References of "Lemort, Vincent"
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See detailTransient performance evaluation of waste heat recovery Rankine cycle based system for heavy duty trucks
Grelet, Vincent; Reiche, Thomas; Lemort, Vincent ULg et al

in Applied Energy (2016)

The study presented in this paper aims to evaluate the transient performance of a waste heat recovery Rankine cycle based system for a heavy duty truck and compare it to steady state evaluation. Assuming ... [more ▼]

The study presented in this paper aims to evaluate the transient performance of a waste heat recovery Rankine cycle based system for a heavy duty truck and compare it to steady state evaluation. Assuming some conditions to hold, simple thermodynamic simulations are carried out for the comparison of several fluids. Then a detailed rst principle based model is also presented. Last part is focused on the Rankine cycle arrangement choice by means of model based evaluation of fuel economy for each concept where the fuels savings are computed using two methodologies. Fluid choice and concept optimization are conducted taking into account integration constraints (heat rejection, packaging . . . ). This paper shows the importance of the modeling phase when designing WHRS and yields a better understanding when it comes to a vehicle integration of a Rankine cycle in a truck. [less ▲]

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See detailTechno-economic optimization of isolate micro-grids including PV and Li-Ion Batteries in the Bolivian context
Balderrama, Sergio; Canedo, Walter; Lemort, Vincent ULg et al

in Proceedings of ECOS 2016 - the 29th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (2016)

In Bolivia 44 % of the people living in rural areas do not have reliable access to electric energy. This is due to a combination of unfavourable geography and the lack of economic resources to achieve the ... [more ▼]

In Bolivia 44 % of the people living in rural areas do not have reliable access to electric energy. This is due to a combination of unfavourable geography and the lack of economic resources to achieve the necessary infrastructure. In this context, the main goal of this study is to evaluate the economic and technical feasibility of micro-grids including photovoltaic panels (PV), batteries systems and the possible inclusion of diesel generators for off-grid applications. To that aim, a linear optimization model was developed within the Pyomo framework in order to optimize both the installed capacities and dispatch of the PV, battery and diesel sub-systems. The defined objective function is the net present cost. The exogenous inputs of the optimization are the typical demand and solar irradiation of a region of Bolivia in order to achieve results close to real Bolivian systems. Results indicate that due to the high levels of subvention to hydrocarbons, the PV and Li-Ion technology are not yet competitive with a diesel generator for the electrification of rural areas. On the other hand a sensitivity analysis is performed and proves that if the government decide to stop part of the subvention or shared it between conventional and non-conventional sources, the PV becomes competitive and the Li-Ion batteries enter the market around 2020. [less ▲]

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See detailEconomic assessment of energy storage for load shifting in Positive Energy Building
Dumont, Olivier ULg; Carmo, carolina; Georges, Emeline ULg et al

Conference (2016)

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See detailOrganic Rankine cycles systems for waste heat recovery in marine applications
Bellolio Domke, Sebastian Andres ULg; Lemort, Vincent ULg; Rigo, Philippe ULg

Scientific conference (2015, November 26)

In marine applications powered by internal combustion engines, a considerable amount of the energy contained in fuel is wasted through thermal losses. Additionally, as the years go by, new and more severe ... [more ▼]

In marine applications powered by internal combustion engines, a considerable amount of the energy contained in fuel is wasted through thermal losses. Additionally, as the years go by, new and more severe standards and regulations are imposed to the maritime industry. Despite of the traditional use of the waste heat recovery systems in ships, in order to meet new emissions demands, the research towards less traditional ways to reduce vessels emissions has been pushed. Nowadays the use of Organic Rankine cycles (ORC) seems to be a very promising solution to increase the global efficiency in maritime applications by converting the vessel’s thermal losses into useful work. Even if ORC’s have been studied during the last decades, it is only in the recent years that the maritime industry has drawn its attention towards these systems. In the first part of this paper, a state of the art of ORC in marine applications is performed. Then, the use of an ORC over traditional waste heat recovery methods (steam Rankine cycles) used in ships is discussed. Finally, a thermodynamic steady-state model of an ORC is coupled to a vessel ICE to estimate the improvements in energy efficiency that could be achieved by implementing an ORC in a vessel. [less ▲]

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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 ▲]

