References of "Lemort, Vincent"
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See detailDesigning an air-to-air heat exchanger dedicated to single room ventilation with heat recovery
Gendebien, Samuel ULg; Martens, Jonathan; Prieels, Luc et al

in Building Simulation: An International Journal (in press)

The present paper focuses on the development steps of heat exchangers dedicated to single room ventilation unit with heat recovery (SRVHR) by proposing a numerical approach. A methodology is suggested in ... [more ▼]

The present paper focuses on the development steps of heat exchangers dedicated to single room ventilation unit with heat recovery (SRVHR) by proposing a numerical approach. A methodology is suggested in order to determine the best trade-off between hydraulic and thermal performance given a specific geometry. The methodology consists in a mapping of the coefficient of performance (COP) of the unit. The latter is defined as the ratio between recovered heat and the fan energy use, given a specific indoor/outdoor temperature difference. However, the energy performance should not be the only criterion to be taken into account in the frame of the design steps of a heat recovery exchanger: technical, economic and acoustic aspects should also be considered. This numerical methodology is illustrated by means of a real example of a newly developed heat exchanger dedicated to a SRVHR. The optimization is first performed while using a semi-empirical model (based on the use of correlations and on a spatial division of the studied heat exchanger). The semi-empirical model allows for the creation of a COP map in order to identify the most effective geometry parameters for the heat exchanger. The decision concerning the final geometry is made accounting for the so-called technical, economic and acoustic considerations. A discussion on some parameters needed for the COP establishment is also proposed. [less ▲]

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See detailAggregation of flexible domestic heat pumps for the provision of reserve in power systems
Georges, Emeline ULg; Quoilin, Sylvain ULg; Mathieu, Sébastien ULg et al

in Proceedings of the 30th International Conference on Efficiency, Cost, Optimisation, Simulation and Environmental Impact of Energy Systems. (2017, July)

The integration of renewable energy sources in the electricity production mix has an important impact on the management of the electricity grid, due to their intermittency. In particular, there is a ... [more ▼]

The integration of renewable energy sources in the electricity production mix has an important impact on the management of the electricity grid, due to their intermittency. In particular, there is a rising need for flexibility, both on the supply and demand sides. This paper assesses the amount of flexibility that could be reserved from a set of flexible residential heat pumps in a given geographical area. It addresses the problem of a load aggregator controlling a set of heat pumps used to provide both space-heating and domestic hot water. The flexibility of the heat pumps is unlocked in order to reduce electricity procurement costs in the day-ahead electricity market, while ensuring the provision of a predefined amount of reserve for real-time grid management. The objective of the paper is two-fold. On the one hand, an aggregation method of large sets of heat pumps based on physics-based models and random sampling techniques is proposed. On the other hand, a combined optimization problem is formulated to determine both the optimal electricity demand profile to be bought on the day-ahead market and the cost associated to the reservation of a defined amount of power. The method is applied to a set of 40000 residential heat pumps in Belgian houses. Results show that these houses can provide up to 100MW of upward reserve for 50% of the current costs. The provision of downward reserve at competitive cost is hampered by significant overconsumption. [less ▲]

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See detailDevelopment of an Ericsson Heat Engine for biomass Combined Heat and Power
Oudkerk, Jean-François ULg; Lemort, Vincent ULg

in Proceedings of the 30th International conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS) (2017, July)

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See detailDesign and experimental validation of an adaptive control law to maximize power generation of a small-scale waste heat recovery system
Hernandez Naranjo, Jairo Andrés ULg; Desideri, Adriano ULg; Gusev, Sergei et al

in Applied Energy (2017), 203

Increasing the energy efficiency of industrial processes is a challenge that involves, not only improving the methodologies for design and manufacturing, but optimizing performance during part-load ... [more ▼]

Increasing the energy efficiency of industrial processes is a challenge that involves, not only improving the methodologies for design and manufacturing, but optimizing performance during part-load operation and transient conditions. A well-adopted solution consists of developing waste heat recovery (WHR) systems based on Organic Rankine Cycle (ORC) power units. The highest efficiency for such cycle is obtained at low superheating values, corresponding to the situation where the system exhibits time-varying nonlinear dynamics, triggered by the fluctuating nature of the waste heat source. In this paper, an adaptive control law using the Model Predictive Control (MPC) framework is proposed. This work goes a step beyond most of the existing scientific works in the field of ORC power systems, since the MPC controller is implemented in a lab-scale prototype, and its performance compared against a gain-scheduled PID strategy. The experimental results show that the adaptive MPC outperforms the gain-scheduled PID based strategy, as it allows to accurately regulate the evaporating temperature, while keeping vapor condition at the inlet of the expander i.e., the superheating, in a safe operating range, thus increasing the net power generation. [less ▲]

