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See detailSystematic optimization of subcritical and transcritical organic Rankine cycles (ORCs) constrained by technical parameters in multiple applications
Maraver, Daniel; Royo, Javier; Lemort, Vincent ULg et al

in Applied Energy (2014), 117

The present work is focused on the thermodynamic optimization of organic Rankine cycles (ORCs) for power generation and CHP from different average heat source profiles (waste heat recovery, thermal oil ... [more ▼]

The present work is focused on the thermodynamic optimization of organic Rankine cycles (ORCs) for power generation and CHP from different average heat source profiles (waste heat recovery, thermal oil for cogeneration and geothermal). The general goal is to provide optimization guidelines for a wide range of operating conditions, for subcritical and transcritical, regenerative and non-regenerative cycles. A parameter assessment of the main equipment in the cycle (expander, heat exchangers and feed pump) was also carried out. An optimization model of the ORC (available as an electronic annex) is proposed to predict the best cycle performance (subcritical or transcritical), in terms of its exergy efficiency, with different working fluids. The working fluids considered are those most commonly used in commercial ORC units (R134a, R245fa, Solkatherm, n-Pentane, Octamethyltrisiloxane and Toluene). The optimal working fluid and operating conditions from a purely thermodynamic approach are limited by the technological constraints of the expander, the heat exchangers and the feed pump. Hence, a complementary assessment of both approaches is more adequate to obtain some preliminary design guidelines for ORC units. [less ▲]

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See detailDesign, modelling, performance optimization and experimentation of a reversible HP/ORC prototype.
Dumont, Olivier ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

Conference (2014)

This paper presents an innovative system comprising a water/water heat pump connected to a solar roof and a geothermal heat exchanger. This unit is able to invert its cycle and operate as an Organic ... [more ▼]

This paper presents an innovative system comprising a water/water heat pump connected to a solar roof and a geothermal heat exchanger. This unit is able to invert its cycle and operate as an Organic Rankine Cycle. The solar roof is producing a large amount of heat throughout the year. This allows covering the building annual heating needs and furthermore, electricity is produced thanks to the surplus of heat in a so-called HP/ORC reversible unit. This paper is focusing on these three main points: modeling, design and experimentation of the prototype. This paper demonstrates the feasibility of such a prototype with encouraging performance in ORC and HP modes. First simulations of the HP/ORC system, with components optimally sized, indicate that, in ORC mode, for the weather conditions of Copenhagen, the electrical energy produced over one year reaches 4030 kWh and the nominal efficiency of the cycle is 7.6%. The nominal COP of the heat pump is 4.2 (condenser exhaust temperature of 60°C and evaporator supply temperature of 15°C). Experimentally, a COP of 4.21 (condensation temperature of 61°C and evaporation temperature of 21°C). is achieved in heat pump mode and a global ORC efficiency of 5.7% is obtained in ORC mode (condenser exhaust temperature of 25°C and evaporator supply temperature of 88°C). [less ▲]

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See detailDIMENSIONNEMENT ET EXPÉRIMENTATION D’UNE UNITÉ POMPE À CHALEUR / ORC RÉVERSIBLE
Dumont, Olivier ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

Conference (2014)

L’union européenne doit réduire les émissions de gaz à effet de serre de 80% par rapport au niveau des années 90 d’ici 2020. Les ménages représentent 27% de la consommation finale. Dans ce cadre, les ... [more ▼]

