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See detailContribution to the Characterization of Piston Expanders for Their Use in Small-scale Power Production Systems
Oudkerk, Jean-François ULg

Doctoral thesis (2016)

Piston expanders are well suited for small scale power generation (<50kW) using heat engines such as Ericsson engine or Organic Rankine Cycle (ORC) system. Both systems offer the possibility to use ... [more ▼]

Piston expanders are well suited for small scale power generation (<50kW) using heat engines such as Ericsson engine or Organic Rankine Cycle (ORC) system. Both systems offer the possibility to use renewable energy sources and are increasingly considered in light of the economic and environmental context. This thesis aims at contributing to the knowledge and the development of piston expanders by presenting modeling, simulation and experimental investigations. Two types of piston engine models are proposed. The first type (denoted as “detailed”) describes the shaft angle (or time) evolution of the state of the fluid in the control volume limited by the cylinder wall and the piston. The second type of model (denoted as “semi-empirical”) is based on theoretical indicator diagram. A calibration process is proposed and applied with the measurement collected on two different expanders. The detailed model is first used to simulate an Ericsson engine. The simulations allow for the optimization of the pressure ratio, the determination of the ratio between the swept volumes of the expander and the compressor, the computation of the valve timing and the evaluation of the potential performances. The main modifications made to turn an available Internal Combustion Engine (ICE) into an Ericsson engine are described. This prototype is then tested but did not run as expected. The identified reasons are a too high leakage rate, a too large cut-off ratio and a too low expander supply temperature. These three features led to insufficient pressure. Nevertheless, a compressor is used to rise the pressure up to 7 bar in order to test the expander part. This expander shows a maximal isentropic efficiency of 59% at 600 RPM with a pressure ratio of 5. A swash-plate expander integrated into an ORC using R245fa is also investigated in a wide range of operating conditions. Performance maps in terms of pressure ratio and rotational speed are given. Maximal reached isentropic efficiency is 54% at 2500 RPM for a pressure ratio of 10.5. Experimental results obtained on both expanders are analyzed with the same methodology to assess the importance of each source of losses. This methodology is based on the disaggregation of the isentropic efficiency into different factors. Each of these factors represents one source of losses. In-cylinder pressure measurements are performed in order to measure mechanical losses. Leakage effects are simulated with the detailed model. Finally, an Ericsson engine-based m-CHP unit and an ORC-based m-CHP unit using the swash-plate expander are simulated with the validated semi-empirical model. Ericsson engine system shows a 6.5% electrical efficiency while the ORC system shows en efficiency of 8.2%. For both systems, possible improvements are simulated. It is shown, among other things, that the benefit of an increase of the built-in volume is limited by the decrease of the mechanical efficiency. [less ▲]

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See detailDevelopment of a semi-analytical model of volumetric expander for system-level simulation.
Oudkerk, Jean-François ULg

in Proceedings of ECOS 2016 (2016, June)

Organic Rankine cycles are particularly well suited for recovering energy from low-grade heat sources, such as industrial waste, engine exhaust gas or solar concentrated power. In ow-capacity systems ... [more ▼]

Organic Rankine cycles are particularly well suited for recovering energy from low-grade heat sources, such as industrial waste, engine exhaust gas or solar concentrated power. In ow-capacity systems, volumetric expanders are often preferred to turbomachines because of their reliability, robustness, low rotational speed and their ability to handle high pressure ratios… Different types of machines have been investigated and successfully tested by the uthors and tools have been developed in order to analyse experimental data. Semi-empirical odel was built to analyse losses, detect potential improvement and simulate performances. This paper present a simple and fastcomputing semi-analytical model useful for simulate dynamic system integrating volumetric expander. This model is validated on experimental data and compare to black-box model. [less ▲]

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See detailExperimental performance of a piston expander in a smallscale organic Rankine cycle
Oudkerk, Jean-François ULg; Dickes, Rémi ULg; Dumont, Olivier ULg et al

in IOP Conf. Series: Materials Science and Engineering 90 (2015) (2015)

Volumetric expanders are suitable for more and more applications in the field of micro- and small-scale power system as waster heat recovery or solar energy. This paper present an experimental study ... [more ▼]