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See detailWaste Heat Recovery by Means of Organic Rankine Cycle (ORC) System Coupled with Two-Phase Closed Thermosyphons
Le, Van Long ULg; Declaye, Sébastien ULg; Dumas, Xavier et al

in International Journal of Thermodynamics (2017)

This paper aims at assessing the performance of a waste heat-to-power plant by means of an ORC (Organic Rankine Cycle) system coupled with two-phase closed thermosyphons (or gravity-assisted heat pipes or ... [more ▼]

This paper aims at assessing the performance of a waste heat-to-power plant by means of an ORC (Organic Rankine Cycle) system coupled with two-phase closed thermosyphons (or gravity-assisted heat pipes or wickless heat pipes). The heat exchanger, made up of two-phase closed thermosyphons, is used for conveying heat from exhaust stream to ORC working fluid. In reality, a hot oil loop or a pressurized hot water loop or a saturated ste am loop or even a direct evaporator is often used to transfer heat from the heat source to the ORC system. However, installing a heat exchanger directly in the hot gas paths of ORC system evokes the concerns for the flammability and/or toxicity of organic working fluids especially when the heat source has a relatively high temperature. Also the use of an intermediate heat carrier loop such as thermal oil or saturated steam or pressurized water loop is costly and involves installation of comparatively heavy components. In principle, the use of two-phase closed thermosyphons for capturing and transporting heat from a waste heat source to organic working fluid is less expensive than utilizing an intermediate heat transfer loop and eliminates safety issues as in the case of direct installation of an ORC evaporator in the hot gas paths. [less ▲]

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See detailPERFORMANCES D’UNE MINI POMPE À CHALEUR RÉVERSIBLE FONCTIONNANT SUR L’AIR EXTRAIT : ÉTUDE NUMERIQUE ET EXPERIMENTALE
Ransy, Frédéric ULg; Gendebien, Samuel ULg; Lemort, Vincent ULg

Poster (2017, May 22)

La majeure partie de la consommation d’énergie des immeubles à appartement dits « basse énergie » est liée à la production d’eau chaude sanitaire et aux pertes par ventilation. De plus, ces immeubles sont ... [more ▼]

La majeure partie de la consommation d’énergie des immeubles à appartement dits « basse énergie » est liée à la production d’eau chaude sanitaire et aux pertes par ventilation. De plus, ces immeubles sont soumis à un risque de surchauffe non négligeable en été. Afin de minimiser leur consommation d’énergie, les systèmes HVAC utilisés dans ces bâtiments se doivent d’être performants et multitâches. Dans cette optique, l’Université de Liège teste actuellement une mini-pompe à chaleur réversible sur air extrait. Cet article présente les résultats expérimentaux obtenus en laboratoire et démontre quelles sont les variables qui influencent les performances de cette machine. Un modèle polynomial est également proposé. [less ▲]

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See detailDEVELOPPEMENT D’UN MODELE DE SYSTEME DE CLIMATISATION AUTOMOBILE MULTI-EVAPORATEURS
Gillet, Thomas ULg; Gendebien, Samuel ULg; Lemort, Vincent ULg et al

Conference (2017, May 22)

La modélisation numérique d’un climatiseur d’automobile multi-évaporateurs, composé de deux évaporateurs et d’un refroidisseur d’eau, a été réalisée à l’aide du logiciel LMS Imagine.Lab Amesim® 1D avec le ... [more ▼]

La modélisation numérique d’un climatiseur d’automobile multi-évaporateurs, composé de deux évaporateurs et d’un refroidisseur d’eau, a été réalisée à l’aide du logiciel LMS Imagine.Lab Amesim® 1D avec le fluide frigorigène R-134a. Un banc d’essai capable de reproduire les conditions extérieures d’un climatiseur automobile a été conçu afin de tester l’architecture de cette machine multi-évaporateurs avec le fluide frigorigène R-1234yf. Les bilans thermiques des premiers résultats expérimentaux sont analysés et présentés. Afin d’illustrer la complexité du contrôle d’une telle architecture en régime dynamique, l’activation d’une vanne électromagnétique dans la boucle batterie du banc d’essais est présentée. Enfin, une perturbation de type échelon a été générée dans le modèle numérique afin de vérifier si les phénomènes transitoires observés expérimentalement sont reproduits. [less ▲]

