References of "Quoilin, Sylvain"
     in
Bookmark and Share    
Peer Reviewed
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 ▲]

Detailed reference viewed: 339 (39 ULg)
Peer Reviewed
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)

Detailed reference viewed: 15 (2 ULg)
Full Text
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

Scientific conference (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 ▲]

Detailed reference viewed: 53 (7 ULg)
Full Text
Peer Reviewed
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

Conference (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 ▲]

Detailed reference viewed: 106 (21 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 41 (1 ULg)
Full Text
Peer Reviewed
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

Conference (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 ▲]

Detailed reference viewed: 83 (15 ULg)
Full Text
Peer Reviewed
See detailSemi-empirical correlation to model heat losses along solar parabolic trough collectors
Dickes, Rémi ULg; Lemort, Vincent ULg; Quoilin, Sylvain ULg

Conference (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 ▲]

Detailed reference viewed: 80 (13 ULg)
Full Text
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: 91 (8 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 46 (1 ULg)
Full Text
Peer Reviewed
See detailExperimental investigation of a reversible heat pump / organic Rankine cycle unit designed to be coupled with a passive house (Net Zero Energy Building)
Dumont, Olivier ULg; Quoilin, Sylvain ULg; Lemort, Vincent ULg

in International Journal of Refrigeration (2015), 54

This paper presents an innovative reversible Heat Pump/Organic Rankine Cycle (HP/ORC) experimental unit designed to be coupled to a Net Zero Energy Building (connected to a 120 m2 thermal solar roof and a ... [more ▼]

This paper presents an innovative reversible Heat Pump/Organic Rankine Cycle (HP/ORC) experimental unit designed to be coupled to a Net Zero Energy Building (connected to a 120 m2 thermal solar roof and a ground heat exchanger). The system can operate in three different modes: an ORC mode to produce electricity when a large amount of heat is collected by the solar roof, a direct heating mode using exclusively the solar roof, and a HP mode for space heating during cold weather conditions. This paper describes a comprehensive experimental campaign carried out on a prototype unit using a modified HVAC scroll compressor (4 kWe). From the results, the technical feasibility of the system is demonstrated. A cycle efficiency of 4.2% is achieved in ORC mode (with condensation and evaporation temperature respectively of 25 C and 88 C) and a COP of 3.1 is obtained in HP mode (with condensation and evaporation temperature respectively of 61 C and 21 C). [less ▲]

Detailed reference viewed: 47 (1 ULg)
Full Text
Peer Reviewed
See detailA generalized moving-boundary algorithm to predict the heat transfer rate of counterflow heat exchangers for any phase configuration
Bell, Ian; Quoilin, Sylvain ULg; Georges, Emeline ULg et al

in Applied Thermal Engineering (2015), 79

In this work, a novel and robust solution approach is presented that can be used to predict the steady-state thermal heat transfer rate for counterflow heat exchangers with any combination of single-phase ... [more ▼]

In this work, a novel and robust solution approach is presented that can be used to predict the steady-state thermal heat transfer rate for counterflow heat exchangers with any combination of single-phase and two-phase conditions within the heat exchanger. This methodology allows for multiple internal pinching points, as well as all permutations of subcooled liquid, two-phase and superheated vapor sections for the hot and cold fluids. A residual function based on the matching of the required and available thermal conductances in each section is derived, and Brent's method is then used to drive the residual to zero. Examples are presented for the application of this methodology to a water-heated n-Propane evaporator. The computational time required to execute the model for a simple case is on the order of one millisecond when the tabular interpolation methods of CoolProp are applied. Source code for the algorithm is provided in the Python programming language as an appendix. [less ▲]

Detailed reference viewed: 61 (6 ULg)
Full Text
Peer Reviewed
See detailEvaluation of simplified flexibility evaluation tools using a unit commitment model
Quoilin, Sylvain ULg; Nijs, Wouter; Hidalgo, Ignacio et al

in IEEE Digital Library (2015)

Different tools and methods have been proposed in the literature to assess the required flexibility resources and needs in a particular grid or geographical area. However, few of them are readily usable ... [more ▼]

Different tools and methods have been proposed in the literature to assess the required flexibility resources and needs in a particular grid or geographical area. However, few of them are readily usable in long term energy planning models because they require small time steps and detailed data. In this paper, two candidate methods to address the flexibility issues in such models are evaluated. A unit commitment model developed at the JRC, DispaSET 2.0, is used as a test case for the different simplified flexibility assessment tools. The modelled geographical area is Belgium, using historical data for the demand and VRE curves and their day-ahead forecast. Different VRE penetration scenarios are simulated to evaluate the flexibility of the power system. The simplified assessment tools are then run with the same inputs. Results indicate significant discrepancies between the detailed Unit Commitment model and the simplified tools. The underlying reasons are described and suggestions are formulated to improve their accuracy. [less ▲]

