Etude locale de la thermique dans les piles à combustibles pour application automobile. Corrélation à la durée de vie

One of the main challenges for Proton Exchange Membrane Fuel Cells development is the performance loss, which largely limits the durability. The study of the degradation phenomena of the different MEA components is a challenge addressed by many researchers, but a study at a stack scale is needed in order to better understand the ageing mechanisms. Indeed, in an industrial fuel cell the operating conditions are not homogeneous as for laboratory fuel cells, especially as regards thermal aspects. The heterogeneities are particularly emphasized for automotive fuel cells, because of the compactness constraint of the cooling circuit. Moreover, the requirements of cold start should be considered, as well as the inertial effects of the stacks and the increased heterogeneities during the driving cycles.In this work, the effects of the temperature heterogeneities and hot spots on the automotive fuel cell performances and degradations are investigated. The study is conducted in different conditions: nominal conditions, load/thermal cycling and New European Driving Cycles (NEDC).The work is composed of an experimental study, which consists of ageing tests on fuel cells and on-line diagnosis at both global and local scales. At the end of the tests, post-mortem analyses of the aged components are conducted. In parallel, a physic-based model is developed in order to predict the local temperature and humidity in the different components of the cell. Then, the impact of the reactive gases and cooling flow fields design on the thermal and water management of the cell is investigated. Finally, the experimental and modeling results are coupled in order to investigate the correlation between heat management, water management and degradations.L'un des principaux freins au développement des piles à combustible de type PEMFC (Proton Exchange Membrane Fuel Cell) est lié aux phénomènes de dégradation des performances qui les pénalisent encore en termes de durée de vie. L'étude de ces phénomènes au niveau des composants de l’AME est un thème abordé aujourd'hui par de nombreuses équipes de recherche, mais une étude à une échelle d’un stack est nécessaire pour mieux comprendre les mécanismes en jeu. En effet, dans un stack les conditions de fonctionnement ne sont pas homogènes comme dans les cellules de laboratoire, notamment au niveau thermique. Ceci est particulièrement exacerbé dans les piles pour application automobile, dont la compacité contraint fortement la conception du circuit de refroidissement. De plus, les exigences en termes de démarrage à froid sont à prendre en compte, avec notamment la limitation de l'inertie thermique de l'empilement ou l'apparition d'hétérogénéités plus fortes pendant les phases transitoires.Ce travail de thèse se propose d'étudier l'effet d'hétérogénéités de température sur la performance d'une pile en application automobile et sa dégradation. L'étude est menée dans différentes conditions de fonctionnement: fonctionnement nominal, cyclage thermique et cyclage NEDC (New European Driving Cycles).Cette étude comporte une partie expérimentale, centrée sur des essais de vieillissement en pile et un travail sur le diagnostic électrochimique global et local. Elle est complétée par des expertises post-mortem des assemblages membrane-électrodes et des plaques testées. En parallèle, un travail de modélisation est mené pour relier les constatations expérimentales à une description des phénomènes en présence. L'influence du design des canaux de réactifs et de caloporteur sur le fonctionnement des piles est étudiée. Enfin, l’effet de la gestion thermique sur la dégradation des performances et sur la détérioration des composants de la pile est étudié

Registro de información en motores de automóviles y desarrollo de un ciclo de conducción piloto para la ciudad de Pereira usando herramientas de diagnóstico de bajo costo

(Eng) The objective of this paper is to present a methodology designed to develop a driving cycle to model traffic in the Pereira city in Colombia. Under the scope of this pilot work, four different gasoline passenger cars furnished with real time datalogging equipment were used to collect speed-time data under actual traffic along Pereira urban area. The speed-acceleration characteristics were analyzed, and target driving parameters were defined and evaluated. The designed method for building the driving cycle was then applied. As a result, a simple driving schedule for analyzing propulsion, fuel consumption rate, and emission control strategies of automobiles under Pereira downtown conditions has been proposed. Under the scope of the same project, was also studied the utility of the engine specific data collected during the vehicle operation for the purposes of engine performance assessment.(Spa) El objetivo de este trabajo es presentar una metodología para la obtención de un ciclo de conducción representativo del tráfico en la ciudad de Pereira, Colombia, usando herramientas de bajo costo. Se escogieron cuatro vehículos equipados con sistemas de registro de velocidad y aceleración para circular en uno de los corredores viales más congestionados de la ciudad. Las características de velocidad y aceleración fueron analizadas y se evaluaron y definieron los parámetros de conducción. Se diseñó un método para construir el ciclo de conducción y se construyó el ciclo. Como resultado, se obtuvo un ciclo simple de conducción que puede servir de referencia para el análisis de consumo de combustible y diseño de estrategias para control de emisiones de automóviles bajo las condiciones de operación en la zona urbana de Pereira. En el ámbito del mismo proyecto, también se estudió la utilidad de la información recolectada, con herramientas de diagnóstico de bajo costo, durante la operación de los vehículos para propósitos de evaluación del desempeño de los motores