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See detailEtude expérimentale et numérique d'un échangeur destiné à la récupération de chaleur fatale sur bancs d'essais de moteurs aéronautiques
Gendebien, Samuel ULg; Guillaume, Ludovic ULg; Bellolio Domke, Sebastian Andres ULg et al

in Colloque Inter-universitaire Franco-Québécois (CIFQ 2017), 22-24 mai 2017, Saint-Lô, France (2017, May)

Aujourd’hui, d’importants efforts sont réalisés dans divers secteurs afin de diminuer la consommation en énergie. En ce qui concerne le secteur aéronautique, de nombreux tests sont réalisés sur les ... [more ▼]

Aujourd’hui, d’importants efforts sont réalisés dans divers secteurs afin de diminuer la consommation en énergie. En ce qui concerne le secteur aéronautique, de nombreux tests sont réalisés sur les moteurs afin d’assurer la sécurité du transport aérien. Dans ce contexte, il a été envisagé de récupérer, recycler et valoriser l’énergie produite par le moteur au moyen d’un échangeur placé dans la cheminée d’évacuation des gaz. Pour ce faire, un prototype de modèle réduit d’échangeur récupératif sur gaz de combustion (gaz/eau ou gaz/huile) a été conçu, fabriqué et testé. Ce papier présente les caractéristiques du modèle réduit de l’échangeur développé spécifiquement pour cette application. L’ensemble du banc d’essais et le système de mesure mis en place afin de caractériser les performances de l’échangeur sont décrits. Une analyse des résultats expérimentaux est présentée. Les tests sont notamment divisés en deux parties : établissement des performances en régime monophasique et diphasique. Notons également que les performances hydrauliques de l’échangeur ont été expérimentalement déterminées. Un modèle numérique de type semi-empirique est proposé pour prédire les performances de l’échangeur. Ce dernier nécessite un calibrage des paramètres au moyen des données expérimentales afin de prédire les performances de l’échangeur sous une grande plage de conditions opératoires. Une comparaison entre résultats numériques et expérimentaux est finalement présentée. [less ▲]

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See detailMODELISATION D’UN ECHANGEUR A THERMOSIPHONS POUR LA RECUPERATION DE CHALEUR
Le, Van Long ULg; Dumas, Xavier; Ferrand, Ludovic et al

in XIIIème Colloque Interuniversitaire Franco-Québécois sur la Thermique des Systèmes (2017, May)

Le présent travail a pour objectif de modéliser un échangeur à thermosiphons diphasiques pour transporter la chaleur d’un effluent gazeux (c.à.d. gaz de combustion) à haute température (720°C) au système ... [more ▼]

Le présent travail a pour objectif de modéliser un échangeur à thermosiphons diphasiques pour transporter la chaleur d’un effluent gazeux (c.à.d. gaz de combustion) à haute température (720°C) au système ORC (cycle organique de Rankine). Les thermosiphons sont placés dans les gaz de combustion et refroidis par le fluide de travail du système ORC (le Cyclopentane pour le cas actuel). Le débit massique des fumées et la puissance thermique de l’échangeur sont respectivement imposés de 21 kg/s et de 4.022 MWth. Le fluide organique s’évapore à une température de 200°C et quitte l’évaporateur sans surchauffe (vapeur saturée). Le modèle de simulation développé dans le logiciel EES (Engineering Equation Solver) est capable de déterminer le nombre nécessaiare de thermosiphons. L’influence des pas transversaux et longitudinaux de l’échangeur sur le nombre de thermosiphons et la perte de charge des fumées est également examinée pour les dispositions quinconces et alignées des tubes de thermosiphons. [less ▲]

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See detailModelling of organic Rankine cycle power systems in off-design conditions: an experimentally-validated comparative study
Dickes, Rémi ULg; Dumont, Olivier ULg; Daccord, Rémi et al

in Energy (2017), 123

Because of environmental issues and the depletion of fossil fuels, the world energy sector is undergoing many changes toward increased sustainability. Among the many fields of research and development ... [more ▼]