Detailed reference viewed: 10 (0 ULg)
Full Text
See detailKeynote Lecture: Past and current research trends in ORC power systems
Quoilin, Sylvain ULg

Speech/Talk (2015)

The past years have seen an almost-exponentially increasing number of published papers in the ORC research field. This profusion of publications sometimes makes it difficult to get a global picture of the ... [more ▼]

The past years have seen an almost-exponentially increasing number of published papers in the ORC research field. This profusion of publications sometimes makes it difficult to get a global picture of the main challenges and ongoing research. Recent literature has also been characterized by a certain lack of originality, the same methods and approaches being repeated multiple times with few new relevant insights. It is therefore of primary importance to highlight the state-of-the-art and foster new and original research, potentially resulting in new technological improvements. This keynote provides an overview of the state of the art and of the main research trends in ORC power systems. It does not aim at covering all research fields, but highlights and describes a few relevant topics originating from the previous ORC conferences and from the scientific literature. The main methods, mathematical tools and results are described in such a way to provide useful information for the replication of such studies. Recommendations are finally formulated, together with an open discussion regarding possible relevant future contributions in ORC research. [less ▲]

Detailed reference viewed: 71 (1 ULg)
See detailAddressing flexibility in energy system models
HIDALGO GONZALEZ, Ignacio; RUIZ CASTELLO, PABLO; SGOBBI, ALESSANDRA et al

Report (2015)

The present report summarises the discussions and conclusions of the international workshop on "Addressing flexibility in energy system models" held on December 4 and 5 2014 at the premises of the JRC ... [more ▼]

The present report summarises the discussions and conclusions of the international workshop on "Addressing flexibility in energy system models" held on December 4 and 5 2014 at the premises of the JRC Institute for Energy and Transport in Petten. Around 40 energy modelling experts and researchers from universities, research centres, the power industry, international organisations, and the European Commission (DGs ENER and JRC) met to present and discuss their views on the modelling of flexibility issues, the linkage of energy system models and sector-detailed energy models, the integration of high shares of variable renewable energy sources, and the representation of flexibility needs in power system models. The discussions took into account modelling and data-related methodological aspects, with their limitations and uncertainties, as well as possible alternatives to be implemented within energy system models. [less ▲]

Detailed reference viewed: 23 (1 ULg)
Full Text
Peer Reviewed
See detailSimulation of a passive house coupled with a reversible heat pump/organic Rankine cycle unit
Dumont, Olivier ULg; Carmo, Carolina; Randaxhe, François ULg et al

Conference (2014, December)

This paper presents a dynamic model of a passive house located in Denmark with a large solar absorber, a horizontal ground heat exchanger coupled with a HP/ORC unit. The HP/ORC reversible unit is a module ... [more ▼]

This paper presents a dynamic model of a passive house located in Denmark with a large solar absorber, a horizontal ground heat exchanger coupled with a HP/ORC unit. The HP/ORC reversible unit is a module able to work as an Organic Rankine Cycle (ORC) or as a heat pump (HP). There are 3 possible modes that need to be chosen optimally depending on the weather conditions, the heat demand and the temperature level of the storage. The ORC mode is activated, as long as the heat demand of the house is covered by the storage to produce electricity based upon the heat generated by the solar roof. The direct (free) heating is used when the storage cannot cover the heat demand of the house. Finally, when direct heating is not sufficient to cover the heat demand because of poor weather conditions, the HP mode is activated. Dynamic simulations of the whole system are presented for different typical days of the year in the Modelica language. A peak of 3.28 kW of power is reached in ORC mode with a heat input of 59.5 kW from the solar roof (23.9 kWh are produced during a typical summer day). In a representative winter day, 17.28 kWh are consumed by the heat pump with a daily average COP of 4.1. Conclusions regarding control strategies and enhancement of the global system are drawn. A control strategy with a low storage temperature set-point (50˚C) allows reducing electrical consumption from 11% up to 24% when compared to higher set-point (60˚C). The system performance to produce power could also be optimized if an extra tank is included to store heat uniquely to produce electricity with the ORC during the peak electricity consumption. Finally, this technology is a promising way to achieve Net Zero Energy Building at low price compared to competitive products (heat pump combined with PV for example). The system presents a higher global COP because the heat produced on the roof can heat the storage directly. [less ▲]