L’union européenne doit réduire les émissions de gaz à effet de serre de 80% par rapport au niveau des années 90 d’ici 2020. Les ménages représentent 27% de la consommation finale. Dans ce cadre, les bâtiments dont la consommation d’énergie est quasi nulle (NZEB – Nearly Zero Energy Building) sont d’une importance considérable. A partir de 2019, tous les nouveaux bâtiments devront présenter une production d’énergie renouvelable supérieure à la consommation d’énergie primaire. C’est dans ce cadre que le concept de PAC/ORC prend tout son sens. Ce système innovant comprend une pompe à chaleur eau/eau (PAC) reliée à un toit solaire et à un échangeur de chaleur géothermique. Cette pompe à chaleur est également capable d'inverser son cycle et de fonctionner comme un Cycle Organique de Rankine (ORC). En utilisant le toit solaire comme source de chaleur, une grande quantité de chaleur est générée tout au long de l'année. Cette chaleur est utilisée en priorité pour couvrir les besoins de chauffage annuels et le surplus de chaleur généré au cours de l'été est utilisée pour produire de l'électricité dans l’unité PAC / ORC. L’article s’articule en 4 parties. Tout d’abord, l’introduction présente les trois modes de fonctionnement. Ensuite, les modèles des composants et l’évaluation des performances au point nominal de conception sont décrits. Par après, le dimensionnement et le choix des composants sont réalisés sur bases de simulations annuelles avec un pas de temps d’une heure. Enfin, les premiers résultats expérimentaux sont présentés. Un rendement de 5,7% est atteint en mode ORC (avec une température de condensation de 25°C et une température d’évaporation de 88°C) alors qu’un COP de 4,2 est obtenu en mode pompe à chaleur (avec une température de condensation de 61°C et une température d’évaporation de 21°C). [less ▲]

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See detailDESIGN, MODELING AND EXPERIMANTATION OF A REVERSIBLE HP-ORC PROTOTYPE
Dumont, Olivier ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

Conference (2014)

This paper presents an innovative system comprising a heat pump connected to a solar roof and a geothermal heat exchanger. This heat pump is also able to invert its cycle and operate as an ORC. By using ... [more ▼]

This paper presents an innovative system comprising a heat pump connected to a solar roof and a geothermal heat exchanger. This heat pump is also able to invert its cycle and operate as an ORC. By using the whole rooftop (hereunder called “absorber”) as a heat source, a large amount of heat is generated throughout the year. This heat is used in priority to cover the building annual heating needs and the surplus heat generated during the summer is utilized to generate electricity in a so-called HP/ORC module. This paper will thus focus on these two main points: designing of the prototype and results from experimentation. This paper demonstrates the feasibility of such a prototype with encouraging performance in ORC and HP modes. Experimentally, a COP of 4.2 is reached in heat pump mode and a global efficiency of 5.6 is obtained in ORC mode. Possible means of improvement and perspectives are finally described. [less ▲]

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See detailMethods to Increase the Robustness of Finite-Volume Flow Models in Thermodynamic Systems
Quoilin, Sylvain ULg; Bell, Ian ULg; Desideri, Adriano ULg et al

in Energies (2014), 7(3), 1621-1640

This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when ... [more ▼]

This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when modeling 1D heat exchangers or piping, e.g., in thermodynamic cycles involving a phase change. Issues, such as chattering or stiff systems, can lead to low simulation speed, instabilities and simulation failures. In the particular case of two-phase flow models, they are usually linked to a discontinuity in the density derivative between the liquid and two-phase zones. In this work, several methods to tackle numerical problems are developed, described, implemented and compared. In addition, methods available in the literature are also implemented and compared to the proposed approaches. Results suggest that the robustness of the models can be significantly increased with these different methods, at the price of a small increase of the error in the mass and energy balances. [less ▲]

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See detailPure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp
Bell, Ian ULg; Wronski, Jorrit; Quoilin, Sylvain ULg et al

in Industrial & Engineering Chemistry Research (2014), 53

Article Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp ACS ActiveView PDFHi-Res Print, Annotate, Reference QuickView PDF [2027 ... [more ▼]

