International Journal of Thermodynamics, Dec 1, 2013
ABSTRACT This work investigates the ideal performances that could be achieved in the coupling of ... more ABSTRACT This work investigates the ideal performances that could be achieved in the coupling of a Fluidized Bed Combustor with a Stirling engine by placing the head of a Stirling engine, more specifically the elements of the hot side heat exchanger, in direct contact with the sand of the Fluidized Bed Combustor. This choice is primarily suggested by the heat exchange coefficients between the multiphase fluidized bed medium and the surface of the heat exchanger, much larger than those attained when the heat exchanger is located in the stream of hot flue gases. Moreover, the mechanical action exerted by the fluidized solid particles substantially reduces the fouling usually caused by impurities in exhaust gases of a biomass combustion process. A mathematical model, which covers a small size fluidized bed and the Stirling engine, is developed and used to optimize design and operating conditions with specific attention to the Stirling hot side heat exchanger. It is shown that the choice to place the heat exchanger in direct contact with the fluidized bed can lead to an improvement of performance in terms of efficiency and shaft power output, making the development of this kind of system attractive for the production of energy from renewable sources.
Abstract The structure of a catalytic reactor integrating two reactions is yield-optimized in ter... more Abstract The structure of a catalytic reactor integrating two reactions is yield-optimized in terms of distribution of active sites of two catalysts in a hybrid pellet, using a two-scale (pellet and reactor) approach. POD-Galerkin model reduction is adopted to reduce the burden of the optimization algorithm. Results show that optimal structuring can have a key role in catalyst process intensification, in terms of yield, chosen as the performance indicator and thus also as the objective function for the optimization problem.
A fast development over the last decades of the optical setups has made available measurements of... more A fast development over the last decades of the optical setups has made available measurements of distributed in-cylinder variables such as instantaneous velocity or flame luminosity fields, with both spatial and temporal high resolution. This makes them a very powerful investigation tool for internal combustion engines (ICE). However, the interpretation of the collected – usually in impressive amounts – data can be quite challenging, mainly due to the variety of coupled phenomena taking place in the combustion chamber. This has lead to the necessity of the development of sophisticated mathematical tools which could facilitate and automatize the analysis of the in-cylinder processes. Perhaps the most notable is Proper Orthogonal Decomposition (POD) [1] – a powerful data analysis tool used to create low dimensional approximations of high dimensional systems. Among the other engineering applications, the method has been successfully applied to particle image velocimetry (PIV) fields o...
Dynamic simulations and continuation of periodic solutions are conducted to accurately describe t... more Dynamic simulations and continuation of periodic solutions are conducted to accurately describe the complex dynamic behaviour of a tubular Reverse-Flow Reactor (RFR). Spatio-temporal symmetry proprieties of the reactor model are used to understand complex phenomena and several routes to chaos. The spatio-temporal symmetry influences not only the bifurcation of periodic solution, but also the bifurcation of chaotic regimes and route to chaos. Indeed, special kinds of intermittency are observed and studied. Dynamic regimes are enhanced by the typically high exothermicity and stiff kinetics of combustion reactions. INTRODUCTION In the past 30 years, the real advantages of forced unsteady-state operations over conventional steady-state regimes of catalytic fixed-bed reactors have been widely supported (Matros & Bunimovich, 1996). Special attention has been devoted to Reverse Flow Reactors (RFR) for catalytic combustion characterized by the periodic alternation of feed introduction betwe...
Abstract The problem of the optimal design of a catalyst pellet occupied by different types of ac... more Abstract The problem of the optimal design of a catalyst pellet occupied by different types of active sites was formalized and solved for a non-isothermal system of two consecutive chemical reactions. The maximization of the desired product yield was tackled with model-order reduction techniques. Proper Orthogonal Decomposition (POD) and Discrete Empirical Interpolation Method (DEIM) were employed to reduce the catalyst pellet balance equations that need to be resolved to evaluate the objective function. It was demonstrated that the pellet performance may be significantly improved by choosing proper fractions of two types of catalytic active centers. Moreover, application of the model-order reduction procedure permitted to solve the problem with a minimal numerical effort without affecting significantly the accuracy.
The papers presented at the 2nd Symposium on Computational Combustion within ICCMSE 2017 are focu... more The papers presented at the 2nd Symposium on Computational Combustion within ICCMSE 2017 are focused on the bridging of the most advanced numerical and computational techniques to address accurate modelling of complex phenomena arising in the combustions physics and technological applications. Because of the increasing complexity of scientific and engineering combustion problems, advances in computational algorithms may indeed have a revolutionary impact on combustion science and its applications. This 2nd Topical session/Symposium on Computational Combustion, following the 1st one held in Athens in 2016, was an even more successful venue in which participants engaged fruitful discussions on common methodological aspects in a friendly atmosphere.