Experimental correlations for transient soot measurement in diesel exhaust aerosol with light extinction, electrical mobility and diffusion charger sensor techniques

A study of soot measurement deviation using a diffusion charger sensor with three dilution ratios was conducted in order to obtain an optimum setting that can be used to obtain accurate measurements in terms of soot mass emitted by a light-duty diesel engine under transient operating conditions. The paper includes three experimental phases: an experimental validation of the measurement settings in steady-state operating conditions; evaluation of the proposed setting under the New European Driving Cycle; and a study of correlations for different measurement techniques. These correlations provide a reliable tool for estimating soot emission from light extinction measurement or from accumulation particle mode concentration. There are several methods and correlations to estimate soot concentration in the literature but most of them were assessed for steady-state operating points. In this case, the correlations are obtained by more than 4000 points measured in transient conditions. The results of the new two correlations, with less than 4% deviation from the reference measurement, are presented in this paper.Bermúdez, V.; Pastor Soriano, JV.; López, JJ.; Campos, D. (2014). Experimental correlations for transient soot measurement in diesel exhaust aerosol with light extinction, electrical mobility and diffusion charger sensor techniques. Measurement Science and Technology. 25(6):1-13. doi:10.1088/0957-0233/25/6/065204S113256Davidson, C. I., Phalen, R. F., & Solomon, P. A. (2005). Airborne Particulate Matter and Human Health: A Review. Aerosol Science and Technology, 39(8), 737-749. doi:10.1080/02786820500191348Pope, C. A., Bates, D. V., & Raizenne, M. E. (1995). Health effects of particulate air pollution: time for reassessment? Environmental Health Perspectives, 103(5), 472-480. doi:10.1289/ehp.95103472Giechaskiel, B., Dilara, P., Sandbach, E., & Andersson, J. (2008). Particle measurement programme (PMP) light-duty inter-laboratory exercise: comparison of different particle number measurement systems. Measurement Science and Technology, 19(9), 095401. doi:10.1088/0957-0233/19/9/095401Park, K., Kittelson, D. B., & McMurry, P. H. (2004). Structural Properties of Diesel Exhaust Particles Measured by Transmission Electron Microscopy (TEM): Relationships to Particle Mass and Mobility. Aerosol Science and Technology, 38(9), 881-889. doi:10.1080/027868290505189LUO, C.-H., LEE, W.-M., & LIAW, J.-J. (2009). Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer. Journal of Environmental Sciences, 21(4), 452-457. doi:10.1016/s1001-0742(08)62291-3Matti Maricq, M. (2007). Chemical characterization of particulate emissions from diesel engines: A review. Journal of Aerosol Science, 38(11), 1079-1118. doi:10.1016/j.jaerosci.2007.08.001Smith, O. I. (1981). Fundamentals of soot formation in flames with application to diesel engine particulate emissions. Progress in Energy and Combustion Science, 7(4), 275-291. doi:10.1016/0360-1285(81)90002-2Haynes, B. S., & Wagner, H. G. (1981). Soot formation. Progress in Energy and Combustion Science, 7(4), 229-273. doi:10.1016/0360-1285(81)90001-0Bockhorn, H. (Ed.). (1994). Soot