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Papers by Amin El-Bakkali
Thomas GILLET, Romuald RULLIERE, Philippe HABERSCHILL, Vincent LEMORT, Emmanuelle ANDRES, Amin EL... more Thomas GILLET, Romuald RULLIERE, Philippe HABERSCHILL, Vincent LEMORT, Emmanuelle ANDRES, Amin EL-BAKKALI, Gérard OLIVIER 1 CETHIL UMR5008, Université de Lyon, CNRS, INSA-Lyon, Univ. Lyon 1, F-69621, Villeurbanne, France 2 Laboratoire de Thermodynamique et Energétique de l’Université de Liège 17, allée de la Découverte, 4000 Liège, Belgique 3 Renault SAS 1, avenue du Golf, 78288 Guyancourt, France (auteur correspondant : thomas.gillet@doct.ulg.ac.be)
An automotive multi-evaporator air conditioning system, which is composed of two evaporators and ... more An automotive multi-evaporator air conditioning system, which is composed of two evaporators and a secondary fluid cooler, was modeled using the LMS Imagine.Lab Amesim® 1D software. The present study focuses on understanding the dynamic coupling of the several loop components such as the three evaporators having different cooling capacities. This kind of multi-evaporator air-conditioning system has a number of technological barriers that must be overcome. Understanding the behavior of their respective expansion devices and the choice of these latter is also essential to control properly the transient phase and ensure an optimal operation of the air-conditioning system. In order to study the behavior of the loop, step disturbances were simulated on an operating point at medium and high load. The impact of these disturbances on the stability of the supplied cooled air temperature is analyzed for two types of expansion valve. Initial results show that the thermostatic expansion valves ...
International Journal of Refrigeration, 2018
Abstract With the arrival of electrified vehicles, the air-conditioning system has to be reconsid... more Abstract With the arrival of electrified vehicles, the air-conditioning system has to be reconsidered. Battery cooling management system and high level of comfort for passengers make the single evaporator air-conditioning system a multi-evaporator one. In a multi-evaporator air-conditioning system, evaporating pressures are equal in each evaporator so that evaporators are coupled dynamically. However, the demand in cooling capacity and temperature target can vary from each other. For an operating point with a first evaporator working at high load and a second at low partial load, thermal interaction can occur from the superheated refrigerant coming from a first evaporator to the outlet of a second evaporator. This phenomenon makes the second evaporator sleeping since its expansion valve bulb misreads the superheat and closes. Furthermore, sleeping evaporator looks like an extreme case of refrigerant maldistribution in the evaporator. Refrigerant maldistribution is then investigated to show some drawbacks and advantages multi-evaporator air-conditioning systems (MEAC) have to face or can benefit by comparing two types of expansion valve: thermostatic and electronic ones. In this paper, sleeping evaporator and refrigerant maldistribution phenomena are experimentally investigated in order to propose in the future a robust control of an automotive MEAC. A test bench was built to compare two types of expansion valves (thermostatic/electronic) and study their behaviours in steady and transient state to tackle sleeping evaporators and benefit from refrigerant maldistribution.
ArXiv, 2020
We propose a machine learning approach aiming at reducing Bond Graphs. The output of the machine ... more We propose a machine learning approach aiming at reducing Bond Graphs. The output of the machine learning is a hybrid modeling that contains a reduced Bond Graph coupled to a simple artificial neural network. The proposed coupling enables knowledge continuity in machine learning. In this paper, a neural network is obtained by a linear calibration procedure. We propose a method that contains two training steps. First, the method selects the components of the original Bond Graph that are kept in the Reduced Bond Graph. Secondly, the method builds an artificial neural network that supplements the reduced Bond Graph. Because the output of the machine learning is a hybrid model, not solely data, it becomes difficult to use a usual Backpropagation Through Time to calibrate the weights of the neural network. So, in a first attempt, a very simple neural network is proposed by following a model reduction approach. We consider the modeling of the automotive cabins thermal behavior. The data u...