Because of environmental issues and the depletion of fossil fuels, the world energy sector is undergoing many changes toward increased sustainability. Among the many fields of research and development, power generation from low-grade heat sources is gaining interest and the organic Rankine cycle (ORC) is seen as one of the most promising technologies for such applications. In this paper, it is proposed to perform an experimentally-validated comparison of different modelling methods for the off-design simulation of ORC-based power systems. To this end, three types of modelling paradigms (namely a constant-efficiency method, a polynomial-based method and a semi-empirical method) are compared both in terms of their fitting and extrapolation capabilities. Post-processed measurements gathered on two experimental ORC facilities are used as reference for the models calibration and evaluation. The study is first applied at a component level (i.e. each component is analysed individually) and then extended to the characterization of the entire organic Rankine cycle power systems. Benefits and limi- tations of each modelling method are discussed. The results show that semi-empirical models are the most reliable for simulating the off-design working conditions of ORC systems, while constant-efficiency and polynomial-based models are both demonstrating lack of accuracy and/or robustness. [less ▲]

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See detailMulti-evaporator air-conditioning system
Gillet, Thomas ULg; Lemort, Vincent ULg; Andres, Emmanuelle et al

Conference (2017, February 14)

Regulation in terms of greenhouse gas emissions becomes more and more stringent and the fuel consumption targets decrease. In order to meet these demands, vehicle electrification has increased over the ... [more ▼]

Regulation in terms of greenhouse gas emissions becomes more and more stringent and the fuel consumption targets decrease. In order to meet these demands, vehicle electrification has increased over the last decade. With the arrival of plug-in hybrids and battery electric vehicles, efficient battery cooling system becomes a necessity and has to be integrated into the vehicle thermal management. One of the possibility is to integrate a chiller in the air conditioning system for extreme operating points. Moreover, this kind of system can be dedicated to luxury or large passenger cars for which a secondary evaporator is present to guarantee the comfort for rear passengers. The main challenge of this air-conditioning architecture is to maintain simultaneously the cabin thermal comfort via one or two evaporators on one hand and to maintain the battery cells in an ideal temperature range on the other hand. [less ▲]

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See detailDesign optimization of Rankine cycle systems for waste heat recovery from passenger car engines
Lemort, Vincent ULg; Legros, Arnaud; Dumont, Olivier ULg et al

Conference (2017, February 07)

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See detailResidential heat pump as flexible load for direct control service with parametrized duration and rebound effect
Georges, Emeline ULg; Cornélusse, Bertrand ULg; Ernst, Damien ULg et al

in Applied Energy (2017), 187

This paper addresses the problem of an aggregator controlling residential heat pumps to offer a direct control flexibility service. The service consists of a power modulation, upward or downward, that is ... [more ▼]

This paper addresses the problem of an aggregator controlling residential heat pumps to offer a direct control flexibility service. The service consists of a power modulation, upward or downward, that is activated at a given time period over a fixed number of periods. The service modulation is relative to an optimized baseline that minimizes the energy costs. The load modulation is directly followed by a constrained rebound effect, consisting of a delay time with no deviations from the baseline consumption and a payback time to return to the baseline state. The potential amount of modulation and the constrained rebound effect are computed by solving mixed integer linear problems. Within these problems, the thermal behavior of the building is modeled by an equivalent thermal network made of resistances and lumped capacitances. Simulations are performed for different sets of buildings typical of the Belgian residential building stock and are presented in terms of achievable modulation amplitude, deviations from the baseline and associated costs. A cluster of one hundred ideal buildings, corresponding to retrofitted freestanding houses, is then chosen to investigate the influence of each parameter defined within the service. Results show that with a set of one hundred heat pumps, a load aggregator could expect to harvest mean modulation amplitudes of up to 138 kW for an upward modulation and up to 51 kW for a downward modulation. The obtained values strongly depend on the proposed flexibility service. For example, they can decrease down to 2.6 kW and 0.4 kW, respectively, if no rebound effect is allowed. [less ▲]

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See detailNowate: Waste heat re-use for greener trucks
Lemort, Vincent ULg; Guillaume, Ludovic ULg; Bettoja, Federica et al

Conference (2017)

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See detailThermo-economic optimization during preliminary design phase of organic Rankine cycle systems for waste heat recovery from exhaust and recirculated gases of heavy duty trucks
Guillaume, Ludovic ULg; Legros, Arnaud; Dickes, Rémi ULg et al

in IMechE (Ed.) Vehicle Thermal Management Systems conference (2017)

Waste heat recovery (WHR) Organic Rankine Cycle (ORC) system is a very promising technology for reducing fuel consumption and consequently the CO2 emissions of future heavy-duty trucks (HDT). Nonetheless ... [more ▼]

