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Peer Reviewed
See detailDynamic Magnetic Resonance Perfusion: Influence of the Cardiac Cycle on Left Ventricle and Myocardial Signal Intensity Measurements
BROUSSAUD, T; AOUCHRIA, A; MANCINI, ISABELLE et al

Poster (2011)

Detailed reference viewed: 8 (0 ULg)
Peer Reviewed
See detailDynamic magnetic resonance perfusion: influence of the cardiac cycle on left ventricle and myocardial signal intensity measurements
BROUSSAUD; AOUCHRIA, S; MANCINI, ISABELLE et al

Poster (2011, October)

Detailed reference viewed: 8 (1 ULg)
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Peer Reviewed
See detailDynamic mechanical thermal and infrared analyses of polyacrylonitrile "electrografted" onto a metal
Calberg, Cédric ULg; Mertens, Marc; Baute, Noëlle et al

in Journal of Polymer Science. Part B, Polymer Physics (1998), 36(4), 543-553

Polyacrylonitrile (PAN) films have been grafted onto copper electrodes by cathodic polarization and analyzed by infrared spectroscopy and dynamic mechanical thermal analysis (DMTA). The dynamic mechanical ... [more ▼]

Polyacrylonitrile (PAN) films have been grafted onto copper electrodes by cathodic polarization and analyzed by infrared spectroscopy and dynamic mechanical thermal analysis (DMTA). The dynamic mechanical response shows two or three transitions depending on the film thickness and the potential deposition. The viscoelastic properties of ungrafted PAN films, e.g., solvent cast films of commercially available PAN, are deeply different from those of electrografted films. The experimental data support that ungrafted chains are paracrystalline in contrast to the grafted ones which are essentially amorphous. Moreover, the irreversible transformation of the grafted PAN chains observed beyond 225°C is confirmed by Fourier transform infrared (FTIR) analysis and ascribed to an intramolecular cyclization of PAN into polyimine. This reaction occurs rapidly and at a comparatively low temperature with respect to ungrafted PAN, which suggests that the grafted chain configuration might be predominantly isotactic. The isotacticity and the amorphous structure appear to decrease as the thickness of the PAN film is increased. Literature data and the herein reported observations would suggest a dependence of the amorphous structure of PAN on the chain isotacticity. [less ▲]

Detailed reference viewed: 47 (2 ULg)
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See detailA dynamic model of an experimental bloom of coccolithophores Emiliania huxleyi
Joassin, Pascal ULg; Borges, Alberto ULg; Chou, Lei et al

Conference (2007, November 27)

A dynamic model has been developed to represent biogeochemical events observed during an experimentally induced bloom of coccolithophores Emiliania huxleyi. This bloom occurred in a mesocosm experiment ... [more ▼]

A dynamic model has been developed to represent biogeochemical events observed during an experimentally induced bloom of coccolithophores Emiliania huxleyi. This bloom occurred in a mesocosm experiment (Bergen 2001 experiment) during which ecosystem development was followed over a 23-days period through changes of the stocks of inorganic nutrients (nitrate, ammonium and phosphate), dissolved inorganic carbon and pCO2, O2 concentration, pigments, particulate organic carbon and nitrogen, dissolved organic carbon, the production of Transparent Exopolymeric Particles (TEP), primary production, alkalinity, calcification and particulate inorganic carbon. The dynamic model is based on unbalanced algal growth and balanced growth for bacteria as described in Van den Meersche et al. (2004). In addition, in order to adequately reproduce the observations, the model has been extended by including an explicit description of calcification, T.E.P production and an enhanced mortality due to viruses. This last process, based on a critical promiscuity between cellular hosts and viral agents, successfully contributed to reproduce the bloom extinction as observed in the mesocosm experiment. This model will be implemented in a coupled physical-biogeochemical model of the Black Sea ecosystem in the framework of the EU Sesame project and in the Gulf of Biscay in the frame of the Belgian PEACE project. [less ▲]

Detailed reference viewed: 102 (3 ULg)
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See detailDynamic model reduction of a thermocline storage integrated in a micro-scale solar power plant
Wéber, Noé ULg

Master's dissertation (2015)

Concentrated solar power plants (CSPs) are one of the growing technologies that will help increase the share of renewable energy in the world’s electricity production. Coupling them with a storage tank ... [more ▼]