Formation in Combustion. Springer Series in Chemical Physics. doi:10.1007/978-3-642-85167-4Tree, D. R., & Svensson, K. I. (2007). Soot processes in compression ignition engines. Progress in Energy and Combustion Science, 33(3), 272-309. doi:10.1016/j.pecs.2006.03.002Kennedy, I. M. (1997). Models of soot formation and oxidation. Progress in Energy and Combustion Science, 23(2), 95-132. doi:10.1016/s0360-1285(97)00007-5Buonanno, G., Dell’Isola, M., Stabile, L., & Viola, A. (2011). Critical aspects of the uncertainty budget in the gravimetric PM measurements. Measurement, 44(1), 139-147. doi:10.1016/j.measurement.2010.09.037Symonds, J. P. R., Reavell, K. S. J., Olfert, J. S., Campbell, B. W., & Swift, S. J. (2007). Diesel soot mass calculation in real-time with a differential mobility spectrometer. Journal of Aerosol Science, 38(1), 52-68. doi:10.1016/j.jaerosci.2006.10.001Luque de Castro, M. D., & Priego-Capote, F. (2010). Soxhlet extraction: Past and present panacea. Journal of Chromatography A, 1217(16), 2383-2389. doi:10.1016/j.chroma.2009.11.027Wang, S. C., & Flagan, R. C. (1990). Scanning Electrical Mobility Spectrometer. Aerosol Science and Technology, 13(2), 230-240. doi:10.1080/02786829008959441Snegirev, A. Y., Makhviladze, G. ., & Roberts, J. . (2001). The effect of particle coagulation and fractal structure on the optical properties and detection of smoke. Fire Safety Journal, 36(1), 73-95. doi:10.1016/s0379-7112(00)00037-0Zhou, Z.-Q., Ahmed, T. U., & Y. Choi, M. (1998). Measurement of dimensionless soot extinction constant using a gravimetric sampling technique. Experimental Thermal and Fluid Science, 18(1), 27-32. doi:10.1016/s0894-1777(98)10005-5Arregle, J., Bermúdez, V., Serrano, J. R., & Fuentes, E. (2006). Procedure for engine transient cycle emissions testing in real time. Experimental Thermal and Fluid Science, 30(5), 485-496. doi:10.1016/j.expthermflusci.2005.10.002Bermúdez, V., Luján, J. M., Serrano, J. R., & Pla, B. (2008). Transient particle emission measurement with optical techniques. Measurement Science and Technology, 19(6), 065404. doi:10.1088/0957-0233/19/6/065404Giechaskiel, B., Maricq, M., Ntziachristos, L., Dardiotis, C., Wang, X., Axmann, H., … Schindler, W. (2014). Review of motor vehicle particulate emissions sampling and measurement: From smoke and filter mass to particle number. Journal of Aerosol Science, 67, 48-86. doi:10.1016/j.jaerosci.2013.09.003Lapuerta, M., Armas, O., & Gómez, A. (2003). Diesel Particle Size Distribution Estimation from Digital Image Analysis. Aerosol Science and Technology, 37(4), 369-381. doi:10.1080/02786820300970Desantes, J. M., Bermúdez, V., Molina, S., & Linares, W. G. (2011). Methodology for measuring exhaust aerosol size distributions using an engine test under transient operating conditions. Measurement Science and Technology, 22(11), 115101. doi:10.1088/0957-0233/22/11/115101Roessler, D. M. (1982). Diesel particle mass concentration by optical techniques. Applied Optics, 21(22), 4077. doi:10.1364/ao.21.004077Park, D., Kim, S., An, M., & Hwang, J. (2007). Real-time measurement of submicron aerosol particles having a log-normal size distribution by simultaneously using unipolar diffusion charger and unipolar field charger. Journal of Aerosol Science, 38(12), 1240-1245. doi:10.1016/j.jaerosci.2007.09.00

