transfers. This work concerns the experimental approach used to characterize an innovative HEX/Reactor. The pilot is made of three process plates sandwiched between five utility plates. The process stream flows in a 2 mm corrugated channel. Pressure drop and residence time distribution characterizations aim at studying the flow hydrodynamics. Identified Darcy correlations point out the transition between laminar and turbulent flow around a Reynolds number equal to 200. Moreover the flow behaves like a quasi-plug flow (Pe > 185). The Heat transfer and mixing time have also been investigated. The ratio between the reaction kinetics and the mixing time is over 100 and the intensification factor ranges from5000 to 8000 kW m−3K−1. As a consequence, no limitations were identified which allows the implementation of an exothermic reaction. It has been successfully performed under severe temperature and concentration conditions, batchwise unreachable. Thus, it highlights the interest of using this continuous HEX/Reactor.
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influence of the meandering channel geometry on the thermo hydraulic performances of an intensified Heat Exchanger Reactor
Chemical Engineering and Processing, 2013Co-Authors: Zoe Anxionnazminvielle, Michel Cabassud, Christophe Gourdon, Patrice TochonAbstract:Abstract In the global context of process intensification, Heat Exchanger/Reactors are promising apparatuses to implement exothermic chemical syntheses. However, unlike Heat exchange processes, the implementation of chemical syntheses requires to control the residence time to complete the chemistry. A way to combine the laminar regime (i.e. enough residence time) with a plug flow and the intensification of both Heat and mass transfers is the corrugation of the reaction path. In this work, the experimental set-up is based on plate Heat Exchanger/Reactor technology. 7 milli-channel corrugated geometries varying the corrugation angle, the curvature radius, the developed length, the hydraulic diameter and the aspect ratio have been designed and experimentally characterized (Heat transfer, mixing times, pressure drops, RTD). The objectives were to assess their respective performances to derive some correlations depending on the channel design. The results confirmed the benefits of the reaction channel corrugation. Heat and mass transfers have been intensified while maintaining a plug flow behaviour in the usually laminar flow regime. Moreover, whatever the meandering channel's curvature radius, the results highlighted the relevance of considering the Dean number as the scale-up parameter. This dimensionless number, more than the Reynolds number, seems to govern the flow in the wavy channels.
Mohammad Reza Rahimpour - One of the best experts on this subject based on the ideXlab platform.
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Investigation of thermally double coupled double membrane Heat Exchanger Reactor to produce dimethyl ether and methyl formate
Journal of Natural Gas Science and Engineering, 2016Co-Authors: Ali Bakhtyari, Reza Haghbakhsh, Mohammad Reza RahimpourAbstract:Abstract Owing to concerns associated with energy consumption and energy intensive methods in the chemical industries, the present study aims to investigate production of some downstream products of natural gas in a recuperative configuration. Accordingly, simultaneous production of dimethyl ether from methanol and syngas and also methyl formate from methanol is investigated in a catalytic Heat-Exchanger Reactor assisted with water perm-selective membranes. Dimethyl ether synthesis from methanol and syngas are exothermic reactions supplying required energy for the methanol dehydrogenation reaction. Produced waters in both exothermic sides are eliminated from reaction media by permeation through the perm-selective membranes equipped on the inner and outer surfaces of the Reactor. A feasibility study is implemented through a mathematical model based on mass and energy balance. Genetic algorithm as a powerful method in nonlinear optimization problems is applied to obtain optimum operating conditions. 97% methanol conversion to dimethyl ether, 66% methanol conversion to methyl formate and 17% hydrogen conversion are the advancements of the proposed thermally double-coupled double-membrane Reactor working under optimum conditions.