International Journal of Thermodynamics, Dec 1, 2013
ABSTRACT This work investigates the ideal performances that could be achieved in the coupling of ... more ABSTRACT This work investigates the ideal performances that could be achieved in the coupling of a Fluidized Bed Combustor with a Stirling engine by placing the head of a Stirling engine, more specifically the elements of the hot side heat exchanger, in direct contact with the sand of the Fluidized Bed Combustor. This choice is primarily suggested by the heat exchange coefficients between the multiphase fluidized bed medium and the surface of the heat exchanger, much larger than those attained when the heat exchanger is located in the stream of hot flue gases. Moreover, the mechanical action exerted by the fluidized solid particles substantially reduces the fouling usually caused by impurities in exhaust gases of a biomass combustion process. A mathematical model, which covers a small size fluidized bed and the Stirling engine, is developed and used to optimize design and operating conditions with specific attention to the Stirling hot side heat exchanger. It is shown that the choice to place the heat exchanger in direct contact with the fluidized bed can lead to an improvement of performance in terms of efficiency and shaft power output, making the development of this kind of system attractive for the production of energy from renewable sources.
Abstract The structure of a catalytic reactor integrating two reactions is yield-optimized in ter... more Abstract The structure of a catalytic reactor integrating two reactions is yield-optimized in terms of distribution of active sites of two catalysts in a hybrid pellet, using a two-scale (pellet and reactor) approach. POD-Galerkin model reduction is adopted to reduce the burden of the optimization algorithm. Results show that optimal structuring can have a key role in catalyst process intensification, in terms of yield, chosen as the performance indicator and thus also as the objective function for the optimization problem.
A fast development over the last decades of the optical setups has made available measurements of... more A fast development over the last decades of the optical setups has made available measurements of distributed in-cylinder variables such as instantaneous velocity or flame luminosity fields, with both spatial and temporal high resolution. This makes them a very powerful investigation tool for internal combustion engines (ICE). However, the interpretation of the collected – usually in impressive amounts – data can be quite challenging, mainly due to the variety of coupled phenomena taking place in the combustion chamber. This has lead to the necessity of the development of sophisticated mathematical tools which could facilitate and automatize the analysis of the in-cylinder processes. Perhaps the most notable is Proper Orthogonal Decomposition (POD) [1] – a powerful data analysis tool used to create low dimensional approximations of high dimensional systems. Among the other engineering applications, the method has been successfully applied to particle image velocimetry (PIV) fields o...
Dynamic simulations and continuation of periodic solutions are conducted to accurately describe t... more Dynamic simulations and continuation of periodic solutions are conducted to accurately describe the complex dynamic behaviour of a tubular Reverse-Flow Reactor (RFR). Spatio-temporal symmetry proprieties of the reactor model are used to understand complex phenomena and several routes to chaos. The spatio-temporal symmetry influences not only the bifurcation of periodic solution, but also the bifurcation of chaotic regimes and route to chaos. Indeed, special kinds of intermittency are observed and studied. Dynamic regimes are enhanced by the typically high exothermicity and stiff kinetics of combustion reactions. INTRODUCTION In the past 30 years, the real advantages of forced unsteady-state operations over conventional steady-state regimes of catalytic fixed-bed reactors have been widely supported (Matros & Bunimovich, 1996). Special attention has been devoted to Reverse Flow Reactors (RFR) for catalytic combustion characterized by the periodic alternation of feed introduction betwe...
Abstract The problem of the optimal design of a catalyst pellet occupied by different types of ac... more Abstract The problem of the optimal design of a catalyst pellet occupied by different types of active sites was formalized and solved for a non-isothermal system of two consecutive chemical reactions. The maximization of the desired product yield was tackled with model-order reduction techniques. Proper Orthogonal Decomposition (POD) and Discrete Empirical Interpolation Method (DEIM) were employed to reduce the catalyst pellet balance equations that need to be resolved to evaluate the objective function. It was demonstrated that the pellet performance may be significantly improved by choosing proper fractions of two types of catalytic active centers. Moreover, application of the model-order reduction procedure permitted to solve the problem with a minimal numerical effort without affecting significantly the accuracy.
The papers presented at the 2nd Symposium on Computational Combustion within ICCMSE 2017 are focu... more The papers presented at the 2nd Symposium on Computational Combustion within ICCMSE 2017 are focused on the bridging of the most advanced numerical and computational techniques to address accurate modelling of complex phenomena arising in the combustions physics and technological applications. Because of the increasing complexity of scientific and engineering combustion problems, advances in computational algorithms may indeed have a revolutionary impact on combustion science and its applications. This 2nd Topical session/Symposium on Computational Combustion, following the 1st one held in Athens in 2016, was an even more successful venue in which participants engaged fruitful discussions on common methodological aspects in a friendly atmosphere.
Proceedings of the of the 2 nd Symposium on Computational Combustion, 2017
The papers presented at the 2nd Symposium on Computational Combustion within ICCMSE 2017 are focu... more The papers presented at the 2nd Symposium on Computational Combustion within ICCMSE 2017 are focused on the bridging of the most advanced numerical and computational techniques to address accurate modelling of complex phenomena arising in the combustions physics and technological applications. Because of the increasing complexity of scientific and engineering combustion problems, advances in computational algorithms may indeed have a revolutionary impact on combustion science and its applications. This 2nd Topical session/Symposium on Computational Combustion, following the 1st one held in Athens in 2016, was an even more successful venue in which participants engaged fruitful discussions on common methodological aspects in a friendly atmosphere.
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Papers by Gaetano Continillo