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See detailGlobal optimization of the production and the distribution system for typical European HVAC systems
Randaxhe, François ULg; Lemort, Vincent ULg; Lebrun, Jean ULg

in Energy Procedia (2015), 78

European countries have agreed on a new 2030 Framework with a 30% improvement in energy efficiency compared to projection and a 40% cut in greenhouse gas emissions compared to 1990 levels. With an ... [more ▼]

European countries have agreed on a new 2030 Framework with a 30% improvement in energy efficiency compared to projection and a 40% cut in greenhouse gas emissions compared to 1990 levels. With an estimated 11% of all the electrical energy used in Europe consumed by HVAC systems, the improvement of their efficiency is a key element to reach these targets. When looking at the energy flow in typical European HVAC systems, one can observe important degradation in efficiency associated to heating and cooling energy transportation systems together with a non-optimal use of the production plant. These inefficiencies are direct consequences of the system design with, quite often, a lack of consideration of the system part load or its off-design operation. This research attempts to identify the sensitivity of both cooling and heating HVAC systems to these conditions and to propose an approach to optimize the design and the operation of HVAC systems integrated in buildings considering trade-off between primary systems efficiency, distribution losses and auxiliaries consumption. [less ▲]

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See detailImpact of model reduction on the dynamic simulation of a micro-scale concentrated solar power system integrated with a thermal storage
Dickes, Rémi ULg; Wéber, Noé ULg; Lemort, Vincent ULg et al

in Proceedings of the ISES Solar World Congress 2015 (2015, November)

Because of the intermittent nature of solar irradiances, micro-scale solar thermal power systems almost never operate in nominal operating conditions. They are characterized by strong transients and ... [more ▼]

Because of the intermittent nature of solar irradiances, micro-scale solar thermal power systems almost never operate in nominal operating conditions. They are characterized by strong transients and require robust, fast and accurate dynamic simulation tools to permit a proper evaluation of their performance. Model reduction, i.e. the simplification of detailed models, is an attractive method to improve the computational efficiency while simulating such systems. In this context, a µCSP plant featuring a solar field of parabolic troughs, a thermocline storage and a 5kWe power unit is investigated. Both the solar field and the thermocline storage are modeled with complex and simplified methods. The whole power plant is simulated under identical operating condition and deviations between the simulation results are analyzed. Benefits and limitations of the current modeling approach are assessed. Improvements for the modeling of the thermocline storage are identified, implemented and validated. The Modelica language is used as simulation tool and the models developed in this work are integrated in the open-source ThermoCycle library. [less ▲]

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See detailTOWARDS THE OPTIMAL OPERATION OF AN ORGANIC RANKINE CYCLE UNIT BY MEANS OF MODEL PREDICTIVE CONTROL Andres
Hernandez Naranjo, Jairo Andres ULg; Desideri, Adriano ULg; Ionescu, Clara et al

in TOWARDS THE OPTIMAL OPERATION OF AN ORGANIC RANKINE CYCLE UNIT BY MEANS OF MODEL PREDICTIVE CONTROL (2015, October 14)

In this paper the optimal operation of an Organic Rankine Cycle (ORC) unit is investigated both in terms of energy production and safety conditions. Simulations on a validated dynamic model of a real re ... [more ▼]

In this paper the optimal operation of an Organic Rankine Cycle (ORC) unit is investigated both in terms of energy production and safety conditions. Simulations on a validated dynamic model of a real re- generative ORC unit, are used to illustrate the existence of an optimal evaporating temperature which maximizes energy production for some given heat source conditions. This idea is further extended using a perturbation based Extremum Seeking (ES) algorithm to find online the optimal evaporating tempera- ture. Regarding safety conditions we propose the use of the Extended Prediction Self-Adaptive Control (EPSAC) approach to constrained Model Predictive Control (MPC). Since it uses input/output models for prediction, it avoids the need of state estimators, making of it a suitable tool for industrial applica- tions. The performance of the proposed control strategy is compared to PID-like schemes. Results show that EPSAC-MPC is a more effective control strategy as it allows a safer and more efficient operation of the ORC unit, as it can handle constraints in a natural way, operating close to the boundary conditions where power generation is maximized. [less ▲]

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See detailAnalysis and comparison of different modeling approaches for the simulation of a micro-scale organic Rankine cycle power plant
Dickes, Rémi ULg; Dumont, Olivier ULg; Legros, Arnaud ULg et al

in Proceedings of the 3rd International Seminar on ORC Power Systems (2015, October 12)

