The Experts below are selected from a list of 5106 Experts worldwide ranked by ideXlab platform
Jaume Fito - One of the best experts on this subject based on the ideXlab platform.
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hybrid system combining mechanical compression and thermochemical storage of ammonia vapor for cold production
Energy Conversion and Management, 2019Co-Authors: Jaume Fito, Nathalie Mazet, Maxime Periermuzet, Alberto Coronas, Sylvain Mauran, Driss StitouAbstract:Abstract This paper studies a hybrid system for cold production consisting of a compression cycle combined with a thermochemical process by sharing the same condenser, evaporator and Refrigerant Fluid. The aim of this hybridization is to solve mismatch issues between the demand of cold and the source of energy (availability and/or price) with a system as compact as possible. One important side benefit is that the interaction between the compressor and the thermochemical reactor reduces the activation temperature for ammonia desorption in the thermochemical reactor. To study this interaction a quasi-steady simulation model for both storage and de-storage phases has been developed and experimentally validated by means of a small scale (approx. 300 Wh of cold storage) experimental bench with ammonia as Refrigerant and barium chloride (BaCl 2 ) as reactant salt. Experiments proved a 35 K reduction in the activation temperature of the desorption reaction with respect to desorption without compressor. Model validation by adjusting permeability and thermal conductivity of the reactive composite showed an acceptable agreement between predicted and experimental reaction advancement-time curves. The validated model was used for simulation of the system in a preliminary case study, representative in power (40 kW) and temperature (−25 °C) of an industrial cold demand. It is shown that during ammonia de-storage, the hybrid achieves a higher COP than a conventional mechanical vapor compression system. It increases exponentially with the relative share of thermochemical storage in the cold production.
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definition and performance simulations of a novel solar driven hybrid absorption thermochemical refrigeration system
Energy Conversion and Management, 2018Co-Authors: Jaume Fito, Nathalie Mazet, Alberto Coronas, Sylvain Mauran, Driss StitouAbstract:Abstract This paper proposes a novel hybrid refrigeration system with energy storage, driven by low-grade solar heat and consisting of a single-stage absorption cycle coupled with a thermochemical process by sharing the same condenser, evaporator and Refrigerant Fluid. A first screening of ammonia-based working pairs for evaporation temperatures of −10 °C, condensation temperatures of 30 °C and heat source temperatures of 80 °C reveals LiNO 3 as suitable sorbent salt for the absorption subsystem, and BaCl 2 , PbBr 2 , SrCl 2 , LiCl, NH 4 Br and SnCl 2 as candidate reactive salts in the thermochemical subsystem. The subsequent parametric study indicates that the absorption subsystem with NH 3 /LiNO 3 reaches close-to-maximum COP at the indicated conditions, and the thermochemical subsystem delivers its highest COP with the NH 3 /BaCl 2 pair. Then, the power-storage and performance-storage relationships of the thermochemical subsystem are analyzed for the NH 3 /BaCl 2 pair with respect to variations in operating conditions and several implementation parameters of the reactive composite. Finally, the performance of the hybrid system with the (NH 3 /LiNO 3 + NH 3 /BaCl 2 ) pair combination is compared to its subsystems against a variable demand profile calculated from climatic data of July in Barcelona, Spain. A novel indicator is defined to assess demand coverage: the Coefficient of Satisfaction of Demand (CSD). Depending on solar collector field area and amount of Refrigerant storable by the thermochemical subsystem, the hybrid system reaches up to 24% higher CSD than the reference system (a solar single-stage absorption refrigerator with no storage), and at least 14% higher COP than the thermochemical process.
Sylvain Mauran - One of the best experts on this subject based on the ideXlab platform.