Article Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp ACS ActiveView PDFHi-Res Print, Annotate, Reference QuickView PDF [2027 KB] PDF w/ Links[457 KB] Full Text HTML Abstract Supporting Info -> Figures Reference QuickView Add to ACS ChemWorx Ian H. Bell *†, Jorrit Wronski *‡, Sylvain Quoilin *†, and Vincent Lemort *† † Energy Systems Research Unit, University of Liège, Liège, Belgium ‡ Department of Mechanical Engineering, Technical University of Denmark, Kongens Lyngby, Denmark Ind. Eng. Chem. Res., 2014, 53 (6), pp 2498–2508 DOI: 10.1021/ie4033999 Publication Date (Web): January 13, 2014 Copyright © 2014 American Chemical Society OpenURL UNIV DE LIEGE *E-mail: ian.bell@ulg.ac.be., *E-mail: jowr@mek.dtu.dk., *E-mail: squoilin@ulg.ac.be., *E-mail: vincent.lemort@ulg.ac.be. ACS AuthorChoice Abstract Over the last few decades, researchers have developed a number of empirical and theoretical models for the correlation and prediction of the thermophysical properties of pure fluids and mixtures treated as pseudo-pure fluids. In this paper, a survey of all the state-of-the-art formulations of thermophysical properties is presented. The most-accurate thermodynamic properties are obtained from multiparameter Helmholtz-energy-explicit-type formulations. For the transport properties, a wider range of methods has been employed, including the extended corresponding states method. All of the thermophysical property correlations described here have been implemented into CoolProp, an open-source thermophysical property library. This library is written in C++, with wrappers available for the majority of programming languages and platforms of technical interest. As of publication, 110 pure and pseudo-pure fluids are included in the library, as well as properties of 40 incompressible fluids and humid air. The source code for the CoolProp library is included as an electronic annex. [less ▲]

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See detailThermoCycle: A Modelica library for the simulation of thermodynamic systems
Quoilin, Sylvain ULg; Desideri, Adriano ULg; Wronski, Jorrit et al

in Proceedings of the 10th International Modelica Conference 2014 (2014)

This paper presents the results of an on-going project to develop ThermoCycle, an open Modelica library for the simulation of low-capacity thermodynamic cycles and thermal systems. Special attention is ... [more ▼]

This paper presents the results of an on-going project to develop ThermoCycle, an open Modelica library for the simulation of low-capacity thermodynamic cycles and thermal systems. Special attention is paid to robustness and simulation speed since dynamic simulations are often limited by numerical constraints and failures, either during initialization or during integration. Furthermore, the use of complex equations of state (EOS) to compute thermodynamic properties significantly decreases the simulation speed. In this paper, the approach adopted in the library to overcome these challenges is presented and discussed. [less ▲]

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See detailDesign, Modeling and Performance Optimisation of a Reversible HP-ORC Prototype
Quoilin, Sylvain ULg; Dumont, Olivier ULg; Lemort, Vincent ULg

Conference (2013, October 08)

Building is one of the economical sectors where solutions are available to significantly reduce energy consumption and greenhouse gases emissions. Among other, heat pumps offer promising perspectives to ... [more ▼]

Building is one of the economical sectors where solutions are available to significantly reduce energy consumption and greenhouse gases emissions. Among other, heat pumps offer promising perspectives to provide energy-efficient space and sanitary hot water heating in many applications. This paper presents an innovative system comprising a heat pump connected to a solar roof and a geothermal heat exchanger. This heat pump is also able to invert its cycle and operate as an ORC. By using the whole rooftop (hereunder called “absorber”) as a heat source, a large amount of heat is generated throughout the year. This heat is used in priority to cover the building annual heating needs and the surplus heat generated during the summer is utilized to generate electricity in the so-called HP/ORC module. The same module can be used during winter as an efficient heat pump which radically reduces the complexity of the total system. The main advantage of the proposed technology is due to the reversibility of scroll machines, which have proven to operate efficiently both as compressor and as an expander in lab testing. [less ▲]

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See detailSizing models and performance analysis of waste heat recovery organic Rankine cycles for heavy duty trucks
Guillaume, Ludovic ULg; Legros, Arnaud ULg; Quoilin, Sylvain ULg et al

in Proceedings of the ASME ORC 2013 second international seminar on ORC power systems (2013, October 07)

This paper attempts to address this problematic of selecting the architecture, the expander and the working fluid for a waste heat recovery organic (or non-organic) Rankine cycle on a truck engine. It ... [more ▼]

This paper attempts to address this problematic of selecting the architecture, the expander and the working fluid for a waste heat recovery organic (or non-organic) Rankine cycle on a truck engine. It focuses especially on three expander technologies: the scroll, the piston and the screw expanders, and three working fluids: R245fa, ethanol and water. [less ▲]