Modelling, Simulation And Speed Control Of Electric Vehicle

This thesis presents a simulation of an Electric Vehicle using MATLAB-Simulink software. The simulation is made by utilizing a 5 degree of fr dom (5-DOF) vehicle longitudinal model and a brushless direct current motor (BLDC) as the electric power train system In order to strengthen the study and to enhance the reliability of the results, validation was made to the 5-DOF vehicle model by adopting several vehicle behaviours and characteristics of Proton Iswara used by previous researchers. The validation tests performed in this study are acceleration then braking tests at 40 and 60 km/h, while the parameters are vehicle speed, tire longitudinal slip and wheel speed of the vehicle. By using the validated vehicle model and the electric power train system, a nonlinear-proportional integral controller was designed for the electric vehicle speed control. Several simulation tests were performed by employing the same reference speed as the vehicle validation and another reference speed proposed by Society of Automotive Engineer (SAE), namely the New European Driving Cycle (NEDC) and Worldwide Harmonised Light Vehicle Test Procedure (WLTP). Finally, the potential benefits of the proposed EV system together with the proposed speed control method were investigated. The speed control of the proposed system with an appropriate controller was demonstrated to be very promising

On the Impact of Particulate Matter Distribution on Pressure Drop of Wall-Flow Particulate Filters