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hybrid system combining mechanical compression and thermochemical storage of ammonia vapor for cold production
Energy Conversion and Management, 2019Co-Authors: Jaume Fito, Nathalie Mazet, Maxime Periermuzet, Alberto Coronas, Sylvain Mauran, Driss StitouAbstract:Abstract This paper studies a hybrid system for cold production consisting of a compression cycle combined with a thermochemical process by sharing the same condenser, evaporator and Refrigerant Fluid. The aim of this hybridization is to solve mismatch issues between the demand of cold and the source of energy (availability and/or price) with a system as compact as possible. One important side benefit is that the interaction between the compressor and the thermochemical reactor reduces the activation temperature for ammonia desorption in the thermochemical reactor. To study this interaction a quasi-steady simulation model for both storage and de-storage phases has been developed and experimentally validated by means of a small scale (approx. 300 Wh of cold storage) experimental bench with ammonia as Refrigerant and barium chloride (BaCl 2 ) as reactant salt. Experiments proved a 35 K reduction in the activation temperature of the desorption reaction with respect to desorption without compressor. Model validation by adjusting permeability and thermal conductivity of the reactive composite showed an acceptable agreement between predicted and experimental reaction advancement-time curves. The validated model was used for simulation of the system in a preliminary case study, representative in power (40 kW) and temperature (−25 °C) of an industrial cold demand. It is shown that during ammonia de-storage, the hybrid achieves a higher COP than a conventional mechanical vapor compression system. It increases exponentially with the relative share of thermochemical storage in the cold production.
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definition and performance simulations of a novel solar driven hybrid absorption thermochemical refrigeration system
Energy Conversion and Management, 2018Co-Authors: Jaume Fito, Nathalie Mazet, Alberto Coronas, Sylvain Mauran, Driss StitouAbstract:Abstract This paper proposes a novel hybrid refrigeration system with energy storage, driven by low-grade solar heat and consisting of a single-stage absorption cycle coupled with a thermochemical process by sharing the same condenser, evaporator and Refrigerant Fluid. A first screening of ammonia-based working pairs for evaporation temperatures of −10 °C, condensation temperatures of 30 °C and heat source temperatures of 80 °C reveals LiNO 3 as suitable sorbent salt for the absorption subsystem, and BaCl 2 , PbBr 2 , SrCl 2 , LiCl, NH 4 Br and SnCl 2 as candidate reactive salts in the thermochemical subsystem. The subsequent parametric study indicates that the absorption subsystem with NH 3 /LiNO 3 reaches close-to-maximum COP at the indicated conditions, and the thermochemical subsystem delivers its highest COP with the NH 3 /BaCl 2 pair. Then, the power-storage and performance-storage relationships of the thermochemical subsystem are analyzed for the NH 3 /BaCl 2 pair with respect to variations in operating conditions and several implementation parameters of the reactive composite. Finally, the performance of the hybrid system with the (NH 3 /LiNO 3 + NH 3 /BaCl 2 ) pair combination is compared to its subsystems against a variable demand profile calculated from climatic data of July in Barcelona, Spain. A novel indicator is defined to assess demand coverage: the Coefficient of Satisfaction of Demand (CSD). Depending on solar collector field area and amount of Refrigerant storable by the thermochemical subsystem, the hybrid system reaches up to 24% higher CSD than the reference system (a solar single-stage absorption refrigerator with no storage), and at least 14% higher COP than the thermochemical process.
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solar heating and cooling by a thermochemical process first experiments of a prototype storing 60 kw h by a solid gas reaction
Solar Energy, 2008Co-Authors: Sylvain Mauran, H Lahmidi, V GoetzAbstract:Abstract The chemical heat pumps using monovariant solid/gas reactions and thermal solar energy are potentially interesting for the air-conditioning of building (heating in winter or mid-season and refreshing in summer). They provide a function of storage without loss and potentially at high energy density. The selected reaction involves SrBr2 as reactant and H2O as Refrigerant Fluid. It is adapted to the thermodynamic constraints in temperature (heat provided by plane solar collector, heating and cooling on the level of the floor) and uses reagents having a weak impact for the environment and health. The reactive salt SrBr2 is implemented with an expanded natural graphite in the form of a consolidated material which has acceptable thermal conductivity and permeability adapted to low pressure. The prototype reactor has a total volume of 1 m3. It is able to store, with a complete reaction, 60 kW h or 40 kW h for the heating or cooling function respectively. This prototype was tested under conditions representative of summer or mid-season; the mean heating or cooling powers, typically about 2.5–4 kW, are still insufficient because of a low heat transfer at the interface between the reactive layer and the exchanger wall. However this limitation can be clearly attenuated; that is the subject of current work in following these first experiments.