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Optimal conditions in converting methanol to dimethyl ether, methyl formate, and hydrogen utilizing a double membrane Heat Exchanger Reactor
Journal of Natural Gas Science and Engineering, 2016Co-Authors: Ali Bakhtyari, Mahboubeh Parhoudeh, Mohammad Reza RahimpourAbstract:Abstract Following importance of investigating new sources of energy with highly efficient processes, a new configuration for simultaneous production of high purity dimethyl ether (DME), hydrogen and methyl formate (MF) is numerically studied in this work. In this regard, a catalytic Heat-Exchanger Reactor assisted with two different membranes for methanol conversion and in-situ separation of products is simulated. The interesting feature of this system is utilizing only one feedstock (i.e. methanol) to produce different valuable products. Methanol is dehydrated through an exothermic reaction and supplies required energy for the methanol dehydrogenation reaction. Produced water in the exothermic side and produced hydrogen in the endothermic side are separated by permeation to particular membranes. A steady state one-dimensional plug flow model is developed to evaluate molar and thermal behavior of the system. Optimum operating conditions are determined applying genetic algorithm as a powerful optimization method. The proposed configuration working under optimum conditions promotes methanol conversion to DME to % 95.1 and methanol conversion to MF to % 99.6 providing high purity products in the output streams.
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Sorption enhanced process by integrated Heat-Exchanger Reactor assisted by fluidization concept for methanol synthesis
Chemical Engineering and Processing: Process Intensification, 2016Co-Authors: Bayat, M. Heravi, Mohammad Reza RahimpourAbstract:Abstract Coupling Reactor has been identified as one of the most promising configurations for simultaneous production of methanol and hydrogen; as well stabilizing the atmospheric greenhouse gases level. In this work, methanol synthesis is carried out in exothermic side, which is a fluidized-bed Reactor with in-situ water adsorption and supplies the necessary Heat for the dehydrogenation of cyclohexane in endothermic side. Simulation results show that selective water adsorption from methanol synthesis in Fluidized bed Sorption Enhanced Thermally Coupled Reactor (FSE-TCR) leads to a considerable intensification of methanol production compared to zero solid mass ratio condition. Subsequently, a multi-objective optimization of FSE-TCR is conducted using the NSGA-II algorithm, and Pareto optimal frontiers are obtained in two cases including the maximum methanol production rate and selectivity. The Shannon’s Entropy, LINMAP, and TOPSIS methods as three decision making approaches are used to select the final solution of Pareto front. The optimization results enhance about 214.3 and 280.5 ton day −1 methanol production rate and CO 2 removal rate, respectively, based TOPSIS methods in comparison with the conventional methanol configuration. Furthermore, the optimization results represent 6.88 ton day −1 enhancement in hydrogen production rate in comparison with the non-optimized configuration using the same catalyst loading and duty.
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a comparative study of two different configurations for exothermic endothermic Heat Exchanger Reactor
Chemical Engineering and Processing, 2012Co-Authors: M. Bayat, Mohammad Reza Rahimpour, M. Taheri, M. Pashaei, S. SharifzadehAbstract:Abstract The coupling of the energy intensive endothermic reaction systems with appropriate exothermic reactions reduces the size of the Reactors and can improve the thermal efficiency of processes. One type of a suitable Reactor for such a kind of coupling is the Heat Exchanger Reactor. In this study, the catalytic methanol synthesis is coupled with the catalytic dehydrogenation of cyclohexane to benzene in an integrated Reactor formed from two fixed beds separated by a wall where Heat is transferred across the surface of the tube. A steady-state heterogeneous model of the two fixed beds predicts the performance of the two different configurations of the thermally coupled Reactor. The co-current mode is investigated and the simulation results are compared with the corresponding predictions for the industrial methanol fixed bed Reactor operating in the same feed conditions. The results of the study reveal that should the exothermic and endothermic reactions be located in the shell side and tube side, respectively, the methanol production rate will increase in comparison with the conventional methanol synthesis Reactor as well as the case where the exothermic reaction is located in the tube side and endothermic reaction in the shell side.