When simulating a system based on the organic Rankine cycle (ORC), different modeling methods can be used to predict its performance. Each method is characterized by advantages, limitations and a level of ... [more ▼]

When simulating a system based on the organic Rankine cycle (ORC), different modeling methods can be used to predict its performance. Each method is characterized by advantages, limitations and a level of complexity. This contribution aims to assess the impact of the modeling approach on the performance prediction of ORC systems. To this end, a 2.8 kWe ORC unit is investigated as case study. In this paper, the components of the test bench are modeled using different approaches of increasing complexity and each model is calibrated using experimental data from the test rig. The goodness of fit as well as the benefits and limitations of each modeling methods are analyzed and discussed. [less ▲]

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See detailPerformances of a simple exhaust mechanical ventilation coupled to a mini heat pump: modeling and experimental investigations
Ransy, Frédéric ULg; Gendebien, Samuel ULg; Lemort, Vincent ULg

Conference (2015, September 24)

According to the European directive 2012/27/EU of October 2012 on energy efficiency, buildings represented 40 % of the EU’s final energy consumption in 2011. The major part of this energy consumption is ... [more ▼]

According to the European directive 2012/27/EU of October 2012 on energy efficiency, buildings represented 40 % of the EU’s final energy consumption in 2011. The major part of this energy consumption is due to the residential sector for space heating and domestic hot water production. Moreover, buildings are crucial to achieve the EU objective of reducing greenhouse gas emissions by 80-95 % by 2050 compared to 1990. In order to reduce these greenhouse gas emissions, retrofit measures regarding insulation and air-tightness have to be taken. However, such improvements of the building envelope lead to a relative increase in consumption related to ventilation. Indeed, according to Orme (2001), Roulet et al. (2001) and Fouih et al. (2012), the heating demand due to ventilation can reach more than 50 % of the total building heating demand for new and retrofitted buildings. To reduce the energy consumption due to ventilation, exhaust air heat pumps (EAHPs) can be used instead of the traditional heat recovery with an air-to-air heat exchanger. EAHPs recover heat from the exhaust air of the ventilation system to produce domestic hot water and space heating. According to Fehrm et al. (2002), this technology is already widely used in the northern countries such as Germany and Sweden. In fact, according to Fracastoro et al. (2010), efficiencies of EAHPs are higher than those obtained with outside air or geothermal heat pumps in certain conditions, whatever the climate location. Berg et al. (2010) have monitored three houses in Sweden equiped with exhaust air heat pumps. The seasonal performance factor (SPF) values were all within the range 1.4-1.7. This factor takes into account the energy consumption of the heat pumps and the auxiliary heating systems. A 17 kW exhaust air heat pump has also been tested by Mikola et al. (2014). The measured SPF for the heat pump only (without taking into account the auxiliary heating system) was about 2.9-3.4 in winter and 3 in the summer. Exhaust air heat pumps coupled with simple exhaust mechanical ventilation systems have many advantages compared to traditional balanced systems with heat recovery: • Only one fan is necessary and the duct system is simpler. Consequently, EAHPs are suitable for retrofitted buildings. • The heat pump can provide the whole part of the heating demand related to domestic hot water and 50 % of the heating demand related to space heating, according to Fracastoro et al. (2010). • The heat pump can also provide active cooling by inversing the refrigerating cycle. • The heat pump performance is high and remains constant with outdoor temperature changes since the temperature of the heat sink is constant (20°C). As a result, the system is cost-effective. • The system is compact, quiet and requires little maintenance. In the present paper, the energetic performances of an exhaust air heat pump are assessed through numerical and experimental studies. The thermal capacity of the machine is 1.5 kW when the inside air temperature is 20°C and the outside water temperature is 35°C. The heat pump is therefore ideally suited for new or retrofitted buildings. The system including a mechanical exhaust ventilation system and an exhaust air heat pump is first presented. Secondly, the heat pump model used afterwards to determine the heat pump seasonal performance factor is described. Thirdly, the model is calibrated to fit the measurement data. Finally, the heat pump model is coupled to a building model to determine the annual performance of the system. The system is compared to a traditional balanced ventilation system with heat recovery in terms of primary energy consumption, for different heating and DHW production systems (electric heater, heat pump, gas condensing boiler). [less ▲]