Concentrated solar power plants (CSPs) are one of the growing technologies that will help increase the share of renewable energy in the world’s electricity production. Coupling them with a storage tank allows for the storage of excess energy during sunny periods to be reused during the day, hence improving the plant’s capacity factor and reducing the cost of electricity. Thermocline storage tanks are a very good compromise between cost and efficiency constraints, compared with other storage technologies. Nevertheless, powerful dynamic simulation tools are needed to model efficiently the transients linked to the intermittency of the solar source. The aim of the proposed thesis is to contribute to the development of such tools. This paper first compares existing physical deterministic models of a thermocline storage tank and a parabolic trough solar field to reduced models over four reference days. The deterministic models give accurate results with high simulation times, whereas the reduces models are fast, but loose some precision in the results. Some flaws of the simplified tank model are detected, and a third model of storage system is designed. Based on the study of numerous charging and discharging processes, the law that characterizes the evolution of the thermocline is computed and integrated in the new model. This model is then validated over the same four reference days; the dynamic update of the height of the thermocline allows this new model to fit very well any weather condition. The model developed has fixed dimensions and parameters, which limits its generality. As such, a fourth model of tank is developed, based on dimensionless numbers. This last model is validated in various conditions, and is therefore suitable to any situation, with no constraint regarding weather conditions, geometry of the tank or working fluid. The simulation time required by this model is between 75 and 180 times less than that of the first complex model, and the robustness of the model is flawless, which makes it a very powerful tool. Finally, a new control strategy for the solar power plant is assessed : it allows validation of the new model of tank in yet another set of working conditions, as well as investigation of advantages and drawbacks of one strategy over an other. An unexpected observation is that the thermocline height at the end of the day does not depend on the strategy used, even though the evolution is different in both cases. Some numerical issues that have been tackled to bring the model to a perfect robustness are also discussed. [less ▲]

Detailed reference viewed: 68 (2 ULg)
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See detailDynamic Modeling and control of a pilot CO2 postcombustion capture plant
Léonard, Grégoire ULg; Cabeza Mogador, Bruno; Belletante, Ségolène et al

Poster (2013, June)

A dynamic model of a post-combustion capture pilot plant is developed using Aspen Plus Dynamics. An innovative process control strategy is studied for regulating the water balance of the process. A ... [more ▼]

A dynamic model of a post-combustion capture pilot plant is developed using Aspen Plus Dynamics. An innovative process control strategy is studied for regulating the water balance of the process. A washing section where the flue gas from the absorber is washed with cold water is included to the process in order to reduce the emissions of amine to the air. Control of the water balance in the solvent loop is successfully achieved by changing the washing water temperature. In previous publications regarding CO2 capture pilot plants, the regulation of the water balance always required a water make-up flow which appears here as unnecessary. Rejection of disturbances and different load reduction scenarios are tested to confirm the efficiency of this strategy. Potential operational problems of this control strategy are identified and solved. [less ▲]

Detailed reference viewed: 86 (4 ULg)
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See detailDynamic modeling and control strategies analysis of a novel small CSP biomass plant for cogeneration applications in building
Desideri, Adriano ULg; Amicabile, Simone; Alberti, Fabrizio et al

in Dynamic modeling and control strategies analysis of a novel small CSP biomass plant for cogeneration applications in building (2015, November 12)

A concentrated solar power (CSP) biomass combined heat and power (CHP) system based on organic Rankine cycle (ORC) technology developed in the framework of the EU founded BRICKER project is presented. The ... [more ▼]

A concentrated solar power (CSP) biomass combined heat and power (CHP) system based on organic Rankine cycle (ORC) technology developed in the framework of the EU founded BRICKER project is presented. The CHP system coupled with heat recovery ventilation technology and novel insulation material has the aim of reducing the energy consumption of existing building by up to 50%. A simplified approach to implement a dynamic model of the CHP system is proposed. The model is firstly used to investigate the performances of the CHP system control logic under extreme working condition. Secondly, the effectiveness in ensuring safe working conditions and in maximizing the sun power usage of two different solar field control approaches is investigated simulating the developed model over a reference day [less ▲]

Detailed reference viewed: 49 (4 ULg)
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See detailDynamic modeling and control strategies for Organic Rankine Cycle systems
Quoilin, Sylvain ULg; Lemort, Vincent ULg

Conference (2012, September 13)

Control and optimization are major issues in ORC systems applied to waste heat sources. This talk provides an overview of the current state of the art and of the main areas of R&D in that topic, including ... [more ▼]