[EN] Wall-flow particulate filters are a required exhaust aftertreatment system to abate particulate matter emissions and meet current and incoming regulations applying worldwide to new generations of diesel and gasoline internal combustion engines. Despite the high filtration efficiency covering the whole range of emitted particle sizes, the porous substrate constitutes a flow restriction especially relevant as particulate matter, both soot and ash, is collected. The dependence of the resulting pressure drop, and hence the fuel consumption penalty, on the particulate matter distribution along the inlet channels is discussed in this paper taking as reference experimental data obtained in water injection tests before the particulate filter. This technique is demonstrated to reduce the particulate filter pressure drop without negative effects on filtration performance. In order to justify these experimental data, the characteristics of the particulate layer are diagnosed applying modeling techniques. Different soot mass distributions along the inlet channels are analyzed combined with porosity change to assess the new properties after water injection. Their influence on the subsequent soot loading process and regeneration is assessed. The results evidence the main mechanisms of the water injection at the filter inlet to reduce pressure drop and boost the interest for control strategies able to force the re-entrainment of most of the particulate matter towards the inlet channels' end.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness through Grant No. TRA2016-79185-R. Additionally, the Ph.D. student Enrique Jose Sanchis has been funded by a grant from Universitat Politecnica de Valencia with the reference FPI-2016-S2-1355.Bermúdez, V.; Serrano, J.; Piqueras, P.; Sanchis-Pacheco, EJ. (2017). On the Impact of Particulate Matter Distribution on Pressure Drop of Wall-Flow Particulate Filters. Applied Sciences. 7(3):1-21. https://doi.org/10.3390/app7030234S12173Johnson, T. V. (2015). Review of Vehicular Emissions Trends. SAE International Journal of Engines, 8(3), 1152-1167. doi:10.4271/2015-01-0993Bermúdez, V., Serrano, J. R., Piqueras, P., & García-Afonso, O. (2011). Assessment by means of gas dynamic modelling of a pre-turbo diesel particulate filter configuration in a turbocharged HSDI diesel engine under full-load transient operation. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 225(9), 1134-1155. doi:10.1177/0954407011402278Subramaniam, M. N., Joergl, V., Keller, P., Weber, O., Toyoshima, T., & Vogt, C. D. (2009). Feasibility Assessment of a Pre-turbo After-Treatment System with a 1D Modeling Approach. SAE Technical Paper Series. doi:10.4271/2009-01-1276Luján, J. M., Bermúdez, V., Piqueras, P., & García-Afonso, Ó. (2015). Experimental assessment of pre-turbo aftertreatment configurations in a single stage turbocharged diesel engine. Part 1: Steady-state operation. Energy, 80, 599-613. doi:10.1016/j.energy.2014.05.048Luján, J. M., Serrano, J. R., Piqueras, P., & García-Afonso, Ó. (2015). Experimental assessment of a pre-turbo aftertreatment configuration in a single stage turbocharged diesel engine. Part 2: Transient operation. Energy, 80, 614-627. doi:10.1016/j.energy.2014.12.017Lee, J. H., Paratore, M. J., & Brown, D. B. (2008). Evaluation of Cu-Based SCR/DPF Technology for Diesel Exhaust Emission Control. SAE International Journal of Fuels and Lubricants, 1(1), 96-101. doi:10.4271/2008-01-0072Watling, T. C., Ravenscroft, M. R., & Avery, G. (2012). Development, validation and application of a model for an SCR catalyst coated diesel particulate filter. Catalysis Today, 188(1), 32-41. doi:10.1016/j.cattod.2012.02.007Marchitti, F., Nova, I., & Tronconi, E. (2016). Experimental study of the interaction between soot combustion and NH3-SCR reactivity over a Cu–Zeolite SDPF catalyst. Catalysis Today, 267, 110-118. doi:10.1016/j.cattod.2016.01.027Konstandopoulos, A. G., & Kostoglou, M. (2014). Analysis of Asymmetric and Variable Cell Geometry Wall-Flow Particulate Filters. SAE International Journal of Fuels and Lubricants, 7(2), 489-495. doi:10.4271/2014-01-1510Bollerhoff, T., Markomanolakis, I., & Koltsakis, G. (2012). Filtration and regeneration modeling for particulate filters with inhomogeneous wall structure. Catalysis Today, 188(1), 24-31. doi:10.1016/j.cattod.2011.12.017Iwata, H., Konstandopoulos, A., Nakamura, K., Ogiso, A., Ogyu, K., Shibata, T., & Ohno, K. (2015). Further Experimental Study of Asymmetric Plugging Layout on DPFs: Effect of Wall Thickness on Pressure Drop and Soot Oxidation. SAE Technical Paper Series. doi:10.4271/2015-01-1016Bermúdez, V., Serrano, J. R., Piqueras, P., & García-Afonso, O. (2015). Pre-DPF water