Waste heat recovery (WHR) Organic Rankine Cycle (ORC) system is a very promising technology for reducing fuel consumption and consequently the CO2 emissions of future heavy-duty trucks (HDT). Nonetheless, the adoption of this technology in the automotive domain requires specific R&D activities going from the system definition to the on-board integration. This study focuses on the preliminary design phase of ORC systems recovering the heat wasted from two of the sources available on a HDT: the exhaust and recirculated gases. From these heat sources and their combinations, 6 possible architectures are identified. On the other hand, 4 volumetric expansion machine technologies are considered (scroll, screw, piston and vane Expanders). At the end, 24 topologies are therefore modelled considering the main components (Pump, Heat exchangers, Expansion machines). A three-step optimization method is proposed to identify the most promising system. First, the most suitable conditions are identified for the design of the ORC systems using a simple model of volumetric expansion machine. In a second step, the design phase, using more detailed models for the expansion machines, a thermos-economic optimization is performed. Finally, in a third step, the output power of the latter system models is maximized in off-design conditions, optimizing the evaporating pressure and the overheating degree. [less ▲]

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See detailProjets de Récupération de chaleur fatale suivis par l’ULg
Lemort, Vincent ULg; Le, Van Long; Gendebien, Samuel ULg et al

Conference (2017)

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See detailNonlinear identification and control of Organic Rankine Cycle systems using sparse polynomial models
Hernandez, Andres; Ruiz, Fredy; Ionescu, Clara et al

in Proceedings of the 2016 IEEE Conference on Control Applications (CCA) Part of 2016 IEEE Multi-Conference on Systems and Contro (2016, September 19)

Development of a first principles model of a system is not only a time- and cost- consuming task, but often leads to model structures which are not directly usable to design a controller using current ... [more ▼]

Development of a first principles model of a system is not only a time- and cost- consuming task, but often leads to model structures which are not directly usable to design a controller using current available methodologies. In this paper we use a sparse identification procedure to obtain a nonlinear polynomial model. Since this is a NP-hard problem, a relaxed algorithm is employed to accelerate its convergence speed. The obtained model is further used inside the nonlinear Extended Prediction Self-Adaptive control (NEPSAC) approach to Non- linear Model Predictive Control (NMPC), which replaces the complex nonlinear optimization problem by a simpler iterative quadratic programming procedure. An organic Rankine cycle system, characterized for presenting nonlinear time-varying dynamics, is used as benchmark to illustrate the effectiveness of the proposed combined strategies. [less ▲]

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See detailSteady-state and dynamic validation of a small scale waste heat recovery system using the ThermoCycle Modelica library
Desideri, Adriano ULg; Hernandez, Andres; Gusev, Sergei et al

in Energy (2016), 115

The organic Rankine cycle (ORC) power system has been recognized as a promising technology for micro power applications. In this context, physics-based dynamic models can constitute a significant tool for ... [more ▼]

The organic Rankine cycle (ORC) power system has been recognized as a promising technology for micro power applications. In this context, physics-based dynamic models can constitute a significant tool for the further development of the technology, allowing to evaluate and optimize response times during transients, or to implement and test innovative control strategies. In this contribution, the dynamic model of an ORC power unit based on the ThermoCycle Modelica library is validated against steady-state and transient experimental results from an 11 kWel stationary ORC system. The simulation results are in good agreement with the measurements, both in steady-state and in transient conditions. The validated library is readily usable to investigate demanding dynamics-based problems for low capacity power systems. [less ▲]

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See detailDYNAMIC MODELING OF WASTE HEAT RECOVERY ORGANIC RANKINE CYCLE SYSTEMS IN THE AMESIM PLATFORM
Guillaume, Ludovic ULg; Ameel, Bernd; Criens, Chris et al

Conference (2016, September 14)

ORC waste heat recovery is a very promising technology for reducing fuel consumption and consequently the CO2 emissions of future heavy-duty trucks. Because of the transient nature of the heat sources ... [more ▼]

ORC waste heat recovery is a very promising technology for reducing fuel consumption and consequently the CO2 emissions of future heavy-duty trucks. Because of the transient nature of the heat sources encountered on a truck, dynamic simulations are an essential part of the design process of ORC systems for truck applications. Dynamic models are useful for component design, control design and transient evaluation of ORC systems. To ease the burden of building numerous dynamic models of different candidate ORCs while the design process is ongoing, a library of generic dynamic models of ORCs is built in this work. These models work in synergy with a steady-state ORC design tool in which is added a function to automatically populate the parameters of the dynamic models. In this work, the dynamic model library and their parameterization process in LMS AMESim are described. The platform is largely used in automotive industry and offers a variety of libraries: Engine, Control, Two-Phase Flow, etc. Finally, the dynamic models are compared against the steady-state models and experimental data. [less ▲]

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