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definition test and simulation of a thermochemical storage process adapted to solar thermal systems
Solar Energy, 2006Co-Authors: H Lahmidi, Sylvain Mauran, V GoetzAbstract:Abstract The increase in the use of solar energy closely depends on the development of efficient storage processes. Solid–gas sorption processes are a promising option as they offer a high storage capacity and their specific working mode. In this paper, the integration of a sorption process based on the use of bromide strontium as the reactant and water as the Refrigerant Fluid is investigated. Combined with flat plate solar collectors and direct floor heating and cooling, the system makes it possible to provide a heating and a cooling storage function. Experimental tests have been conducted in the temperature ranges used in the solar heating and cooling systems. A simple model is proposed which allows an estimation of the performances in line with the heat and mass transfer characteristics of the reactive solid.
Flox Chillarón Gonzalo - One of the best experts on this subject based on the ideXlab platform.
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Caracterización numérica de un eyector de geometría variable equipado en ciclos de refrigeración accionados por fuentes térmicas de baja temperatura
'Universitat Politecnica de Valencia', 2020Co-Authors: Flox Chillarón GonzaloAbstract:[ES] El presente proyecto tiene como objetivo caracterizar la envolvente de operación de un eyector de geometría variable mediante técnicas de mecánica de Fluidos computacional. El eyector opera con el Fluido Refrigerante R1234yf y está ideado para ser implementado en un ciclo de refrigeración accionado por fuentes de calor de baja temperatura. Se pretende modificar activamente la geometría del eyector para hacer frente a cambios en las condiciones de condensación, íntimamente ligadas con los cambios en la temperatura ambiente, así como en las condiciones en el generador, directamente relacionadas con la disponibilidad de calor en la fuente térmica.[EN] In the present project the operation envelope of a variable geometry ejector is calculated using computational Fluid mechanics techniques. In addition, the differences between the entrainment ratio provided by a variable geometry ejector and a fixed geometry ejector are studied. The entrainment ratio is selected as a study variable, since the overall performance of the cycle is proportional to this parameter. The ejector operates with R1234yf as the Refrigerant Fluid and is geometrically optimised to integrate it into a refrigeration cycle driven by low temperature heat sources. The geometry of the ejector is actively modified by a needle to adapt to changes in condensing conditions, closely linked to changes in ambient temperature, as well as to changes in conditions in the generator, directly related to the availability of heat in the heat source.Flox Chillarón, G. (2020). Caracterización numérica de un eyector de geometría variable equipado en ciclos de refrigeración accionados por fuentes térmicas de baja temperatura. http://hdl.handle.net/10251/151251TFG
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Caracterización numérica de un eyector de geometría variable equipado en ciclos de refrigeración accionados por fuentes térmicas de baja temperatura
'Universitat Politecnica de Valencia', 2020Co-Authors: Flox Chillarón GonzaloAbstract:[ES] El presente proyecto tiene como objetivo caracterizar la envolvente de operación de un eyector de geometría variable mediante técnicas de mecánica de Fluidos computacional. El eyector opera con el Fluido Refrigerante R1234yf y está ideado para ser implementado en un ciclo de refrigeración accionado por fuentes de calor de baja temperatura. Se pretende modificar activamente la geometría del eyector para hacer frente a cambios en las condiciones de condensación, íntimamente ligadas con los cambios en la temperatura ambiente, así como en las condiciones en el generador, directamente relacionadas con la disponibilidad de calor en la fuente térmica.[EN] In the present project the operation envelope of a variable geometry ejector is calculated using computational Fluid mechanics techniques. In addition, the differences between the entrainment ratio provided by a variable geometry ejector and a fixed geometry ejector are studied. The entrainment ratio is selected as a study variable, since the overall performance of the cycle is proportional to this parameter. The ejector operates with R1234yf as the Refrigerant Fluid and is geometrically optimised to integrate it into a refrigeration cycle driven by low temperature heat sources. The geometry of the ejector is actively modified by a needle to adapt to changes in condensing conditions, closely linked to changes in ambient temperature, as well as to changes in conditions in the generator, directly related to the availability of heat in the heat source.Flox Chillarón, G. (2020). Caracterización numérica de un eyector de geometría variable equipado en ciclos de refrigeración accionados por fuentes térmicas de baja temperatura. Universitat Politècnica de València. http://hdl.handle.net/10251/151251TFG
Driss Stitou - One of the best experts on this subject based on the ideXlab platform.
