Study of Organic Rankine Cycles for Waste Heat Recovery in Transportation Vehicles

Regulations for ICE-based transportation in the EU seek carbon dioxide emissions lower than 95 g CO2/km by 2020. In order to fulfill these limits, improvements in vehicle fuel consumption have to be achieved. One of the main losses of ICEs happens in the exhaust line. Internal combustion engines transform chemical energy into mechanical energy through combustion; however, only about 15-32% of this energy is effectively used to produce work, while most of the fuel energy is wasted through exhaust gases and coolant. Therefore, these sources can be exploited to improve the overall efficiency of the engine. Between these sources, exhaust gases show the largest potential of Waste Heat Recovery (WHR) due to its high level of exergy. Regarding WHR technologies, Rankine cycles are considered as the most promising candidates for improving Internal Combustion Engines. However, the implementation of this technology in modern passenger cars requires additional features to achieve a compact integration and controllability in the engine. While industrial applications typically operates in steady state operating points, there is a huge challenge taking into account its impact in the engine during typical daily driving profiles. This thesis contributes to the knowledge and characterization of an Organic Rankine Cycle coupled with an Internal Combustion Engine using ethanol as working fluid and a swash-plate expander as expansion machine. The main objective of this research work is to obtain and quantify the potential of Organic Rankine Cycles for the use of residual energy in automotive engines. To do this, an experimental ORC test bench was designed and built at CMT (Polytechnic University of Valencia), which can be coupled to different types of automotive combustion engines. Using these results, an estimation of the main variables of the cycle was obtained both in stationary and transient operating points. A potential of increasing ICE mechanical efficiency up to 3.7% could be reached at points of high load installing an ORC in a conventional turbocharged gasoline engine. Regarding transient conditions, a slightly simple and robust control based on adaptive PIDs, allows the control of the ORC in realistic driving profiles. High loads and hot conditions should be the starting ideal conditions to test and validate the control of the ORC in order to achieve high exhaust temperatures that justify the feasibility of the system. In order to deepen in the viability and characteristics of this particular application, some theoretical studies were done. A 1D model was developed using LMS Imagine.Lab Amesim platform. A potential improvement of 2.5% in fuel conversion efficiency was obtained at the high operating points as a direct consequence of the 23.5 g/kWh reduction in bsfc. To conclude, a thermo-economic study was developed taking into account the main elements of the installation costs and a minimum Specific Investment Cost value of 2030 €/kW was obtained. Moreover, an exergetic study showed that a total amount of 3.75 kW, 36.5% of exergy destruction rate, could be lowered in the forthcoming years, taking account the maximum efficiencies considering technical restrictions of the cycle components.Las normativas anticontaminantes para el transporte propulsado por motores de combustión interna alternativos en la Unión Europea muestran límites de emisión menores a 95 g CO2/km para el año 2020. Con el fin de cumplir estos límites, deberán ser realizadas mejoras en el consumo de combustible en los vehículos. Una de las principales pérdidas en los Motores de Combustión Interna Alternativos (MCIA) ocurre en la línea de escape. Los MCIA transforman la energía química en energía mecánica a través de la combustión; sin embargo, únicamente el 15-32% de esta energía es eficazmente usada para producir trabajo, mientras que la mayor parte es desperdiciada a través de los gases de escape y el agua de refrigeración del motor. Por ello, estas fuentes de energía pueden ser utilizadas para mejorar la eficiencia global del vehículo. De estas fuentes, los gases de escape muestran un potencial mayor de recuperación de energía residual debido a su mayor contenido exergético. De todos los tipos de Sistemas de Recuperación de Energía Residual, los Ciclos Rankine son considerados como los candidatos más prometedores para mejorar la eficiencia de los MCIA. Sin embargo, la implementación de esta tecnología en los vehículos de pasajeros modernos requiere nuevas características para conseguir una integración compacta y una buena controlabilidad del motor. Mientras que las aplicaciones industriales normalmente operan en puntos de operación estacionarios, en el caso de los vehículos con MCIA existen importantes retos teniendo en cuenta su impacto en el modo de conducción cotidianos. Esta Tesis contribuye al conocimiento y caracterización de un Ciclo Rankine Orgánico acoplado con un Motor de Combustión Interna Alternativo utilizando etanol como fluido de trabajo y un expansor tipo Swash-plate como máquina expansora. El principal objetivo de este trabajo de investigación es obtener y cuantificar el potencial de los Ciclos Rankine Orgánicos (ORC) para la recuperación de la energía residual en motores de automoción. Para ello, una instalación experimental con un Ciclo Rankine Orgánico fue diseñada y construida en el Instituto Universitario "CMT - Motores Térmicos" (Universidad Politécnica de Valencia), que puede ser acoplada a diferentes tipos de motores de combustión interna alternativos. Usando esta instalación, una