Detailed reference viewed: 70 (3 ULg)
Full Text
Peer Reviewed
See detailSimulation and optimization of a CHP biomass plant and district heating network
Sartor, Kevin ULg; Quoilin, Sylvain ULg; Dewallef, Pierre ULg

in Applied Energy (2014), 130

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

Biomass Combined Heat and Power (CHP) plants connected to district heating (DH) networks are recognized nowadays as a very good opportunity to increase the share of renewable sources into energy systems. However, as CHP plants are not optimized for electricity production, their operation is profitable only if a sufficient heat demand is available throughout the year. Most of the time, pre-feasibility studies are based on peak power demand and business plans only assume monthly or yearly consumption data. This approach usually turns out to overestimate the number of operating hours or oversize the plant capacity. This contribution presents a methodology intended to be simple and effective that provides accurate estimations of economical, environmental and energetic performances of CHP plants connected to district heating networks. A quasi-steady state simulation model of a CHP plant combined with a simulation model of the district heating network installed on the Campus of the University in Liège (Belgium) is used as an application framework to demonstrate the effectiveness of the selected approach. Based on the developed model and actual consumption data, several scenarios for energy savings are considered and ranked. The potential energy savings and resulting energy costs are estimated enabling more general conclusions to be drawn on the opportunity of using district heating networks in urban districts for Western Europe countries. [less ▲]

Detailed reference viewed: 132 (32 ULg)
Full Text
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

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: 187 (40 ULg)
Full Text
See detailIncreasing the efficiency of Organic Rankine Cycle Technology by means of Multivariable Predictive Control
Hernandez Naranjo, Jairo Andrés ULg; Desideri, Adriano ULg; Ionescu, Clara et al

Conference (2014, August 25)

The Organic Rankine Cycle (ORC) technology has become very popular, as it is extremely suitable for waste heat recovery from low-grade heat sources. As the ORC system is a strongly coupled nonlinear ... [more ▼]

The Organic Rankine Cycle (ORC) technology has become very popular, as it is extremely suitable for waste heat recovery from low-grade heat sources. As the ORC system is a strongly coupled nonlinear multiple-input multiple-output (MIMO) process, conventional control strategies (e.g. PID) may not achieve satisfactory results. In this contribution our focus is on the accurate regulation of the superheating, in order to increase the e fficiency of the cycle and to avoid the formation of liquid droplets that could damage the expander. To this end, a multivariable Model Predictive Control (MPC) strategy is proposed, its performance is compared to the one of PI controllers for the case of variable waste-heat source profi les. [less ▲]

Detailed reference viewed: 317 (9 ULg)
Full Text
Peer Reviewed
See detailOptimization of Biomass-Fuelled Combined Cooling, Heating and Power (CCHP) Systems Integrated with Subcritical or Transcritical Organic Rankine Cycles (ORCs)
Maraver, Daniel; Quoilin, Sylvain ULg; Royo, Javier

in Entropy (2014), 16(5), 2433-2453

This work is focused on the thermodynamic optimization of Organic Rankine Cycles (ORCs), coupled with absorption or adsorption cooling units, for combined cooling heating and power (CCHP) generation from ... [more ▼]

This work is focused on the thermodynamic optimization of Organic Rankine Cycles (ORCs), coupled with absorption or adsorption cooling units, for combined cooling heating and power (CCHP) generation from biomass combustion. Results were obtained by modelling with the main aim of providing optimization guidelines for the operating conditions of these types of systems, specifically the subcritical or transcritical ORC, when integrated in a CCHP system to supply typical heating and cooling demands in the tertiary sector. The thermodynamic approach was complemented, to avoid its possible limitations, by the technological constraints of the expander, the heat exchangers and the pump of the ORC. The working fluids considered are: n-pentane, n-heptane, octamethyltrisiloxane, toluene and dodecamethylcyclohexasiloxane. In addition, the energy and environmental performance of the different optimal CCHP plants was investigated. The optimal plant from the energy and environmental point of view is the one integrated by a toluene recuperative ORC, although it is limited to a development with a turbine type expander. Also, the trigeneration plant could be developed in an energy and environmental efficient way with an n-pentane recuperative ORC and a volumetric type expander. [less ▲]

Detailed reference viewed: 93 (3 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 173 (8 ULg)