Control and optimization are major issues in ORC systems applied to waste heat sources. This talk provides an overview of the current state of the art and of the main areas of R&D in that topic, including: - Steady-state and dynamic modeling of ORC cycles (simulation platforms, modeling paradigms, numerical issues) - Optimization of the working conditions for a given heat source and heat sink, and in particular of the evaporating temperature - Optimal start-up and shut-down strategies (grid synchronization, pressure overshoot, ...) - Control of the cycle under transient heat source conditions - Traditional and advanced controllers (PID, Model predictive control) The different adjustable working conditions (condensing/evaporating temperature, superheating, subcooling, working fluid flow rate) are listed with regard to the available degrees of freedom (pump/expander speed, secondary fluid flow rates and temperatures) and their optimal values are derived, depending on the target application. [less ▲]

Detailed reference viewed: 394 (12 ULg)
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Peer Reviewed
See detailDynamic modeling and control strategy analysis of a micro-scale CSP plant coupled with a thermocline system for power generation
Dickes, Rémi ULg; Desideri, Adriano ULg; Bell, Ian ULg et al

in Elimar, Frank; Philippe, Papillon (Eds.) Proceedings of the ISES EuroSun 2014 Conference (2014, September 17)

Concentrated solar power systems are characterized by strong transients and require proper control guidelines to operate efficiently. In this context, a dynamic model of a 5 kWe solar ORC system is ... [more ▼]

Concentrated solar power systems are characterized by strong transients and require proper control guidelines to operate efficiently. In this context, a dynamic model of a 5 kWe solar ORC system is developed in the Modelica language to investigate the possible advantages of coupling a concentrating solar power system with a thermocline packed-bed storage. The models of the solar field, the thermocline storage and the ORC unit are described and integrated in the open-source ThermoCycle library. A first regulation strategy is proposed and implemented into a controller unit. Results of a three-day simulation using real meteorological data are finally analyzed and discussed. [less ▲]

Detailed reference viewed: 239 (45 ULg)
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Peer Reviewed
See detailDynamic Modeling and Control System Definition for a Micro-CSP Plant Coupled with Thermal Storage Unit
Ireland, Melissa; Orosz, Matthew; Brisson, John et al

in Proceedings of TurboExpo 2014 (2014)

Organic Rankine cycle (ORC) systems are gaining ground as a means of effectively providing sustainable energy. Coupling small-scale ORCs powered by scroll expander-generators with solar thermal collectors ... [more ▼]

Organic Rankine cycle (ORC) systems are gaining ground as a means of effectively providing sustainable energy. Coupling small-scale ORCs powered by scroll expander-generators with solar thermal collectors and storage can provide combined heat and power to underserved rural communities. Simulation of such systems is instrumental in optimizing their control strategy. However, most models developed so far operate at steady-state or focus either on ORC or on storage dynamics. In this work, a model for the dynamics of the solar ORC system is developed to evaluate the impact of variable heat sources and sinks, thermal storage, and the variable loads associated with distributed generation. This model is then used to assess control schemes that adjust operating conditions for daily environmental variation. [less ▲]

Detailed reference viewed: 179 (8 ULg)
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Peer Reviewed
See detailDynamic modeling and optimal control strategy of waste heat recovery Organic Rankine Cycles
Quoilin, Sylvain ULg; Aumann, Richard; Grill, Andreas et al

in Applied Energy (2011)

Organic Rankine Cycles (ORCs) are particularly suitable for recovering energy from low-grade heat sources. This paper describes the behavior of a small scale ORC used to recover energy from a variable ... [more ▼]

Organic Rankine Cycles (ORCs) are particularly suitable for recovering energy from low-grade heat sources. This paper describes the behavior of a small scale ORC used to recover energy from a variable flow rate and temperature waste heat source. A traditional static model is unable to predict transient behavior in a cycle with a varying thermal source, whereas this capability is essential for simulating an appropriate cycle control strategy during part-load operation and start and stop procedures. A dynamic model of the ORC is therefore proposed focusing specifically on the time-varying performance of the heat exchangers, the dynamics of the other components being of minor importance. Three different control strategies are proposed and compared. The simulation results show that a model predictive control strategy based on the steady-state optimization of the cycle under various conditions is the one showing the best results. [less ▲]

Detailed reference viewed: 430 (36 ULg)
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Peer Reviewed
See detailDynamic Modeling and Validation of Radiant Ceiling Systems Coupled to its Environment
Fonseca, Néstor; Cuevas, Cristian; Lemort, Vincent ULg

(2010, July)

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal ... [more ▼]