Volumetric expanders are suitable for more and more applications in the field of micro- and small-scale power system as waster heat recovery or solar energy. This paper present an experimental study carried out on a swatch-plate piston expander. The expander was integrated into an ORC test-bench using R245fa. The performances are evaluated in term of isentropic efficiency and filling factor. The maximum efficiency and power reached are respectively 53% and 2 kW. Inside cylinder pressure measurements allow to compute mechanical efficiency and drown P-V diagram. A semi-empirical simulation model is then proposed, calibrated and used to analyse the different sources of losses. [less ▲]

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See detailTheorical study of a volumetric hot air Joule cycle engine
Oudkerk, Jean-François ULg; Lemort, Vincent ULg

in Proceedings of the 3rd International Conference on Microgeneration and Related Technologies (2013, April)

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See detailLancement d’une unité de cogénération biomasse de 30 kWel sur le marché
Oudkerk, Jean-François ULg

Master's dissertation (2012)

La cogénération est une technique de production rationnelle et efficace de l’énergie. Le principe est simple : produire de l’électricité et de la chaleur simultanément. Le but étant d’éviter les pertes ... [more ▼]

La cogénération est une technique de production rationnelle et efficace de l’énergie. Le principe est simple : produire de l’électricité et de la chaleur simultanément. Le but étant d’éviter les pertes d’énergie thermique inévitablement liées aux centrales électriques de grosse puissance. Cette technique permet d’économiser de l’énergie primaire, de réduire les émissions de CO2 et de générer un revenu pour l’exploitant. Pour ses divers avantages, elle est mise en avant par la Commission européenne comme technologie à développer pour atteindre les objectifs énergétiques de l’Union Européenne. Depuis quelques années, la micro cogénération arrive sur le marché. Malgré les estimations prometteuses, elle n’a pas encore réussi à atteindre le marché de masse comme l’ont fait certaines technologies relatives à la production d’énergie verte pour le particulier (on pense notamment au succès des panneaux photovoltaïques). Mais les experts s’accordent à dire que, désormais, tous les facteurs sont réunis pour que le marché de la cogénération se développe comme il le mérite. Ce travail commence par analyser les facteurs qui influencent le marché de la cogénération et tente d’expliquer pourquoi celui-ci n’en est qu’à sa phase de lancement. L’analyse de ces facteurs montre que le marché a connu un début difficile mais qu’aujourd’hui, tout est en place pour qu’il entre dans sa phase de croissance. Le but de cette démarche est d’évaluer le potentiel commercial d’un produit innovant proposé par CORETEC. Afin de déterminer ce potentiel, un modèle de la rentabilité économique d’une unité de cogénération est proposé. Ce modèle se base sur un profil de consommation de chaleur horaire pour déterminer la production d’énergie et la consommation en combustible, heure par heure, de la cogénération tout au long d’une année. Connaissant la production et la consommation, il est possible de déterminer la rentabilité du projet via trois critères : le temps de retour actualisé, la valeur actuelle nette et le taux de rentabilité interne. Ce modèle est utilisé pour déterminer le client cible en Région wallonne. Ce dernier est le client pour qui le produit offre une rentabilité économique. Après avoir détermine le profil du client cible, un nombre de clients potentiels est déterminé sur base de statistiques énergétiques. Pour terminer, une comparaison avec un produit standard du marché est effectuée et l’influence des mécanismes de soutien mis en place par la Région wallonne est étudiée. [less ▲]

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See detailModélisation, simulation et contrôle d’un cycle de Rankine organique en régime dynamique.
Oudkerk, Jean-François ULg

Master's dissertation (2010)

Organic Rankine cycles (ORC) are thermodynamic cycles that allow the production of mechanical energy form low temperature heat source. Additionally, they are particularly suitable to small scale units ... [more ▼]

Organic Rankine cycles (ORC) are thermodynamic cycles that allow the production of mechanical energy form low temperature heat source. Additionally, they are particularly suitable to small scale units. This work introduces the use of ORC to recover a variable flow rate and temperature heat source. As heat source’s characteristics are variables, it is judicious to be able to simulate the dynamic behavior of the system. The suggested model focuses mainly on dynamic behaviour of heat exchangers. A first model in steady state is primarily proposed and validated. The dynamic model is then described and also validated. Two controls strategies are suggested and compared. Dynamic simulation’s results show that control strategies proposed are well adapted to the system. An overall efficiency of 7.94 % is obtained for considered heat source. [less ▲]

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