MATHMOD 2018 Extended Abstract Volume, 2018
Entropy, 2012
In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful ... more In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature T hs ) and a heat sink (at temperature T cs ). We will show in this paper that the approach detailed in a previous paper [1] can be used to analytically model irreversible heat engines (with an additional assumption on the linearity of the heat transfer laws). By defining two dimensionless parameters, the intensity of internal dissipation and heat leakage within a heat engine were quantified. We then established the analogy between an endoreversible heat engine and an irreversible heat engine by using the apparent temperatures (T cs
ABSTRACT It is well known that, when using a passenger car with an ICE (Internal Combustion Engin... more ABSTRACT It is well known that, when using a passenger car with an ICE (Internal Combustion Engine), only a fraction of the burnt fuel energy actually contributes to drive the vehicle. Typical passenger vehicle engines run about 25% efficiency while a great part of the remaining energy (about 40%), is lost through the exhaust gases. This latter has a significant energy conversion potential since the temperature (more than 300°C) and the mass flow rate are high enough. Thus, direct conversion of heat into electricity is a credible option if the overall system is optimized. This point is crucial since the heat conversion into work process is very sensible to any mismatching of the different parts of the system, and very sensible significant to the possible varying working conditions. All these effects constitute irreversibility sources that degrade the overall efficiency. The exergetic analysis is known to be an efficient tool for finding the root causes of theses irreversible processes. In order to investigate the performance of our automotive thermo-generator we propose an analysis of the exergy flow through the system under dynamic conditions. Taking into account the different irreversible sources such as thermal conduction and Joule effect, we are able to localize and quantify the exergy losses. Then, in order to optimize the thermoelectric converter for a given vehicle, correct actions in term of design and working conditions can be proposed.
Entropy, 2012
In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful ... more In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature T hs ) and a heat sink (at temperature T cs ). We will show in this paper that the approach detailed in a previous paper [1] can be used to analytically model irreversible heat engines (with an additional assumption on the linearity of the heat transfer laws). By defining two dimensionless parameters, the intensity of internal dissipation and heat leakage within a heat engine were quantified. We then established the analogy between an endoreversible heat engine and an irreversible heat engine by using the apparent temperatures (T cs
Applied Thermal Engineering, 2011
The objective of this work relates to the reduction of the CO 2 emissions of a vehicle with a glo... more The objective of this work relates to the reduction of the CO 2 emissions of a vehicle with a global thermal optimization approach where the optimization criterion is based on exergy analysis. A numerical model gathering, under the same simulation environment, the models of the power train, the cooling circuit and the thermal behavior of the engine was developed to predict the energy interactions between the systems. The simulation tool is of modular technological level and based on the bond graph concept. A bond graph is a graphical representation of a physical dynamic system. This tool provides a comprehensive graphical user interface allowing future extensions. The simulations carried out in transient mode make it possible to evaluate the performance of various solutions for the thermal management of the vehicle.
Entropy, 2012
In recent decades, the approach known as Finite-Time Thermodynamics has provided a fruitful theor... more In recent decades, the approach known as Finite-Time Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature hs T ) and a heat sink (at temperature cs T ). The aim of this paper is to propose a more complete approach based on the association of Finite-Time Thermodynamics and the Bond-Graph approach for modeling endoreversible heat engines. This approach makes it possible for example to find in a simple way the characteristics of the optimal operating point at which the maximum mechanical power of the endoreversible heat engine is obtained with entropy flow rate as control variable. Furthermore it provides the analytical expressions of the optimal operating point of an irreversible heat engine where the energy conversion is accompanied by irreversibilities related to internal heat transfer and heat dissipation phenomena. This original approach, applied to an analysis of the performance of a thermoelectric generator, will be the object of a future publication.
