References of "Lemort, Vincent"
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See detailOrganic Rankine Cycles including fluid selection
Lemort, Vincent ULg; Declaye, Sébastien ULg; Quoilin, Sylvain ULg

in Handbook of Clean Energy Systems (in press)

An Organic Rankine Cycle (ORC) is similar to a steam Rankine cycle, except that the working fluid is not water but an organic compound, such as a refrigerant or a hydrocarbon, characterized by a lower ... [more ▼]

An Organic Rankine Cycle (ORC) is similar to a steam Rankine cycle, except that the working fluid is not water but an organic compound, such as a refrigerant or a hydrocarbon, characterized by a lower ebullition temperature than that of water. Hence lower temperature heat sources can be exploited such as solar energy, geothermal energy and waste heat recovery from many different processes. During the design phase of an ORC system, the selection of the working fluid must be conducted in parallel with the selection and the sizing of the components (mainly the expansion machine, the pump and the heat exchangers) and with the definition of the cycle architecture. This approach allows taking into consideration all technical constraints. Relevant properties of working fluids that should be considered during their selection are listed. Major characteristics of available displacement and turbo-expander technologies are described. The impact of the pump performance on the overall performance is discussed and strategies to increase the available NPSH are proposed. Finally, improved cycle architectures are introduced. Major applications of ORC systems are described: geothermal power plants, biomass CHP plants, waste heat recovery in industry, waste heat recovery on internal combustion engines and solar power plants. All these applications differ by the nature of the heat source and heat sink, the integration of the ORC with these sources and sinks, and the range of installed capacities. These differences yield specific designs, which are described. Performance achieved by systems in operation or prototypes are presented. [less ▲]

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See detailDirect control service from residential heat pump aggregation with specified payback
Georges, Emeline ULg; Cornélusse, Bertrand ULg; Ernst, Damien ULg et al

in Proceedings of the 19th Power Systems Computation Conference (PSCC) (2016, June)

This paper addresses the problem of an aggregator controlling residential heat pumps to offer a direct control flexibility service. The service is defined by a 15 minute power modulation, upward or ... [more ▼]

This paper addresses the problem of an aggregator controlling residential heat pumps to offer a direct control flexibility service. The service is defined by a 15 minute power modulation, upward or downward, followed by a payback of one hour and 15 minutes. The service modulation is relative to an optimized baseline that minimizes the energy costs. The potential amount of modulable power and the payback effect are computed by solving mixed integer linear problems. Within these problems, the building thermal behavior is modeled by an equivalent thermal network made of resistances and lumped capacitances whose parameters are identified from validated models. Simulations are performed on 100 freestanding houses. For an average 4.3 kW heat pump, results show a potential of 1.2 kW upward modulation with a payback of 600 Wh and 150 Wh of overconsumption. A downward modulation of 500 W per house can be achieved with a payback of 420 Wh and 120 Wh of overconsumption. [less ▲]

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See detailPerformance of a radial-inflow turbine integrated in an ORC system and designed for a WHR on truck application: An experimental comparison between R245fa and R1233zd
Guillaume, Ludovic ULg; Legros, Arnaud ULg; Desideri, Adriano ULg et al

in Applied Energy (2016)

The goal of this study is to experimentally compare the performance of an Organic Rankine Cycle (ORC) system equipped with a radial-inflow turbine for two working fluids: R245fa and R1233zd. The radial ... [more ▼]

The goal of this study is to experimentally compare the performance of an Organic Rankine Cycle (ORC) system equipped with a radial-inflow turbine for two working fluids: R245fa and R1233zd. The radial- inflow turbine is a small-scale prototype designed to convert the waste heat from the exhaust gases of a truck combustion engine and was developed mainly using components of truck turbochargers. It is directly connected to a high-speed synchronous generator. The bearings system of the turbine and the generator have the innovative particularity to be respectively lubricated and cooled down by the working fluid so no additional lubricant or coolant is needed. The experimental comparison is carried out over a test-rig equipped with the radial turbine. The heat wasted by the truck through the exhaust gases is sim- ulated using an electric oil boiler coupled to the ORC loop. The electrical power supplied by the turbine, limited to a maximum of 3.5 kWel by the generator, is then dissipated in a load bank composed of truck fans while the condenser is cooled by a water loop. Measurements in steady-state are performed in order to evaluate the performance of the turbine-generator set when varying the pressure ratio, the rotational speed, the inlet temperature and the mass flow rate of the turbine and the lubrication flow rate of the bearings for various oil temperatures and mass flow rates. In order to identify the most suitable fluid for the Waste Heat Recovery (WHR) application, three comparison methods are proposed and discussed based on the measurements. Finally, because the turbine-generator set is the first oil-free prototype developed by the manufacturer, potential sources of improvements are discovered and discussed. [less ▲]