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hybrid system combining mechanical compression and thermochemical storage of ammonia vapor for cold production
Energy Conversion and Management, 2019Co-Authors: Jaume Fito, Nathalie Mazet, Maxime Periermuzet, Alberto Coronas, Sylvain Mauran, Driss StitouAbstract:Abstract This paper studies a hybrid system for cold production consisting of a compression cycle combined with a thermochemical process by sharing the same condenser, evaporator and Refrigerant Fluid. The aim of this hybridization is to solve mismatch issues between the demand of cold and the source of energy (availability and/or price) with a system as compact as possible. One important side benefit is that the interaction between the compressor and the thermochemical reactor reduces the activation temperature for ammonia desorption in the thermochemical reactor. To study this interaction a quasi-steady simulation model for both storage and de-storage phases has been developed and experimentally validated by means of a small scale (approx. 300 Wh of cold storage) experimental bench with ammonia as Refrigerant and barium chloride (BaCl 2 ) as reactant salt. Experiments proved a 35 K reduction in the activation temperature of the desorption reaction with respect to desorption without compressor. Model validation by adjusting permeability and thermal conductivity of the reactive composite showed an acceptable agreement between predicted and experimental reaction advancement-time curves. The validated model was used for simulation of the system in a preliminary case study, representative in power (40 kW) and temperature (−25 °C) of an industrial cold demand. It is shown that during ammonia de-storage, the hybrid achieves a higher COP than a conventional mechanical vapor compression system. It increases exponentially with the relative share of thermochemical storage in the cold production.
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definition and performance simulations of a novel solar driven hybrid absorption thermochemical refrigeration system
Energy Conversion and Management, 2018Co-Authors: Jaume Fito, Nathalie Mazet, Alberto Coronas, Sylvain Mauran, Driss StitouAbstract:Abstract This paper proposes a novel hybrid refrigeration system with energy storage, driven by low-grade solar heat and consisting of a single-stage absorption cycle coupled with a thermochemical process by sharing the same condenser, evaporator and Refrigerant Fluid. A first screening of ammonia-based working pairs for evaporation temperatures of −10 °C, condensation temperatures of 30 °C and heat source temperatures of 80 °C reveals LiNO 3 as suitable sorbent salt for the absorption subsystem, and BaCl 2 , PbBr 2 , SrCl 2 , LiCl, NH 4 Br and SnCl 2 as candidate reactive salts in the thermochemical subsystem. The subsequent parametric study indicates that the absorption subsystem with NH 3 /LiNO 3 reaches close-to-maximum COP at the indicated conditions, and the thermochemical subsystem delivers its highest COP with the NH 3 /BaCl 2 pair. Then, the power-storage and performance-storage relationships of the thermochemical subsystem are analyzed for the NH 3 /BaCl 2 pair with respect to variations in operating conditions and several implementation parameters of the reactive composite. Finally, the performance of the hybrid system with the (NH 3 /LiNO 3 + NH 3 /BaCl 2 ) pair combination is compared to its subsystems against a variable demand profile calculated from climatic data of July in Barcelona, Spain. A novel indicator is defined to assess demand coverage: the Coefficient of Satisfaction of Demand (CSD). Depending on solar collector field area and amount of Refrigerant storable by the thermochemical subsystem, the hybrid system reaches up to 24% higher CSD than the reference system (a solar single-stage absorption refrigerator with no storage), and at least 14% higher COP than the thermochemical process.