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See detailImproved District Heating Network Operation by the Integration of High Temperature Heat Pumps
Sartor, Kevin ULg; Lemort, Vincent ULg; Dewallef, Pierre ULg

in Digital proceedings of the 8th Conference on Sustainable Development of Energy, Water and Environment Systems - SDEWES (2013, September 23)

Biomass Combined Heat and Power (CHP) plants connected to district heating networks are a very good opportunity to increase the share of renewable sources into energy systems. Frequently, important ... [more ▼]

Biomass Combined Heat and Power (CHP) plants connected to district heating networks are a very good opportunity to increase the share of renewable sources into energy systems. Frequently, important consumers are connected to ensure a stable base demand of heat throughout the year but they often have higher requirements in terms of temperature (i.e., steam) which involves high level of temperatures in the district heating network during the whole year and high levels of heat losses in the network. This contribution presents the possibility to decrease the level of temperature at which the district heating network operates and to use high temperature heat pumps connected locally at the consumption point to produce steam when needed. An investigation of the global design and integration through thermodynamic simulation models is realized for the University of Liège district heating network. This study is intended to determine the heat pump coefficient of performance and, therefore, to assess the balance between the savings in terms of heat losses and the additional heat pump electricity consumption. [less ▲]

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See detailSizing models and performance analysis of volumetric expansion machines for waste heat recovery through organic Rankine cycles on passenger cars
Guillaume, Ludovic ULg; Legros, Arnaud ULg; Quoilin, Sylvain ULg et al

Scientific conference (2013, September 09)

This paper aims at helping designers of waste heat recovery organic (or non-organic) Rankine cycles on internal combustion engines to best select the expander among the piston, scroll and screw machines ... [more ▼]

This paper aims at helping designers of waste heat recovery organic (or non-organic) Rankine cycles on internal combustion engines to best select the expander among the piston, scroll and screw machines, and the working fluids among R245fa, ethanol and water. The first part of the paper presents the technical constraints inherent to each machine through a state of the art of the three technologies. The second part of the paper deals with the modeling of such expanders. Finally, in the last part of the paper, performances of the various Rankine systems are compared and a decision array is built to select the most appropriate couple of fluid and expander. [less ▲]

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See detailInvestigation on a scroll expander for waste heat recovery on internal combustion engines
Legros, Arnaud ULg; Guillaume, Ludovic ULg; Lemort, Vincent ULg et al

Scientific conference (2013, September 09)

In the present article, a model of scroll expander will be introduced. This model is able to evaluate the performance of a given machine with influence of the geometry. Several losses are also included by ... [more ▼]

In the present article, a model of scroll expander will be introduced. This model is able to evaluate the performance of a given machine with influence of the geometry. Several losses are also included by the model such as internal leakages, heat transfers or mechanical losses. The forces generated by the gas pressure on the involutes can also be calculated. That expander model is used in order to demonstrate its potential and provide some guidelines to the design of a new expander suitable for the application. [less ▲]

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See detailExperimental performance characterization of a new single room ventilation device with heat recovery
Gendebien, Samuel ULg; Georges, Emeline ULg; Prieels, Luc et al

in Proceedings of the 34th AIVC conference (2013, September)

Nowadays, important efforts are made to reduce the residential building energy consumption. In this context, a growing interest for heat recovery ventilation has been observed during the last decades. The ... [more ▼]

Nowadays, important efforts are made to reduce the residential building energy consumption. In this context, a growing interest for heat recovery ventilation has been observed during the last decades. The present paper focuses on a new single room ventilation with heat recovery. Double flow ventilation is achieved through the integration of the unit into windows ledges. The developed device is particularly suitable compared to traditional centralized heat recovery ventilation units for retrofitted houses due to the absence of air extracting and air pulsing ducts through the house. The first part of the paper consists in describing the characteristics and properties of the developed device (volume, components, flow configuration, advantages and drawbacks). In the second part of the paper, an experimental approach is presented to characterize the unit. The criteria of performance are based on: - Thermal effectiveness of the unit (testing of a recovery heat exchanger), - Hydraulic aspects (flows delivered by the unit vs energy supplied to the unit), - Acoustic aspects. The overall performance of the unit can be established based on the experimental results described here above. Cartography of performance (ratio between the recovered heat and the supply electrical power) can be drawn, depending on the flow rates delivered by the unit and the indoor/outdoor temperature difference. The last part of the paper compares the new system with natural, simple exhaust ventilation and traditional centralized systems in terms of primary energy, consumer price and carbon dioxide emissions. Results show that the presented device seems more competitive than natural and simple exhaust ventilation for the Belgian climate. The single room ventilation investigated in this paper also shows better performance than most of the centralized ventilation systems tested on site. [less ▲]