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See detailExperimental comparison of organic fluids for low temperature ORC (organic Rankine cycle) systems for waste heat recovery applications
Desideri, Adriano ULg; Gusev, Sergei; Van den Broek, Martijn et al

in Energy (2016), 97

This contribution experimentally evaluates and compares the performance of an ORC (organic Rankine cycle) system for stationary bottoming WHR (waste heat recovery) application operating with two different ... [more ▼]

This contribution experimentally evaluates and compares the performance of an ORC (organic Rankine cycle) system for stationary bottoming WHR (waste heat recovery) application operating with two different working fluids, SES36 and R245fa. The test rig is a regenerative cycle equipped with a single screw expander modified from a standard compressor characterized by a nominal shaft power of 11 kW. A total of 36 and 43 steady-state points are collected for SES36 and R245fa respectively, over a wide range of operating conditions by changing the expander rotational speed, the pump frequency and the cooling condenser flow rate. The performances of the ORC components are individually evaluated. A maximum expander isentropic efficiency of 60% is reached using SES36 at 3000 rpm, and a value of 52% is reached with R245fa at 3000 rpm. However, for a given pressure ratio the expander output power is higher with R245fa than with SES36. The overall performance of the ORC unit are investigated in terms of first and second law efficiencies and net output power for the two fluids. The results experimentally demonstrate the correlation between the working fluid critical temperature and the ORC unit working characteristics for low temperature waste heat recovery applications. Open experimental data are provided for both fluids. [less ▲]

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See detailNoWaste: waste heat re-use for greener truck
Bettoja, Federica; Perosino, Andrea; Lemort, Vincent ULg et al

in Proceedings of 6th Transport Research Arena (2016)

The present paper summarizes the key points of the European NoWaste Project, which aims at developing Rankine cycle systems for integration into long-haul trucks with the aim to convert the waste heat of ... [more ▼]

The present paper summarizes the key points of the European NoWaste Project, which aims at developing Rankine cycle systems for integration into long-haul trucks with the aim to convert the waste heat of the exhaust gases into useful energy usable in mechanical or electrical form. The first part of the paper describes the ORC system architectures defined for two different truck engines: one with EGR and the other one without EGR. For both engines, different cycle configurations and working fluids are compared in terms of energy performance and technical constraints. For both ORC systems, the paper shows the final technical choices made in terms of main components: boiler, condenser, expander and pump. The second part of the paper presents preliminary experimental results carried out on demonstrators of the two ORC systems. The objectives of these tests were to check the performance announced by the components’ manufacturers. Finally, the last part of the paper compares the cost of both systems. [less ▲]

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See detailReal-Time Optimization of Organic Rankine Cycle Systems by Extremum-Seeking Control
Hernandez Naranjo, Jairo Andres ULg; Desideri, Adriano ULg; Ionescu, Clara et al

in Energies (2016), 9

In this paper, the optimal operation of a stationary sub-critical 11kWel organic Rankine cycle (ORC) unit for waste heat recovery (WHR) applications is investigated, both in terms of energy production and ... [more ▼]

In this paper, the optimal operation of a stationary sub-critical 11kWel organic Rankine cycle (ORC) unit for waste heat recovery (WHR) applications is investigated, both in terms of energy production and safety conditions. Simulation results of a validated dynamic model of the ORC power unit are used to derive a correlation for the evaporating temperature, which maximizes the power generation for a range of operating conditions. This idea is further extended using a perturbation-based extremum seeking (ES) algorithm to identify online the optimal evaporating temperature. 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 for state estimators, making it a suitable tool for industrial applications. 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 detailComparison of Moving Boundary and Finite-Volume Heat Exchanger Models in the Modelica Language
Desideri, Adriano ULg; Dechesne, Bertrand ULg; Wronski, Jorrit et al

in energies (2016)

When modeling low capacity energy systems, such as a small size (5–150kWel) organic Rankine cycle unit, the governing dynamics are mainly concentrated in the heat exchangers. As a consequence, the ... [more ▼]

When modeling low capacity energy systems, such as a small size (5–150kWel) organic Rankine cycle unit, the governing dynamics are mainly concentrated in the heat exchangers. As a consequence, the accuracy and simulation speed of the higher level system model mainly depend on the heat exchanger model formulation. In particular, the modeling of thermo-flow systems characterized by evaporation or condensation requires heat exchanger models capable of handling phase transitions. To this aim, the finite volume (FV) and the moving boundary (MB) approaches are the most widely used. The two models are developed and included in the open-source ThermoCycle Modelica library. In this contribution, a comparison between the two approaches is presented. An integrity and accuracy test is designed to evaluate the performance of the FV and MB models during transient conditions. In order to analyze how the two modeling approaches perform when integrated at a system level, two organic Rankine cycle (ORC) system models are built using the FV and the MB evaporator model, and their responses are compared against experimental data collected on an 11kWel ORC power unit. Additionally, the effect of the void fraction value in the MB evaporator model and of the number of control volumes (CVs) in the FV one is investigated. The results allow drawing general guidelines for the development of heat exchanger dynamic models involving two-phase flows. [less ▲]

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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 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 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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