Adriano Pinto Mariano - One of the best experts on this subject based on the ideXlab platform.
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Modelagem deterministica de reatores de lama cataliticos trifasicos
2017Co-Authors: Adriano Pinto MarianoAbstract:Resumo: O objetivo principal deste trabalho foi o desenvolvimento de um software capaz de representar via modelagem deterministica o comportamento dinâmico de reatores de lama catalíticos trifásicos. Para alcançar uma representação realista do sistema, são utilizados modelos dinâmicos detalhados, que consistem de equações de balanço de massa e energia para as partículas do catalisador, como também para as fases líquida e gasosa. São modelos não isotérmicos e heterogêneos que incluem: as resistências à transferência de massa e calor nas interfaces gás-líquido e líquido-sólido e na partícula de catalisador; a troca térmica com o Fluido Refrigerante; e a consideração da variação das propriedades físico-químicas e coeficientes de transferência de massa e calor que são calculados através de correlações disponíveis na literatura. Os modelos foram aplicados para descrever o comportamento dinâmico do reator durante a hidrogenação do o-cresol utilizando catalisador de Ni/SiO2. Contudo, os modelos podem ser facilmente adaptados a outras reações graças à generalidade adotada durante os seus desenvolvimentos. Na prática é observada, em certas situações, a mudança de fase do meio reacional e do Fluido Refrigerante e com a finalidade de avaliar o impacto desses fenômenos no comportamento dinâmico do reator, um cálculo de flash multicomponente foi usado para reproduzir esse efeito no meio reacional, e um apropriado procedimento de correção do coeficiente global de troca térmica para analisar o efeito no Fluido Refrigerante. Questões estas pouco encontradas na literatura. Os modelos permitiram reproduzir as principais características dinâmicas do reator frente a mudanças nos parâmetros operacionais do reator e o software desenvolvido permite ao usuário considerar diversas complexidades citadas no modelo objetivando a melhor reprodução de possíveis dados obtidos numa planta química. Este conhecimento é fundamental para o desenvolvimento de uma estratégia de controle eficiente e segura e estudos de otimização e projeto do reator trifásico. O software é de autoria do autor deste trabalho e de seus orientadores, está registrado no LOPCA e só pode ser utilizado mediante autorização.Abstract: The principal aim of this work was the development of a software capable to represent via deterministic modelling the dynamic behaviour of three-phase slurry catalytic reactors. Intending to achieve a realistic representation of the system, detailed models are utilized. They consist of mass and heat balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. These non-isothermal heterogeneous models include: the resistance to mass and heat transfer at the gas-liquid and liquid-solid interface, as well as for the catalyst particle; the heat exchange with the Refrigerant Fluid; and the consideration of the variation of physicochemical properties and transfer coefficients of mass and heat that are reckoned through correlations available in the literature. The models were applied to describe the reactor dynamic behaviour during the hydrogenation of o-cresol on Ni/SiO2 catalyst. However, the models can easily be adapted to other reactions thanks to the generality adopted during their development. In practice, under specific situations, the change of phase of the reacting medium and of the Refrigerant Fluid is observed. Aiming to evaluate the impact of these phenomena in the dynamic behaviour of the reactor, a multicomponent flash calculation was used to reproduce this effect in the reacting medium and an appropriate correction procedure of the global coefficient of heat transfer to analyse the effect in the Refrigerant Fluid. The models allowed to reproduce the main dynamic characteristics of the reactor in face of several changes in operational parameters of the reactor and the developed software allows the user to consider the complexities introduced in the model with the aim of a better reproduction of possible chemical plant data. This knowledge is fundamental for the development of an efficient and safe control strategy as well as for studies of optimization and design of the three-phase reactor. The software is the property of the author of this work and his supervisors; it is registered in the LOPCA and can only be used subjected to prior authorization