estimación de las principales variables del ciclo fue obtenida tanto en puntos estacionarios como en transitorios. Un potencial de mejora en torno a un 3.7 % puede ser alcanzada en puntos de alta carga instalando un ORC en un motor gasolina turboalimentado. Respecto a las condiciones transitorias, un control sencillo y robusto basado en PIDs adaptativos permite el control del ORC en perfiles de conducción reales. Las condiciones ideales para testear y validar el control del ORC son alta carga en el motor comenzando con el motor en caliente para conseguir altas temperaturas en el escape que justifiquen la viabilidad de estos ciclos. Para tratar de profundizar en la viabilidad y características de esta aplicación particular, diversos estudios teóricos fueron realizados. Un modelo 1D fue desarrollado usando el software LMS Imagine.Lab Amesim. Un potencial de mejora en torno a un 2.5% en el rendimiento efectivo del motor fue obtenido en condiciones transitorias en los puntos de alta carga como una consecuencia directa de la reducción de 23.5 g/kWh del consumo específico. Para concluir, un estudio termo-económico fue desarrollado teniendo en cuenta los costes de los principales elementos de la instalación y un valor mínimo de 2030 €/kW fue obtenido en el parámetro de Coste Específico de inversión. Además, el estudio exergético muestra que un total de 3.75 kW, 36.5 % de la tasa de destrucción total de exergía, podría ser reducida en los años futuros, teniendo en cuenta las máximas eficiencias considerando restricciones técnicas en los componentes del ciclo.Les normatives anticontaminants per al transport propulsat per motors de combustió interna alternatius a la Unió Europea mostren límits d'emissió menors a 95 g·CO2/km per a l'any 2020. Per tal d'acomplir aquests límits, s'hauran de realitzar millores al consum de combustible dels vehicles. Una de les principals pèrdues als Motors de combustió interna alternatius (MCIA) ocorre a la línia d'escapament. Els MCIA transformen l'energia química en energia mecànica a través de la combustió; però, únicament el 15-32% d'aquesta energia és usada per produir treball, mentre que la major part és desaprofitada a través dels gasos d'escapament i l'aigua de refrigeració del motor. Per això, aquestes fonts d'energia poden ser utilitzades per millorar l'eficiència global del vehicle. Considerant aquestes dues fonts d'energia, els gasos d'escapament mostren un potencial major de recuperació d'energia residual debut al seu major contingut exergètic. De tots els tipus de Sistemes de Recuperació d'Energia Residual, els Cicles Rankine són considerats com els candidats més prometedors per millorar l'eficiència dels MCIA. No obstant, la implementació d'aquesta tecnologia en els vehicles de passatgers moderns requereix un desenvolupament addicional per aconseguir una integració compacta i una bona controlabilitat del motor. Mentre que les aplicacions industrials normalment operen en punts d'operació estacionaris, en el cas dels vehicles amb MCIA hi han importants reptes a solucionar tenint en compte el funcionament en condicions variables del motor i el seu impacte en la manera de conducció quotidiana del usuari. Aquesta Tesi contribueix al coneixement i caracterització d'un Cicle Rankine Orgànic (ORC) acoblat amb un motor de combustió interna alternatiu (MCIA) utilitzant etanol com a fluid de treball i un expansor tipus Swash-plate com a màquina expansora. El principal objectiu d'aquest treball de recerca és obtenir i quantificar el potencial dels ORCs per a la recuperació de l'energia residual en motors d'automoció. Per aconseguir-ho, una instal·lació experimental amb un ORC va ser dissenyada i construïda a l'Institut "CMT- Motores Térmicos" (Universitat Politècnica de València). Esta installació pot ser acoblada a diferents tipus de MCIAs. Mitjançant assajos experimentals en aquesta installació, una estimació de les principals variables del cicle va ser obtinguda tant en punts estacionaris com en punts transitoris. Un potencial de millora al voltant d'un 3.7% pot ser aconseguida en punts d'alta càrrega instal·lant un ORC acoblat a un motor gasolina turboalimentat. Pel que fa a les condicions transitòries, un control senzill i robust basat en PIDs adaptatius permet el control del ORC en perfils de conducció reals. Les condicions ideals per a testejar i validar el control de l'ORC són alta càrrega al motor començant amb el motor en calent per aconseguir altes temperatures d'escapament que justifiquen la viabilitat d'aquests cicles. Per tractar d'aprofundir en la viabilitat i característiques d'aquesta aplicació particular, diversos estudis teòrics van ser realitzats. Un model 1D va ser desenvolupat usant el programari LMS Imagine.Lab Amesim. Un potencial de millora al voltant d'un 2.5% en el rendiment efectiu del motor va ser obtingut en condicions transitòries en els punts d'alta càrrega com una conseqüència directa de la reducció de 23.5 g/kWh al consum específic. Per concloure, un estudi termo-econòmic va ser desenvolupat tenint en compte els costos dels principals elements de la installació i un valor mínim de 2030 €/kW va ser obtingut en el paràmetre del Cost Específic d'Inversió. A més, l'estudi exergètic mostra que un total de 3.75 kW, 36.5% de la taxa de destrucció total d'exergia, podria ser recuperat en un pròxim, considerant restriccions tècniques en els components del cicle i tenint en compte les màximes eficiències que es poden aconseguir.Royo Pascual, L. (2017). Study of Organic Rankine Cycles for Waste Heat Recovery in Transportation Vehicles [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84013TESI