injection technique for pressure drop control in loaded wall-flow diesel particulate filters. Applied Energy, 140, 234-245. doi:10.1016/j.apenergy.2014.12.003Serrano, J. R., Bermudez, V., Piqueras, P., & Angiolini, E. (2015). Application of Pre-DPF Water Injection Technique for Pressure Drop Limitation. SAE Technical Paper Series. doi:10.4271/2015-01-0985Wang, Y., Wong, V., Sappok, A., & Munnis, S. (2013). The Sensitivity of DPF Performance to the Spatial Distribution of Ash Inside DPF Inlet Channels. SAE Technical Paper Series. doi:10.4271/2013-01-1584Sappok, A., Govani, I., Kamp, C., Wang, Y., & Wong, V. (2013). In-Situ Optical Analysis of Ash Formation and Transport in Diesel Particulate Filters During Active and Passive DPF Regeneration Processes. SAE International Journal of Fuels and Lubricants, 6(2), 336-349. doi:10.4271/2013-01-0519Torregrosa, A. J., Serrano, J. R., Arnau, F. J., & Piqueras, P. (2011). A fluid dynamic model for unsteady compressible flow in wall-flow diesel particulate filters. Energy, 36(1), 671-684. doi:10.1016/j.energy.2010.09.047CMT-Motores Tèrmicos (Universitat Politècnica de València)www.openwam.orgLax, P. D., & Wendroff, B. (1964). Difference schemes for hyperbolic equations with high order of accuracy. Communications on Pure and Applied Mathematics, 17(3), 381-398. doi:10.1002/cpa.3160170311Serrano, J. R., Arnau, F. J., Piqueras, P., & García-Afonso, O. (2013). Application of the two-step Lax and Wendroff FCT and the CE-SE method to flow transport in wall-flow monoliths. International Journal of Computer Mathematics, 91(1), 71-84. doi:10.1080/00207160.2013.783206Desantes, J. M., Serrano, J. R., Arnau, F. J., & Piqueras, P. (2012). Derivation of the method of characteristics for the fluid dynamic solution of flow advection along porous wall channels. Applied Mathematical Modelling, 36(7), 3134-3152. doi:10.1016/j.apm.2011.09.090Serrano, J. R., Arnau, F. J., Piqueras, P., & García-Afonso, Ó. (2013). Packed bed of spherical particles approach for pressure drop prediction in wall-flow DPFs (diesel particulate filters) under soot loading conditions. Energy, 58, 644-654. doi:10.1016/j.energy.2013.05.051Murtagh, M. J., Sherwood, D. L., & Socha, L. S. (1994). Development of a Diesel Particulate Filter Composition and Its Effect on Thermal Durability and Filtration Performance. SAE Technical Paper Series. doi:10.4271/940235Fino, D., Russo, N., Millo, F., Vezza, D. S., Ferrero, F., & Chianale, A. (2009). New Tool for Experimental Analysis of Diesel Particulate Filter Loading. Topics in Catalysis, 52(13-20), 2083-2087. doi:10.1007/s11244-009-9393-zKonstandopoulos, A. G., & Johnson, J. H. (1989). Wall-Flow Diesel Particulate Filters—Their Pressure Drop and Collection Efficiency. SAE Technical Paper Series. doi:10.4271/890405Lapuerta, M., Ballesteros, R., & Martos, F. J. (2006). A method to determine the fractal dimension of diesel soot agglomerates. Journal of Colloid and Interface Science, 303(1), 149-158. doi:10.1016/j.jcis.2006.07.066Serrano, J. R., Climent, H., Piqueras, P., & Angiolini, E. (2016). Filtration modelling in wall-flow particulate filters of low soot penetration thickness. Energy, 112, 883-898. doi:10.1016/j.energy.2016.06.121Logan, B. E., Jewett, D. G., Arnold, R. G., Bouwer, E. J., & O’Melia, C. R. (1995). Clarification of Clean-Bed Filtration Models. Journal of Environmental Engineering, 121(12), 869-873. doi:10.1061/(asce)0733-9372(1995)121:12(869)Koltsakis, G. C., & Stamatelos, A. M. (1997). Modes of Catalytic Regeneration in Diesel Particulate Filters. Industrial & Engineering Chemistry Research, 36(10), 4155-4165. doi:10.1021/ie970095mBissett, E. J. (1984). Mathematical model of the thermal regeneration of a wall-flow monolith diesel particulate filter. Chemical Engineering Science, 39(7-8), 1233-1244. doi:10.1016/0009-2509(84)85084-8Galindo, J., Serrano, J. R., Piqueras, P., & García-Afonso, Ó. (2012). Heat transfer modelling in honeycomb wall-flow diesel particulate filters. Energy, 43(1), 201-213. doi:10.1016/j.energy.2012.04.044Payri, F., Broatch, A., Serrano, J. R., & Piqueras, P. (2011). Experimental–theoretical methodology for determination of inertial pressure drop distribution and pore structure properties in wall-flow diesel particulate filters (DPFs). Energy, 36(12), 6731-6744. doi:10.1016/j.energy.2011.10.033Konstandopoulos, A. G., Skaperdas, E., & Masoudi, M. (2002). Microstructural Properties of Soot Deposits in Diesel Particulate Traps. SAE Technical Paper Series. doi:10.4271/2002-01-1015Bermúdez, V., Serrano, J. R., Piqueras, P., & Campos, D. (2015). Analysis of the influence of pre-DPF water injection technique on pollutants emission. Energy, 89, 778-792. doi:10.1016/j.energy.2015.05.14