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See detailLow-order models of a single-screw expander for organic Rankine cycle applications
Ziviani, Davide; Desideri, Adriano ULg; Lemort, Vincent ULg et al

in Low-order models of a single-screw expander for organic Rankine cycle applications D. (2015, September 10)

Screw-type volumetric expanders have been demonstrated to be a suitable technology for organic Rankine cycle (ORC) systems because of higher overall effectiveness and good part-load behaviour over other ... [more ▼]

Screw-type volumetric expanders have been demonstrated to be a suitable technology for organic Rankine cycle (ORC) systems because of higher overall effectiveness and good part-load behaviour over other positive displacement machines. An 11 kWe single-screw expander (SSE) adapted from an air compressor has been tested in an ORC test-rig operating with R245fa as working fluid. A total of 60 steady-steady points have been obtained at four different rotational speeds of the expander in the range between 2000 rpm and 3300 rpm. The maximum electrical power output and overall isentropic effectiveness measured were 7.3 kW and 51.9%, respectively. In this paper, a comparison between two low-order models is proposed in terms of accuracy of the predictions, the robustness of the model and the computational time. The first model is the Pacejka equation-based model and the second is a semi-empirical model derived from a well-known scroll expander model and modified to include the geometric aspects of a single screw expander. The models have been calibrated with the available steady-state measurement points by identifying the proper parameters. 1. [less ▲]

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See detailSmart Grid Energy Flexible Buildings through the use of Heat Pumps and Building Thermal Mass as Energy Storage in the Belgian context
Masy, Gabrielle; Georges, Emeline ULg; Verhelst, Clara et al

in Science and Technology for the Built Environment (2015), 21(6), 800-811

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See detailDesign, Modeling, and Performance Optimization of a Reversible Heat Pump/Organic Rankine Cycle System for Domestic Application
Quoilin, Sylvain ULg; Dumont, Olivier ULg; Harley Hansen, Kristian et al

in Journal of Engineering for Gas Turbines and Power (2015)

In this paper, an innovative system combining a heat pump (HP) and an organic Rankine cycle (ORC) process is proposed. This system is integrated with a solar roof, which is used as a thermal source to ... [more ▼]

In this paper, an innovative system combining a heat pump (HP) and an organic Rankine cycle (ORC) process is proposed. This system is integrated with a solar roof, which is used as a thermal source to provide heat in winter months (HP mode) and electricity in summer months (ORC mode) when an excess irradiation is available on the solar roof. The main advantage of the proposed unit is its similarity with a traditional HP: the HP/ORC unit only requires the addition of a pump and four-way valves compared to a simple HP, which can be achieved at a low cost. A methodology for the optimal sizing and design of the system is proposed, based on the optimization of both continuous parameters such as heat exchanger size or discrete variables such as working fluid. The methodology is based on yearly simulations, aimed at optimizing the system performance (the net yearly power generation) over its whole operating range instead of just nominal sizing operating conditions. The simulations allow evaluating the amount of thermal energy and electricity generated throughout the year, yielding a net electric power output of 3496 kWh throughout the year. [less ▲]

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See detailExperimental study of Predictive Control strategies for optimal operation of Organic Rankine Cycle systems
Hernandez Naranjo, Jairo Andres ULg; Desideri, Adriano ULg; Ionescu, Clara et al

in Experimental study of Predictive Control strategies for optimal operation of Organic Rankine Cycle systems (2015, July 17)

In this paper the performance of Model Predictive Control (MPC) and PID based strategies to optimally recover waste heat using Organic Rankine Cycle (ORC) technology is investigated. First the ... [more ▼]

In this paper the performance of Model Predictive Control (MPC) and PID based strategies to optimally recover waste heat using Organic Rankine Cycle (ORC) technology is investigated. First the relationship between the evaporating temperature and the output power is experimentally evaluated, concluding that for some given heat source conditions there exists an optimal evaporating temperature which maximizes the energy production. Three different control strategies MPC and PID based are developed in order not only to maximize energy production but to ensure safety conditions in the machine. For the case of the MPC, the Extended Prediction Self-Adaptive Control (EPSAC) algorithm is considered in this study as it uses input/output models for prediction, avoiding the need of state estimators, making of it a suitable tool for industrial applications. The experimental results obtained on a 11kWe pilot plant show that the constrained EPSAC-MPC outperforms PID based strategies, as it allows to accurately regulate the evaporating temperature with a lower control effort while keeping the superheating in a safer operating range. [less ▲]