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Modelagem deterministica de reatores de lama cataliticos trifasicos
Universidade Estadual de Campinas. Faculdade de Engenharia Quimica, 2003Co-Authors: Adriano Pinto MarianoAbstract:O objetivo principal deste trabalho foi o desenvolvimento de um software capaz de representar via modelagem deterministica o comportamento dinâmico de reatores de lama catalíticos trifásicos. Para alcançar uma representação realista do sistema, são utilizados modelos dinâmicos detalhados, que consistem de equações de balanço de massa e energia para as partículas do catalisador, como também para as fases líquida e gasosa. São modelos não isotérmicos e heterogêneos que incluem: as resistências à transferência de massa e calor nas interfaces gás-líquido e líquido-sólido e na partícula de catalisador; a troca térmica com o Fluido Refrigerante; e a consideração da variação das propriedades físico-químicas e coeficientes de transferência de massa e calor que são calculados através de correlações disponíveis na literatura. Os modelos foram aplicados para descrever o comportamento dinâmico do reator durante a hidrogenação do o-cresol utilizando catalisador de Ni/SiO2. Contudo, os modelos podem ser facilmente adaptados a outras reações graças à generalidade adotada durante os seus desenvolvimentos. Na prática é observada, em certas situações, a mudança de fase do meio reacional e do Fluido Refrigerante e com a finalidade de avaliar o impacto desses fenômenos no comportamento dinâmico do reator, um cálculo de flash multicomponente foi usado para reproduzir esse efeito no meio reacional, e um apropriado procedimento de correção do coeficiente global de troca térmica para analisar o efeito no Fluido Refrigerante. Questões estas pouco encontradas na literatura. Os modelos permitiram reproduzir as principais características dinâmicas do reator frente a mudanças nos parâmetros operacionais do reator e o software desenvolvido permite ao usuário considerar diversas complexidades citadas no modelo objetivando a melhor reprodução de possíveis dados obtidos numa planta química. Este conhecimento é fundamental para o desenvolvimento de uma estratégia de controle eficiente e segura e estudos de otimização e projeto do reator trifásico. O software é de autoria do autor deste trabalho e de seus orientadores, está registrado no LOPCA e só pode ser utilizado mediante autorização.The principal aim of this work was the development of a software capable to represent via deterministic modelling the dynamic behaviour of three-phase slurry catalytic reactors. Intending to achieve a realistic representation of the system, detailed models are utilized. They consist of mass and heat balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. These non-isothermal heterogeneous models include: the resistance to mass and heat transfer at the gas-liquid and liquid-solid interface, as well as for the catalyst particle; the heat exchange with the Refrigerant Fluid; and the consideration of the variation of physicochemical properties and transfer coefficients of mass and heat that are reckoned through correlations available in the literature. The models were applied to describe the reactor dynamic behaviour during the hydrogenation of o-cresol on Ni/SiO2 catalyst. However, the models can easily be adapted to other reactions thanks to the generality adopted during their development. In practice, under specific situations, the change of phase of the reacting medium and of the Refrigerant Fluid is observed. Aiming to evaluate the impact of these phenomena in the dynamic behaviour of the reactor, a multicomponent flash calculation was used to reproduce this effect in the reacting medium and an appropriate correction procedure of the global coefficient of heat transfer to analyse the effect in the Refrigerant Fluid. The models allowed to reproduce the main dynamic characteristics of the reactor in face of several changes in operational parameters of the reactor and the developed software allows the user to consider the complexities introduced in the model with the aim of a better reproduction of possible chemical plant data. This knowledge is fundamental for the development of an efficient and safe control strategy as well as for studies of optimization and design of the three-phase reactor. The software is the property of the author of this work and his supervisors; it is registered in the LOPCA and can only be used subjected to prior authorization