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A comparative study of two different configurations for exothermic–endothermic Heat Exchanger Reactor
Chemical Engineering and Processing: Process Intensification, 2012Co-Authors: M. Bayat, Mohammad Reza Rahimpour, M. Taheri, M. Pashaei, S. SharifzadehAbstract:Abstract The coupling of the energy intensive endothermic reaction systems with appropriate exothermic reactions reduces the size of the Reactors and can improve the thermal efficiency of processes. One type of a suitable Reactor for such a kind of coupling is the Heat Exchanger Reactor. In this study, the catalytic methanol synthesis is coupled with the catalytic dehydrogenation of cyclohexane to benzene in an integrated Reactor formed from two fixed beds separated by a wall where Heat is transferred across the surface of the tube. A steady-state heterogeneous model of the two fixed beds predicts the performance of the two different configurations of the thermally coupled Reactor. The co-current mode is investigated and the simulation results are compared with the corresponding predictions for the industrial methanol fixed bed Reactor operating in the same feed conditions. The results of the study reveal that should the exothermic and endothermic reactions be located in the shell side and tube side, respectively, the methanol production rate will increase in comparison with the conventional methanol synthesis Reactor as well as the case where the exothermic reaction is located in the tube side and endothermic reaction in the shell side.
Christophe Gourdon - One of the best experts on this subject based on the ideXlab platform.
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Implementation of ‘chaotic’ advection for viscous fluids in Heat Exchanger/Reactors
Chemical Engineering and Processing: Process Intensification, 2017Co-Authors: Zoé Anxionnaz-minvielle, Félicie Theron, Michel Cabassud, Patrice Tochon, Raphael Couturier, Clément Magallon, Christophe GourdonAbstract:When viscous fluids are involved, laminar hydraulic conditions and Heat and mass transfer intensification are conflicting phenomena. A channel geometry based on Split-And-Recombine (SAR) patterns is experimentally investigated. The principle implements the Baker’s transformation and ‘chaotic’ structures are generated to promote Heat and mass transfer. This work assesses the energy efficiency of different Heat Exchanger/Reactors integrating these SAR patterns. The Heat transfer capacity is assessed and compared with the energy consumption of each mock-up. It is sensitive to the cooling mode and to the number of SAR patterns per length unit as well. The continuous oxidation of sodium thiosulfate with hydrogen peroxide has been implemented. Conversions up to 99% are reached according to the utility fluid temperature and the residence time. Finally, the whole performances of the SAR geometries are compared to a plate-type Heat Exchanger/Reactor with a corrugated pattern. The more viscous the fluid, the more the energy efficiency of the SAR design increases compared to the corrugated design because of the balance between advection and diffusion mechanisms. The interest in terms of energy efficiency in working with SAR Heat Exchanger/Reactor appears from Reynolds numbers below 50.
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Characterization of the performances of an innovative Heat-Exchanger/Reactor
Chemical Engineering and Processing: Process Intensification, 2015Co-Authors: Félicie Theron, Zoé Anxionnaz-minvielle, Michel Cabassud, Christophe Gourdon, Patrice TochonAbstract:The use of Heat Exchanger/Reactors (HEX/Reactors) is a promising way to overcome the barrier of poor Heat transfer in batch Reactors. However to reach residence time long enough to complete the chemistry,low Reynolds number has to be combined with both a plug flow behaviour and the intensification of Heat and mass transfers. This work concerns the experimental approach used to characterize an innovative HEX/Reactor. The pilot is made of three process plates sandwiched between five utility plates. The process stream flows in a 2 mm corrugated channel. Pressure drop and residence time distribution characterizations aim at studying the flow hydrodynamics. Identified Darcy correlations point out the transition between laminar and turbulent flow around a Reynolds number equal to 200. Moreover the flow behaves like a quasi-plug flow (Pe > 185). The Heat transfer and mixing time have also been investigated. The ratio between the reaction kinetics and the mixing time is over 100 and the intensification factor ranges from5000 to 8000 kW m−3K−1. As a consequence, no limitations were identified which allows the implementation of an exothermic reaction. It has been successfully performed under severe temperature and concentration conditions, batchwise unreachable. Thus, it highlights the interest of using this continuous HEX/Reactor.
