The 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.

[EN] The main objective of this doctoral thesis is the development of a comprehensive methodology to perform and analyse the thermal balance of reciprocating engines, based on experimental and theoretical techniques. Starting from previous works carried out in the research group, which are related to combustion diagnosis and thermal management, a methodology to analyse the thermal balance from two points of view was proposed: on the one hand, the external point of view, mainly based on experimental measurements, and on the other hand, the internal point of view, based on modelling. The combination of both approaches allows the necessary model adjustment, along with a detail characterization of the different energy flows. Apart from the thermal balance methodology, several proposals to model some internal processes have been provided, being noteworthy the sub-models for heat transfer to the chamber walls, the ports and between the oil and coolant. Besides, detailed mechanical losses model was also developed. With the aim of ensuring the models reliability and robustness, an integral uncertainty adjustment methodology is proposed, which allows determining some parameters affecting the thermodynamic properties within the chamber and the sub-models adjustment. The analysis and calibration methodology is flexible enough to be applied in different types of engines and combustion modes, thus ensuring its generality. To demonstrate the methodology potential, it is finally applied to analyse specific parametric studies in two engines, showing its usefulness for both diagnostic and predictive applications. / [ES] El objetivo principal de la presente tesis doctoral es el desarrollo de una metodología integral que permita analizar el balance de energía en motores de combustión interna alternativos, mediante la combinación de diferentes técnicas experimentales y teóricas. Para ello, partiendo de varios trabajos previos realizados en el grupo de investigación en temas relacionados con diagnóstico de la combustión y gestión térmica del motor, se ha propuesto una separación del análisis energético en dos puntos de vista: exterior, basado principalmente en medidas experimentales e interior, fundamentalmente basado en modelado. La combinación de ambos enfoques permite el necesario ajuste de los modelos, así como la caracterización completa y fiable de los flujos de energía en el motor. Junto a la metodología del balance energético, se han aportado una serie de propuestas para el modelado de diferentes procesos internos, entre los que destacan los modelos de transmisión de calor a las paredes de la cámara de combustión, a las pipas y entre el aceite y el refrigerante, así como un modelo detallado de pérdidas mecánicas. Con el fin de garantizar la robustez y fiabilidad de dichos modelos, se ha propuesto una metodología de ajuste de incertidumbres que permite obtener el valor de varios parámetros que afectan al cálculo de las condiciones termodinámicas en la cámara, así como el ajuste de los diferentes modelos propuestos. La metodología de análisis y calibración es suficientemente flexible para ser aplicada a motores de características y modos de combustión diferentes, asegurando así la generalidad de la herramienta. Para mostrar su potencial, se ha aplicado a dos motores en estudios paramétricos específicos, verificándose su utilidad como herramienta tanto de diagnóstico como para su uso en aplicaciones predictivas. / [CA] L'objectiu principal de la present tesi doctoral és el desenrotllament d'una metodologia integral que permeta analitzar el balanç d'energia en motors de combustió interna alternatius, per mitjà de la combinació de diferents tècniques experimentals i teòriques. Per a això, partint de diversos treballs previs realitzats en el grup d'investigació en temes relacionats amb diagnòstic de la combustió i gestió tèrmica del motor, s'ha proposat una separació de l'anàlisi energètica en dos punts de vista: exterior, basat principalment en mesures experimentals i interior, fonamentalment basat en modelatge. La combinació d'ambdós enfocaments permet el necessari ajust dels models, així com la caracterització detallada dels diferents fluxos energètics. Junt amb la metodologia del balanç energètic, s'han aportat una sèrie de propostes per al modelatge de diferents processos interns, entre els que destaquen els models de transmissió de calor a les parets de la cambra de combustió, a les pipes i entre l'oli i el refrigerant, així com un model detallat de pèrdues mecàniques. A fi de garantir la robustesa i fiabilitat dels dits models, s'ha proposat una metodologia integral d'ajust d'incerteses que permet obtindre el valor de diversos paràmetres que afecten el càlcul de les condicions termodinàmiques en la cambra, així com l'ajust dels diferents models proposats. La metodologia d'anàlisi i calibratge és prou flexible per a ser aplicada a motors de característiques i modes de combustió diferents, assegurant així la generalitat de la ferramenta. Per a mostrar el seu potencial, finalment s'ha aplicat a dos motors en estudis paramètrics específics, verificant la seua utilitat tant com a ferramenta de diagnòstic com en aplicacions predictives. / Carreño Arango, R. (2016). A comprehensive methodology to analyse the Global Energy Balance in Reciprocating Internal Combustion Engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/73069

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis proposes an artificial neural network (NN) model to predict fuel consumption in heavy vehicles. The model uses predictors derived from vehicle speed, mass, and road grade. These variables are readily available from telematics devices that are becoming an integral part of connected vehicles. The model predictors are aggregated over a fixed distance traveled (i.e., window) instead of fixed time interval. It was found that 1km windows is most appropriate for the vocations studied in this thesis. Two vocations were studied, refuse and delivery trucks. The proposed NN model was compared to two traditional models. The first is a parametric model similar to one found in the literature. The second is a linear regression model that uses the same features developed for the NN model. The confidence level of the models using these three methods were calculated in order to evaluate the models variances. It was found that the NN models produce lower point-wise error. However, the stability of the models are not as high as regression models. In order to improve the variance of the NN models, an ensemble based on the average of 5-fold models was created. Finally, the confidence level of each model is analyzed in order to understand how much error is expected from each model. The mean training error was used to correct the ensemble predictions for five K-Fold models. The ensemble K-fold model predictions are more reliable than the single NN and has lower confidence interval than both the parametric and regression models.