Multi-objective optimization of a bottoming Organic Rankine Cycle (ORC) of gasoline engine using swash-plate expander

This paper presents a mathematical model of a bottoming Organic Rankine Cycle coupled to a 2 l turbocharged gasoline engine to optimize the cycle from a thermo-economic and sizing point of view. These criteria were optimized with different cycle values. Therefore, a methodology to optimize the ORC coupled to Waste Heat Recovery systems in vehicle applications is presented using a multiobjective optimization algorithm. Multi-objective optimization results show that the optimum solution depend on the importance of each objective to the final solution. Considering thermo-economic criteria as the main objective, greater sizes will be required. Considering sizing criteria as the main objective, higher thermo-economic parameters will be obtained. Therefore, in order to select a single-solution from the Pareto frontier, a multiple attribute decision-making method (TOPSIS) was implemented in order to take into account the preferences of the Decision Maker. Considering the weight factors 0.5 for Specific Investment Cost (SIC), 0.3 for the area of the heat exchangers (Atot) and 0.2 for Volume Coefficient (VC) and the boundaries of this particular application, the result is optimized with values of 0.48 m2 (Atot), 2515 /kW (SIC) and 2.62 MJ/m3 (VC). Moreover, the profitability of the project by means of the Net Present Value and the Payback has been estimated.This work is part of a research project called "Evaluation of bottoming cycles in IC engines to recover waste heat energies" funded by a National Project of the Spanish Government with reference TRA2013-46408-R. Authors want to acknowledge the "Apoyo para la investigacion y Desarrollo (PAID)" grant for doctoral studies (FPI S2 2015 1067). Authors acknowledge to ModeFRONTIER (ESTECO) because its support.Galindo, J.; Climent, H.; Dolz Ruiz, V.; Royo-Pascual, L. (2016). Multi-objective optimization of a bottoming Organic Rankine Cycle (ORC) of gasoline engine using swash-plate expander. Energy Conversion and Management. 126:1054-1065. https://doi.org/10.1016/j.enconman.2016.08.053S1054106512

Advanced exergy analysis for a bottoming organic rankine cycle coupled to an internal combustion engine

This paper deals with the evaluation and analysis of a bottoming ORC cycle coupled to an IC engine by means of conventional and advanced exergy analysis. Using experimental data of an ORC coupled to a 2 l turbocharged engine, both conventional and advanced exergy analysis are carried out. Splitting the exergy in the advanced exergy analysis into unavoidable and avoidable provides a measure of the potential of improving the efficiency of this component. On the other hand, splitting the exergy into endogenous and exogenous provides information between interactions among system components. The result of this study shows that there is a high potential of improvement in this type of cycles. Although, from the conventional analysis, the exergy destruction rate of boiler is greater than the one of the expander, condenser and pump, the advanced exergy analysis suggests that the first priority of improvement should be given to the expander, followed by the pump, the condenser and the boiler. A total amount of 3.75 kW (36.5%) of exergy destruction rate could be lowered, taking account that only the avoidable part of the exergy destruction rate can be reduced.This work is part of a research project called "Evaluation of bottoming cycles in IC engines to recover waste heat energies" funded by a National Project of the Spanish Government with reference TRA2013-46408-R. Authors want to acknowledge the "Apoyo para la investigacion y Desarrollo (PAID)" grant for doctoral studies (FPI S2 2015 1067).Galindo, J.; Ruiz Rosales, S.; Dolz Ruiz, V.; Royo-Pascual, L. (2016). Advanced exergy analysis for a bottoming organic rankine cycle coupled to an internal combustion engine. Energy Conversion and Management. 126:217-227. https://doi.org/10.1016/j.enconman.2016.07.080S21722712