Thomas GILLET, Romuald RULLIERE, Philippe HABERSCHILL, Vincent LEMORT, Emmanuelle ANDRES, Amin EL... more Thomas GILLET, Romuald RULLIERE, Philippe HABERSCHILL, Vincent LEMORT, Emmanuelle ANDRES, Amin EL-BAKKALI, Gérard OLIVIER 1 CETHIL UMR5008, Université de Lyon, CNRS, INSA-Lyon, Univ. Lyon 1, F-69621, Villeurbanne, France 2 Laboratoire de Thermodynamique et Energétique de l’Université de Liège 17, allée de la Découverte, 4000 Liège, Belgique 3 Renault SAS 1, avenue du Golf, 78288 Guyancourt, France (auteur correspondant : thomas.gillet@doct.ulg.ac.be)
An automotive multi-evaporator air conditioning system, which is composed of two evaporators and ... more An automotive multi-evaporator air conditioning system, which is composed of two evaporators and a secondary fluid cooler, was modeled using the LMS Imagine.Lab Amesim® 1D software. The present study focuses on understanding the dynamic coupling of the several loop components such as the three evaporators having different cooling capacities. This kind of multi-evaporator air-conditioning system has a number of technological barriers that must be overcome. Understanding the behavior of their respective expansion devices and the choice of these latter is also essential to control properly the transient phase and ensure an optimal operation of the air-conditioning system. In order to study the behavior of the loop, step disturbances were simulated on an operating point at medium and high load. The impact of these disturbances on the stability of the supplied cooled air temperature is analyzed for two types of expansion valve. Initial results show that the thermostatic expansion valves ...
International Journal of Refrigeration, 2018
Abstract With the arrival of electrified vehicles, the air-conditioning system has to be reconsid... more Abstract With the arrival of electrified vehicles, the air-conditioning system has to be reconsidered. Battery cooling management system and high level of comfort for passengers make the single evaporator air-conditioning system a multi-evaporator one. In a multi-evaporator air-conditioning system, evaporating pressures are equal in each evaporator so that evaporators are coupled dynamically. However, the demand in cooling capacity and temperature target can vary from each other. For an operating point with a first evaporator working at high load and a second at low partial load, thermal interaction can occur from the superheated refrigerant coming from a first evaporator to the outlet of a second evaporator. This phenomenon makes the second evaporator sleeping since its expansion valve bulb misreads the superheat and closes. Furthermore, sleeping evaporator looks like an extreme case of refrigerant maldistribution in the evaporator. Refrigerant maldistribution is then investigated to show some drawbacks and advantages multi-evaporator air-conditioning systems (MEAC) have to face or can benefit by comparing two types of expansion valve: thermostatic and electronic ones. In this paper, sleeping evaporator and refrigerant maldistribution phenomena are experimentally investigated in order to propose in the future a robust control of an automotive MEAC. A test bench was built to compare two types of expansion valves (thermostatic/electronic) and study their behaviours in steady and transient state to tackle sleeping evaporators and benefit from refrigerant maldistribution.
ArXiv, 2020
We propose a machine learning approach aiming at reducing Bond Graphs. The output of the machine ... more We propose a machine learning approach aiming at reducing Bond Graphs. The output of the machine learning is a hybrid modeling that contains a reduced Bond Graph coupled to a simple artificial neural network. The proposed coupling enables knowledge continuity in machine learning. In this paper, a neural network is obtained by a linear calibration procedure. We propose a method that contains two training steps. First, the method selects the components of the original Bond Graph that are kept in the Reduced Bond Graph. Secondly, the method builds an artificial neural network that supplements the reduced Bond Graph. Because the output of the machine learning is a hybrid model, not solely data, it becomes difficult to use a usual Backpropagation Through Time to calibrate the weights of the neural network. So, in a first attempt, a very simple neural network is proposed by following a model reduction approach. We consider the modeling of the automotive cabins thermal behavior. The data u...