Design of Variable Geometry Waste Heat Recovery Turbine for High Efficiency Internal Combustion Engine

This study was carried out for a 1.25L Zetec-SE DOHC engine model but its application is generic to gasoline engine (light-duty engine) applications. An ORC model with a radial turbine sub-model is implemented in a light-duty gasoline I.C engine model, to evaluate the impact of the ORC with VGT on the engine fuel consumption, net power output and finally the ORC system efficiency as compared to ORC with FGT. The results showed that VGT can improve ORC system efficiency and net power output by an unweighted point of 5.6% and 3.07kW respectively at partial to high load conditions while benefits are even higher at the lower loads therefore making it an attractive technology given its ability to recover low-grade heat and the possibility to be implemented in decentralized lower-capacity power plant

Realization of a dual clutch transmission hydraulic and thermal model for HIL applications

Depleting oil resources and global warming has led to a continual search in the automotive field to find a cost-effective solution to develop more and more fuel efficient vehicles. In the last years the number of electric and hybrid vehicles have rapidly increase thanks to pollution standards and their high efficiency. It is possible to define three main categories, based mainly on the power of the electric motor and the capacity of the batteries. In "mild" hybrids, a small unit takes the place of the alternator and starter motor, and is connected to the main engine with a belt. When it slows down, it recharges a battery, while the energy flow is reversed, and the current motor "helps" the thermal one. The "full" hybrids have instead more powerful electric motors that are integrated with the rest of the vehicles : they are often part of the transmission. The "plug-ins" are "full" equipped with much larger batteries, which allow a range of tens of kilometers without using fuel; to be able to charge them to the maximum, however, it is necessary to connect them to the electric network through a cable. Otherwise, these cars behave like "full" hybrids: the accumulators are filled by the inertia of the vehicle when it slows down. As a result of this, new concepts called hybrid dual clutch transmission (HDCT) have been developed. These new type of transmission are suitable for multiple hybridisation topologies, as the e-machine can be connected to the transmission by different methods in order to obtain a more efficient interaction of the internal combustion engine and the e-machine. Compared to an automatic transmission based on planetary gearsets or to continuous variable transmissions (CVT), further optimisation potentials can be achieved thanks to the flexible hybridisation concept. This thesis aims to realize a model to calculate the heat generated by an hybrid dual clutch transmission in real-time without a great amount of computing power

Computational and experimental study of air hybrid engine concepts

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityThe air hybrid engine absorbs the vehicle kinetic energy during braking, stores it in an air tank in the form of compressed air, and reuses it to start the engine and to propel a vehicle during cruising and acceleration. Capturing, storing and reusing this braking energy to achieve stop-start operation and to give additional power can therefore improve fuel economy, particularly in cities and urban areas where the traffic conditions involve many stops and starts. In order to reuse the residual kinetic energy, the vehicle operation consists of 3 basic modes, i.e. Compression Mode (CM), Expander Mode (EM) and normal firing mode, as well as stop-start operation through an air starter. A four-cylinder 2 litre diesel engine has been modelled to operate in four air hybrid engine configurations so that the braking and motoring performance of each configuration could be studied. These air hybrid systems can be constructed with production technologies and incur minimum changes to the existing engine design. The regenerative engine braking and starting capability is realised through the employment of an innovative simple one-way intake system and a production cam profile switching (CPS) mechanism. The hybrid systems will allow the engine to be cranked by the compressed air at moderate pressure without using addition starters or dedicated valves in the cylinder head. Therefore, the proposed air hybrid engine systems can be considered as a cost-effective regenerative hybrid powertrain and can be implemented in vehicles using existing production technologies. A novel cost-effective pneumatic regenerative stop-start hybrid system, Regenerative Engine Braking Device (RegenEBD), for buses and commercial vehicles is presented. RegenEBD is capable of converting kinetic energy into pneumatic energy in the compressed air saved in an air tank using a production engine braking device and other production type automotive components and a proprietary intake system design. The compressed air is then used to drive an air starter to achieve regenerative stop-start operations. The proposed hybrid system can work with the existing vehicle transmission system and can be implemented with the retro-fitted valve actuation device and a sandwich block mounted between the cylinder head and the production intake manifold. Compression mode operation is achieved by keeping the intake valves from fully closed throughout the four-strokes through a production type variable valve exhaust brake (VVEB) device on the intake valves. As a result, the induced air could be compressed through the opening gap of intake valves into the air tank through the intake system of proprietary design. The compressed air can then be used to crank the engine directly through the air expander operation or indirectly through the action of an air starter in production. A single cylinder camless engine has been set up and operated to evaluate the compression mode performance of two air hybrid concepts. The experimental results are then compared with the computational output with excellent agreement. In order to evaluate the potential of the air hybrid engine technologies, a new vehicle driving cycle simulation program has been developed using Matlab Simulink. An air hybrid engine sub-model and methodology for modelling the air hybrid engine’s performance have been proposed and implemented in the vehicle driving cycle simulation. The NEDC analysis of a Ford Mondeo vehicle shows that the vehicle can achieve regenerative stop-start operations throughout the driving cycle when it is powered by a 2.0litre diesel engine with air hybrid operation using a 40litre air tank of less than 10bar pressure. The regenerative stop-start operation can lead to 4.5% fuel saving during the NEDC. Finally, the Millbrook London Transport Bus (MLTB) driving cycle has been used to analyse the effectiveness of RegenEBD on a double deck bus powered by a Yuchai diesel engine. The results show that 90% stop-starts during the MLTB can be accomplished by RegenEBD and that a significant fuel saving of 6.5% can be obtained from the regenerative stop-start operations