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation system). The model considers the radiant panels as a dynamic-state finned heat exchanger connected to a detailed lumped dynamic model of the building (R-C network). The behavior of the radiant ceiling system and the interactions with its environment has been experimentally and numerically evaluated. Using as inputs the radiant ceiling and room dimensions, material properties and the transient measurements of air temperature at the adjacent zones, supply air and water temperatures and mass flow rates, the model allows for the estimation of the water exhaust temperature, radiant ceiling average surface temperature, resultant and dry air room temperatures, radiant ceiling power and internal surface temperatures of the room in order to compare with measurements taken during the commissioning process. Two dynamic tests in heating and cooling modes are used to validate the model. [less ▲]

Detailed reference viewed: 53 (7 ULg)
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Peer Reviewed
See detailDynamic modeling of methylotrophic Pichia pastoris culture with exhaust gas analysis: from cellular metabolism to process simulation
Niu, H; Daukandt, M; Rodriguez, Ch et al

in Chemical Engineering Science (2013), (87), 381-392

Detailed reference viewed: 10 (1 ULg)
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See detailDynamic Modeling of Organic Rankine Cycle Power Systems
Desideri, Adriano ULg

Doctoral thesis (2016)

Detailed reference viewed: 41 (6 ULg)
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Peer Reviewed
See detailDynamic modeling of thermal systems using a semi-empirical approach and the ThermoCycle Modelica Library
Altés Buch, Queralt ULg; Dickes, Rémi ULg; Desideri, Adriano ULg et al

in Proceedings of the 28th International Conference on Efficiency, Costs, Optimization and Simulation of Energy Systems (2015, June)

This paper proposes an innovative approach for the dynamic modeling of heat exchangers without phase transitions. The proposed thermo-flow model is an alternative to the traditional 1D finite-volumes ... [more ▼]

This paper proposes an innovative approach for the dynamic modeling of heat exchangers without phase transitions. The proposed thermo-flow model is an alternative to the traditional 1D finite-volumes approach and relies on a lumped thermal mass approach to model transient responses. The heat transfer is modeled by the well-known Logarithmic Mean Temperature Difference approach, which is modified to ensure robustness during all possible transient conditions. The lumped parameter models are validated with references models and tested within a Concentrating Solar Power plant model. Results indicate that the developed lumped models are robust and computationally efficient, ensuring the convergence of the Newton Solver. They are significantly faster (~10-fold) than the traditional finite volume models, although a more extensive comparisons would be needed to confirm this figure. They are well suited to be integrated in larger system models, but are not appropriate for the simulation of detailed thermo-flow phenomena. [less ▲]

Detailed reference viewed: 188 (21 ULg)
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Peer Reviewed
See detailDYNAMIC MODELING OF WASTE HEAT RECOVERY ORGANIC RANKINE CYCLE SYSTEMS IN THE AMESIM PLATFROM
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 ▲]

Detailed reference viewed: 99 (4 ULg)
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See detailDynamic modelling and control of a pilot plant for post-combustion CO2 capture
Léonard, Grégoire ULg; Cabeza Mogador, Bruno; Belletante, Ségolène et al

in Computer Aided Chemical Engineering (2013), 31

A dynamic model of a post-combustion pilot capture plant is developed using Aspen Plus Dynamics. An innovative process control strategy is studied for regulating the water balance of the process. A ... [more ▼]

A dynamic model of a post-combustion pilot capture plant is developed using Aspen Plus Dynamics. An innovative process control strategy is studied for regulating the water balance of the process. A washing section where the flue gas from the absorber is washed with cold water is included to the process in order to reduce the emissions of amine to the air. Control of the water balance in the solvent loop is successfully achieved by changing the washing water temperature. In previous publications regarding CO2 capture pilot plants, the regulation of the water balance always required a water make-up flow which appears here as unnecessary. Rejection of disturbances and different load reduction scenarios are tested to confirm the efficiency of this strategy. Potential operational problems of this control strategy are identified and solved. [less ▲]

Detailed reference viewed: 229 (23 ULg)
See detailDynamic Modelling, Simulation Analysis---Useful for Understanding Biology?
Bullinger, Eric ULg

Scientific conference (2005, November 11)

Detailed reference viewed: 6 (0 ULg)
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Peer Reviewed
See detailDynamic MR Based Analysis of Tumor Movement in Upper and Mid Lobe Localized Lung Cancer
Kovacs; Hadjiev; LAKOSI, Ferenc ULg et al

in Pathology Oncology Research (2008)

Detailed reference viewed: 6 (0 ULg)