MATHMOD 2018 Extended Abstract Volume, 2018
Entropy, 2012
In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful ... more In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature T hs ) and a heat sink (at temperature T cs ). We will show in this paper that the approach detailed in a previous paper [1] can be used to analytically model irreversible heat engines (with an additional assumption on the linearity of the heat transfer laws). By defining two dimensionless parameters, the intensity of internal dissipation and heat leakage within a heat engine were quantified. We then established the analogy between an endoreversible heat engine and an irreversible heat engine by using the apparent temperatures (T cs
ABSTRACT It is well known that, when using a passenger car with an ICE (Internal Combustion Engin... more ABSTRACT It is well known that, when using a passenger car with an ICE (Internal Combustion Engine), only a fraction of the burnt fuel energy actually contributes to drive the vehicle. Typical passenger vehicle engines run about 25% efficiency while a great part of the remaining energy (about 40%), is lost through the exhaust gases. This latter has a significant energy conversion potential since the temperature (more than 300°C) and the mass flow rate are high enough. Thus, direct conversion of heat into electricity is a credible option if the overall system is optimized. This point is crucial since the heat conversion into work process is very sensible to any mismatching of the different parts of the system, and very sensible significant to the possible varying working conditions. All these effects constitute irreversibility sources that degrade the overall efficiency. The exergetic analysis is known to be an efficient tool for finding the root causes of theses irreversible processes. In order to investigate the performance of our automotive thermo-generator we propose an analysis of the exergy flow through the system under dynamic conditions. Taking into account the different irreversible sources such as thermal conduction and Joule effect, we are able to localize and quantify the exergy losses. Then, in order to optimize the thermoelectric converter for a given vehicle, correct actions in term of design and working conditions can be proposed.
Entropy, 2012
In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful ... more In recent decades, the approach known as Finite-Dimension Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature T hs ) and a heat sink (at temperature T cs ). We will show in this paper that the approach detailed in a previous paper [1] can be used to analytically model irreversible heat engines (with an additional assumption on the linearity of the heat transfer laws). By defining two dimensionless parameters, the intensity of internal dissipation and heat leakage within a heat engine were quantified. We then established the analogy between an endoreversible heat engine and an irreversible heat engine by using the apparent temperatures (T cs
Applied Thermal Engineering, 2011
The objective of this work relates to the reduction of the CO 2 emissions of a vehicle with a glo... more The objective of this work relates to the reduction of the CO 2 emissions of a vehicle with a global thermal optimization approach where the optimization criterion is based on exergy analysis. A numerical model gathering, under the same simulation environment, the models of the power train, the cooling circuit and the thermal behavior of the engine was developed to predict the energy interactions between the systems. The simulation tool is of modular technological level and based on the bond graph concept. A bond graph is a graphical representation of a physical dynamic system. This tool provides a comprehensive graphical user interface allowing future extensions. The simulations carried out in transient mode make it possible to evaluate the performance of various solutions for the thermal management of the vehicle.
Entropy, 2012
In recent decades, the approach known as Finite-Time Thermodynamics has provided a fruitful theor... more In recent decades, the approach known as Finite-Time Thermodynamics has provided a fruitful theoretical framework for the optimization of heat engines operating between a heat source (at temperature hs T ) and a heat sink (at temperature cs T ). The aim of this paper is to propose a more complete approach based on the association of Finite-Time Thermodynamics and the Bond-Graph approach for modeling endoreversible heat engines. This approach makes it possible for example to find in a simple way the characteristics of the optimal operating point at which the maximum mechanical power of the endoreversible heat engine is obtained with entropy flow rate as control variable. Furthermore it provides the analytical expressions of the optimal operating point of an irreversible heat engine where the energy conversion is accompanied by irreversibilities related to internal heat transfer and heat dissipation phenomena. This original approach, applied to an analysis of the performance of a thermoelectric generator, will be the object of a future publication.