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See detailModel reduction for simulating the dynamic behavior of parabolic troughs and a thermocline energy storage in a micro-solar power unit
Dickes, Rémi ULg; Desideri, Adriano ULg; Lemort, Vincent ULg et al

in Proceedings of ECOS 2015 (2015, July)

Micro-scale concentrated solar power plants are characterized by strong transients and mostly operate in off-design working conditions. Both the sizing and the control of these systems are key challenges ... [more ▼]

Micro-scale concentrated solar power plants are characterized by strong transients and mostly operate in off-design working conditions. Both the sizing and the control of these systems are key challenges whose optimization requires powerful dynamic modeling tools. In this context, a system featuring a solar field of parabolic troughs, a thermocline thermal energy storage and a 5kWe organic Rankine cycle (ORC) power unit is modeled in the Modelica language. Model reduction methods applied to the solar field and the thermal storage are investigated and analyzed to improve the computational efficiency of the problem. Each model is described and integrated in the open-source ThermoCycle library. Results of simulation under identical operating conditions are compared and the benefits and limitations of model reduction are assessed. [less ▲]

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See detailSemi-empirical correlation to model heat losses along solar parabolic trough collectors
Dickes, Rémi ULg; Lemort, Vincent ULg; Quoilin, Sylvain ULg

in Proceedings of ECOS 2015 (2015, July)

Solar thermal power plants convert sunshine energy into useful heat and electricity by means of solar collectors and a thermodynamic cycle. Among the different solar collector technologies, parabolic ... [more ▼]

Solar thermal power plants convert sunshine energy into useful heat and electricity by means of solar collectors and a thermodynamic cycle. Among the different solar collector technologies, parabolic troughs are nowadays the most widespread together with solar towers. In order to improve the computation speed required to simulate the temperature profile along solar parabolic trough collectors, a correlation estimating the effective heat losses of the receiver is an essential tool. However, the relations found in the literature lack accuracy and do not translate effectively the effects of the operating conditions in all cases. In this work, an alternative correlation is proposed and calibrated with the results of a deterministic model. Better fitting performance is demonstrated when compared to the prediction of the pre-existing correlations. The benefits and limitations of the new correlation are finally assessed. [less ▲]

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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 ▲]

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See detailImportance of the reconciliation method to handle experimental data: application to a reversible heat pump / organic Rankine cycle unit integrated in a positive energy building
Dumont, Olivier ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

Conference (2015, June)

Experimental data is often the result of long and costly experimentations. Many times, measurements are used directly without (or with few) analysis and treatment. This paper therefore presents a detailed ... [more ▼]

Experimental data is often the result of long and costly experimentations. Many times, measurements are used directly without (or with few) analysis and treatment. This paper therefore presents a detailed methodology to use steady-state measurements efficiently in the analysis of a thermodynamic cycle. The reconciliation method allows to correct each measurement as little as possible, taking its accuracy into account, in order to satisfy all constraints and to evaluate the most probable physical state. The reconciliation method should be used for multiple reasons. First, this method allows to close energy and mass balances exactly, which is needed for predictive models. Also, it allows determining some unknowns that are not or that cannot be measured precisely. Furthermore, it fully exploits the collected measurements with redundancy and it allows to know which sensor should be checked or replaced if necessary. An application of this method is presented in the case of a reversible HP/ORC unit. This unit is a modified heat pump which is able to work as an organic Rankine cycle by reversing its cycle. Combined with a passive house comprising a solar roof and a ground heat exchanger, it allows to get a plus energy house. In this study case, the oil mass fraction is not measured despite of its strong influence on the results. The reconciliation method allows to evaluate it. The efficiency of this method is proven by comparing the error on the outputs of steady-state models of compressor and exchangers. An example is given with the prediction of the pinch-point of an evaporator. In this case, the normalized root mean square deviation (NRMSD) is decreased from 14.3 % to 4.1 % when using the reconciliation method. This paper proves the efficiency of the method and also that the method should be considered more often when dealing with experimentation. [less ▲]

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