Dynamic tests and adaptive control of a bottoming organic Rankine cycle of IC engine using swash-plate expander

This paper deals with the experimental testing of a bottoming Organic Rankine Cycle (ORC) integrate in a 2 l turbocharged gasoline engine using ethanol as working fluid. The main components of the cycle are a boiler, a condenser, a pump and a swash-plate expander. Both steady and transient tests were performed in three engine operating points to understand the behavior and inertia of the system. Pressure-Volume diagram during these transients were presented and analyzed. Operating parameters of the expander, such as expander speed and boiler power, were shifted. The objective of these tests is to understand the inertia of the system and to have a robust control in all the possible transient tests. New European Driving Cycle was tested with and without the expander because it is supposed to represent the typical usage of a car in Europe. It was used to validate the control of the ORC in realistic dynamic conditions of the engine. The importance of each parameter was analyzed by fixing all the parameters, changing each time one specific value. The main result of this paper is that using a slightly simple and robust control based on adaptive PIDs, the two dynamic effects of an ORC could be taken into account, i.e. high inertia effects (boiler and condenser) and low inertia effects (pump and volumetric expander).This work is part of a research project called "Evaluation of bottoming cycles in IC engines to recover waste heat energies" funded by a National Project of the Spanish Government with reference TRA2013-46408-R. The authors thank also to Raul Lujan and Rafael Carrascosa for their contribution in the testing process. Authors want to acknowledge the "Apoyo para la investigacion y Desarrollo (PAID)" grant for doctoral studies (FPI S2 2015 1067).Torregrosa, AJ.; Galindo, J.; Dolz Ruiz, V.; Royo-Pascual, L.; Haller, R.; Melis, J. (2016). Dynamic tests and adaptive control of a bottoming organic Rankine cycle of IC engine using swash-plate expander. Energy Conversion and Management. 126:168-176. https://doi.org/10.1016/j.enconman.2016.07.078S16817612

Effect of Gamma Radiation on the Processability of New and Recycled PA-6 Polymers

The growing quantities of plastic waste have raised environmental concerns, with almost a quarter of disposed plastics being sent to landfill. This has motivated research efforts into various recycling technologies to ease dependence on fossil resources, increasing circularity. Irradiation of various kinds, such as electron beam, beta and gamma rays, has been studied in the past as a way of revamping end-of-life polymer properties. The present work focuses on the effects of gamma radiation on the processability of new and recycled polymers, which is intimately linked with their rheological properties. In this study, both virgin and recycled polymers were irradiated under different radiation doses and the effects of the radiation on their viscosity assessed and compared. Results were analyzed making use of different theoretical relationships, and the causes of the changes in rheology were investigated by means of various characterization techniques, such as GPC, FTIR, EPR and DSC. Finally, the rheological curves of all samples were fitted to the Ostwald–de Waele relationship and the dependence of its parameters on the absorbed dose fitted to a function

Modeling and Experimental Validation of a Volumetric Expander Suitable for Waste Heat Recovery from an Automotive Internal Combustion Engine Using an Organic Rankine Cycle with Ethanol

Waste heat recovery (WHR) in exhaust gas flow of automotive engines has proved to be a useful path to increase the overall efficiency of internal combustion engines (ICE). Recovery potentials of up to 7% are shown in several works in the literature. However, most of them are theoretical estimations. Some present results from prototypes fed by steady flows generated in an auxiliary gas tank and not with actual engine exhaust gases. This paper deals with the modeling and experimental validation of an organic Rankine cycle (ORC) with a swash-plate expander integrated in a 2 L turbocharged petrol engine using ethanol as working fluid. A global simulation model of the ORC was developed with a maximum difference of 5%, validated with experimental results. Considering the swash-plate as the main limiting factor, an additional specific submodel was implemented to model the physical phenomena in this element. This model allows simulating the fluid dynamic behavior of the swash-plate expander using a 0D model (Amesim). Differences up to 10.5% between tests and model results were found.This work is part of a research project called "Evaluation of bottoming cycles in ICEs to recover waste heat energies" funded by a National Project of the Spanish Government with reference TRA2013-46408-R. The authors thank also to Raul Lujan and Rafael Carrascosa for their contribution in the testing process. Authors want to acknowledge the "Apoyo para la investigacion y Desarrollo (PAID)" grant for doctoral studies (FPI S2 2015 1067).Galindo, J.; Dolz Ruiz, V.; Royo-Pascual, L.; Haller, R.; Melis, J. (2016). Modeling and Experimental Validation of a Volumetric Expander Suitable for Waste Heat Recovery from an Automotive Internal Combustion Engine Using an Organic Rankine Cycle with Ethanol. Energies. 9(279):1-18. https://doi.org/10.3390/en9040279S118927