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See detailInvestigation on a ventilation heat recovery exchanger: Modeling and experimental validation in dry and partially wet conditions
Gendebien, Samuel ULg; Bertagnolio, Stéphane ULg; Lemort, Vincent ULg

in Energy & Buildings (2013), 62

The present paper focuses on the development and experimental validation of a model of air-to-air heat exchanger dedicated to domestic mechanical heat recovery ventilation. The proposed model describes ... [more ▼]

The present paper focuses on the development and experimental validation of a model of air-to-air heat exchanger dedicated to domestic mechanical heat recovery ventilation. The proposed model describes dry and partially wet regimes. The first part of the paper presents a semi-empirical model based on the physical characteristics of the heat recovery device and relying on empirical correlations available in the literature for the convective heat transfer coefficients. In the case of partially wet regime, a moving boundary model is applied in order to predict sensible and latent heat transfer rates. A model developed with friction factor coefficients estimated by correlations from the literature is also presented in order to predict the hydraulic performance in dry conditions. The second part of the paper describes the experimental investigation conducted on an off-the-shelf heat exchanger. Experimental data are used to tune correlations for the determination of the convective heat transfer coefficient and validate the proposed simulation model of the ventilation heat recovery exchanger in partially wet conditions. The model developed to determine the hydraulic performance with existing correlations for the friction factor coefficient does not require a calibration. Finally, examples of use of the developed model are presented, which includes coupling the model with a building simulation model, a study of the influence of the humidity on the evolution of the latent and sensible heat transfer rates and strategies to avoid freezing in the heat exchanger. [less ▲]

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See detailExperimental study on an open-drive scroll expander integrated into an ORC (Organic Rankine Cycle) system with R245fa as working fluid
Declaye, Sébastien ULg; Quoilin, Sylvain ULg; Guillaume, Ludovic ULg et al

in Energy (2013), 15

The present paper focuses on the experimental characterization of an open-drive scroll expander integrated into an Organic Rankine cycle using R245fa as working fluid. The expander is a commercially ... [more ▼]

The present paper focuses on the experimental characterization of an open-drive scroll expander integrated into an Organic Rankine cycle using R245fa as working fluid. The expander is a commercially available air compressor that was modified to operate in expander mode. The ORC (Organic Rankine Cycle) system is designed for a nominal heat input of 20 kW and a nominal net power output of 1.8 kW. A total of 74 steady-state operating points are measured to evaluate the expander performance over a wide range of conditions. The operating parameters that are varied include the inlet pressure (from 9 to 12 bar), outlet pressure (from 1.5 to 4 bar) and rotational speed (from 2000 to 3500 rpm). The maximum isentropic efficiency and shaft power are, respectively, 75.7% and 2.1 kW. A maximum cycle efficiency of 8.5% is reached for evaporating and condensing temperatures of 97.5 °C and 26.6 °C respectively. For most of the tests, hot water is produced in the condenser and the system therefore behaves as a CHP (combined heat and power). Depending on the water temperature requirement, a power to heat ratio varying between 1.9% and 11.8% is obtained. Water over 50 °C can be produced with a power to heat ratio higher than 8%. The experimental data points are then used to generate a performance map of the expander. This performance map allows for simulation of the use of such an expander in other ORC system [less ▲]

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See detailModeling and simulation of the domestic energy use in Belgium following a bottom-up approach
Georges, Emeline ULg; Gendebien, Samuel ULg; Bertagnolio, Stéphane ULg et al

in Proceedings of the CLIMA 2013 11th REHVA World Congress & 8th International Conference on IAQVEC (2013, June)

The present paper presents a “bottom-up” approach dedicated to the modeling and simulation of the domestic energy use. This methodology focuses first on a microanalysis (i.e. modeling and simulation of a ... [more ▼]