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Influence of the meandering channel geometry on the thermo-hydraulic performances of an intensified HeatExchanger/Reactor
Chemical Engineering and Processing: Process Intensification, 2015Co-Authors: Zoé Anxionnaz-minvielle, Michel Cabassud, Christophe Gourdon, Patrice TochonAbstract:In the global context of process intensification, Heat Exchanger/Reactors are promising apparatuses to implement exothermic chemical syntheses. However, unlike Heat exchange processes, the implementation of chemical syntheses requires to control the residence time to complete the chemistry. A way to combine the laminar regime (i.e. enough residence time) with a plug flow and the intensification of both Heat and mass transfers is the corrugation of the reaction path. In this work, the experimental set-up is based on plate Heat Exchanger/Reactor technology. 7 milli channel corrugated geometries varying the corrugation angle, the curvature radius, the developed length, the hydraulic diameter and the aspect ratio have been designed and experimentally characterized (Heat transfer, mixing times, pressure drops, RTD). The objectives were to assess their respective performances to derive some correlations depending on the channel design. The results confirmed the benefits of the reaction channel corrugation. Heat and mass transfers have been intensified while maintaining a plug flow behavior in the usually laminar flow regime. Moreover, whatever the meandering channel's curvature radius, the results highlighted the relevance of considering the Dean number as the scale-up parameter. This dimension less number, more than the Reynolds number, seems to govern the flow in the wavy channels.
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Safety enhancement by transposition of the nitration of toluene from semi-batch Reactor to continuous intensified Heat Exchanger Reactor
Chemical Engineering Research and Design, 2015Co-Authors: N. Di Miceli Raimondi, Nelly Olivier-maget, Nadine Gabas, Michel Cabassud, Christophe GourdonAbstract:The behaviour of a continuous intensified Heat Exchanger (HEX) Reactor in case of process failure is analysed and compared to the behaviour of a semi-continuous Reactor. The nitration of toluene is considered as test reaction to identify the main failure scenarios that can lead to thermal runaway in both processes using the HAZOP method.No flow rate of process fluid and utility fluid in the continuous process. No stirring during feeding of the Reactor followed by normal stirring for the semi-continuous Reactor. These scenarios are simulated for both processes and the temperature profiles are observed. This study shows that the temperature is better controlled in the continuous process because of the intrinsic characteristics of the HEX Reactor. In fact, this device has a low reactive volume relative to the mass of the Reactor, allowing a good dissipation of the Heat produced by the reaction, even in case of failure. This characteristic of the intensified Reactor is confirmed by an experimental work.
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characterization of the performances of an innovative Heat Exchanger Reactor
Chemical Engineering and Processing, 2014Co-Authors: Félicie Theron, Michel Cabassud, Christophe Gourdon, Zoe Anxionnazminvielle, Patrice TochonAbstract:The use of Heat Exchanger/Reactors (HEX/Reactors) is a promising way to overcome the barrier of poor Heat transfer in batch Reactors. However to reach residence time long enough to complete the chemistry,low Reynolds number has to be combined with both a plug flow behaviour and the intensification of Heat and mass transfers. This work concerns the experimental approach used to characterize an innovative HEX/Reactor. The pilot is made of three process plates sandwiched between five utility plates. The process stream flows in a 2 mm corrugated channel. Pressure drop and residence time distribution characterizations aim at studying the flow hydrodynamics. Identified Darcy correlations point out the transition between laminar and turbulent flow around a Reynolds number equal to 200. Moreover the flow behaves like a quasi-plug flow (Pe > 185). The Heat transfer and mixing time have also been investigated. The ratio between the reaction kinetics and the mixing time is over 100 and the intensification factor ranges from5000 to 8000 kW m−3K−1. As a consequence, no limitations were identified which allows the implementation of an exothermic reaction. It has been successfully performed under severe temperature and concentration conditions, batchwise unreachable. Thus, it highlights the interest of using this continuous HEX/Reactor.