Automotive engine exhaust gas energy recovery with an organic rankine cycle

[EN] Waste Heat Recovery (WHR) in exhaust gas flow of automotive engines has proved to be a path to increase the overall efficiency of automotive vehicles. Recovery potential of up to 7% are showed in several works in the literature, however most of them are theoretical estimations, and only in some of them there are results from prototypes fed not with actual engine exhaust gases but steady flow generated in an auxiliary gas tank. The main objective of this project is the theoretical-experimental evaluation of a waste heat recovery system based on an Organic Rankine Cycle (ORC), applied to automotive reciprocating internal combustion engines in actual driving conditions. The purpose of this system is to achieve an improvement in the overall efficiency of the automotive engine and a subsequent reduction in fuel consumption and pollutant emissions. In order to perform an experimental evaluation of this system, an experimental ORC test bench is designed and built at CMT, which can be coupled to different types of automotive combustion engines (an automotive diesel engine, a Heavy Duty diesel engine and an automotive petrol engine). The specific objective of this research work is to obtain and quantify the potential of this technology for the use of residual energy in automotive engines. The ORC cycle experimental facility, which aims to design and build in this project, will be used as a demonstrator of this technology applied to automotive engines. If satisfactory results are obtained in this project, in a second phase, the experimental setup will be redesigned to compact it and integrate it into a vehicle with which to study the feasibility for the economic exploitation of this system.[ES] La recuperación del calor residual en los gases de escape de los motores de automoción se muestra como un camino para mejorar la eficiencia en los vehículos. Potenciales de recuperación de hasta el 7% se muestran en diferentes estudios en la literatura, sin embargo, en la mayor parte de los casos estos estudios son teóricos, y solo en algunos de ellos los resultados no provienen de prototipos alimentados con generadores de gases que simulan los gases de escape de un motor en condiciones estacionarias. El objetivo principal de este proyecto es la evaluación teórico-experimental del potencial de recuperación de un sistema de aprovechamiento energía térmica residual, mediante un Ciclo Rankine Organico (ORC), aplicado a motores de combustión interna alternativos en condiciones reales de funcionamiento. La finalidad de este sistema será conseguir una mejora en la eficiencia de los motores de automoción y la consiguiente reducción en consumo de combustible y en emisiones de contaminantes. Para realizar la evaluación experimental de este sistema, una instalación experimental ORC fue diseñada y construida en el CMT, la cual puede ser acoplada a diferentes tipos de motores de combustión de automoción (motor Diésel de automovil, motor Diésel de vehículo pesado y motor de automóvil de gasolina). El objetivo específico de este trabajo de investigación será obtener y cuantificar el verdadero potencial que ofrece esta tecnología de aprovechamiento de energía residual en motores de automoción. La instalación experimental del ciclo ORC que se pretende diseñar y construir en el presente proyecto se utilizará como un demostrador de este tipo de tecnología aplicada a motores de automoción. Si se obtuvieran resultados satisfactorios de este proyecto, en una segunda fase, la instalación sería rediseñada para compactarla e integrarla en un vehículo con el que estudiar la viabilidad en la explotación económica de este sistema.Royo Pascual, L. (2014). Automotive engine exhaust gas energy recovery with an organic rankine cycle. http://hdl.handle.net/10251/59802Archivo delegad

Bromodicyclopentadienylniobium complexes

The reaction of NbX5 (X=Cl, Br) with an excess of NaCp (Cp=C5H5) followed by the addition of HBr gives (η5-C5H5)2NbBr2 (I) in low yield. The reduction of I with Na/Hg or NaNaph in a molar ratio 1/1 gives (η5-C5H5)2NbBr (II), whereas the same reaction in the presence of π-acid ligands gives (η5-C5H5)2NbBrL (III, L=CO; IV, L=PMe2Ph; V, L=P(OMe)3; VI, L=PhC≡CPh; VIII, L=PhC≡CH). Finally, the reduction of I with Na/Hg in a molar ratio 2/1 gives the dimer (η5-C5H5)4Nb2Br3 (VIII), which contains both niobium(III) and niobium(IV). The chemical and structural characteristics of all these compounds are described.Comisión Asesora de Investigación Científica y Técnic