The present paper presents a “bottom-up” approach dedicated to the modeling and simulation of the domestic energy use. This methodology focuses first on a microanalysis (i.e. modeling and simulation of a set of representative households). Results from this micro-analysis are then used and extended to allow drawing conclusions at a macro-scale. The methodology can be validated by comparing simulation results to annual national energy consumption indexes or synthetic load profiles (energy consumption profiles generated from values of predefined past periods). Once the method is validated, it can be used to study the impact of different retrofit scenarios on the annual energy use and on the energy demand profiles. This paper describes the methodology developed for Belgium. [less ▲]

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See detailTechno-economic survey of Organic Rankine Cycle (ORC) systems
Quoilin, Sylvain ULg; van den Broeck, Martijn; Declaye, Sébastien ULg et al

in Renewable & Sustainable Energy Reviews (2013), 22

New heat conversion technologies need to be developed and improved to take advantage of the necessary increase in the supply of renewable energy. The Organic Rankine Cycle is well suited for these ... [more ▼]

New heat conversion technologies need to be developed and improved to take advantage of the necessary increase in the supply of renewable energy. The Organic Rankine Cycle is well suited for these applications, mainly because of its ability to recover low-grade heat and the possibility to be implemented in decentralized lower-capacity power plants. In This paper, an overview of the different ORC applications is presented. A market review is proposed including cost figures for several commercial ORC modules and manufacturers. An in-depth analysis of the technical challenges related to the technology, such as working fluid selection and expansion machine issues is then reported. Technological constraints and optimization methods are extensively described and discussed. Finally, the current trends in research and development for the next generation of Organic Rankine Cycles are presented. [less ▲]

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See detailDesign of a small-scale organic Rankine cycle engine used in a solar power plant
Georges, Emeline ULg; Declaye, Sébastien ULg; Dumont, Olivier ULg et al

in International Journal of Low Carbon Technologies (2013)

Under the economic and political pressure due to the depletion of fossil fuels and global warming concerns, it is necessary to develop more sustainable techniques to provide electrical power. In this ... [more ▼]

Under the economic and political pressure due to the depletion of fossil fuels and global warming concerns, it is necessary to develop more sustainable techniques to provide electrical power. In this context, the present study aims at designing, building and testing a small-scale organic Rankine cycle (ORC) solar power plant ( 3 kWe) in order to define and optimize control strategies that could be applied to larger systems. This paper presents a first step of the design of the solar power plant and focuses more specifically on the ORC engine. This design is defined on the basis of simulation models of the ORC engine and takes into account some technical limitations such as the allowed operating ranges and the technical maturity of the components. The final configuration includes a diaphragm pump, two plate heat exchangers for the regenerator and the evaporator, an air-cooled condenser, two hermetic scroll expanders in series and R245fa as the working fluid. Simulations indicate that an efficiency close to 12% for the ORC engine can be reached for evaporating and condensing temperatures of 140 and 358C, respectively. [less ▲]

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See detailEtude tribologique sur des lubrifants solides à haute température
Legros, Arnaud ULg; Zaïdi, Hamid; Diny, Mouad et al

Poster (2013, May)

Actuellement, environ 2/3 de l’énergie libérée par la combustion de l’essence est rejetée sous forme de chaleur, soit dans les gaz d’échappement, soit dans le liquide de refroidissement. Un cycle de ... [more ▼]

Actuellement, environ 2/3 de l’énergie libérée par la combustion de l’essence est rejetée sous forme de chaleur, soit dans les gaz d’échappement, soit dans le liquide de refroidissement. Un cycle de Rankine peut être utilisé afin de valoriser la chaleur des gaz d’échappement. Cependant, aucune machine de détente commerciale n’est adaptée aux conditions de récupération d’énergie sur gaz d’échappement. La tribologie, plus particulièrement celle des lubrifiants solides à haute température, peut intervenir afin d’étudier les couples de matériaux adéquats pour réaliser les joints de la machine de détente du cycle. Cela permet de réduire les pertes globales de la machine et d’en améliorer le rendement. [less ▲]

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