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Preliminary experimental evaluation of a four wheel motors, batteries plus ultracapacitors and series hybrid powertrain
No full textThis paper reports the preliminary experimental evaluation of a four wheel motors series hybrid prototype equipped with an internal combustion engine coupled to a generator and an energy recovery system (batteries plus ultracapacitors) The paper analyses global efficiency (energy dissipated to overcome the dissipative forces on energy dissipated in fuel) autonomy in electric configuration and the efficiency of the regenerative braking system The tests were carried out in a test cell equipped with a chassis dynamometer The tests were performed according to the current regulated procedures A constant speed test was performed in order to evaluate the autonomy of the vehicle in the electric configuration The results show that the real tank to wheels efficiency is about 30% for HOST as a series hybrid and 79% for HOST as an electric vehicle
Innovative design of an hydrogen powertrain via reverse engineering
No full textIn this paper the powertrain of a zero emission vehicle powered by hydrogen has been designed with an innovative approach via reverse engineering. The use of a zero environmental impact vehicles is particularly stringent in urban area where high air pollutant concentrations could be reached. In particular, in this paper, the use of fuel cell vehicles plus ultracapacitors has been considered to minimize the TTW (Tank to Wheels) global efficiency in comparison with the conventional vehicles powered by ICE. A zero emissions city-car is designed by optimization of the components (in particular the energy storage) in order to minimize both its weight and its bulk with particular reference to the functions (passenger vehicles, minibus, freight distribution), the areas where the vehicle is driven (characteristic drive cycles, traffic) and the users (different driving style). In particular the design discussed in this paper was carried out through a process of reverse engineering. The energy needs, in fact, were calculated starting from real drive cycles obtained during an on-board data acquisition campaign carried out in Rome urban area. In this paper the powertrain is designed starting from the acquisition of real drive cycles obtained during acquisitions campaign in an urban area. The data collected by the on-board acquisitions systems has been used to evaluate the power required by the wheels as a function of time in a generic urban drive cycle and the energy needs of an urban vehicle. Thus, the analysis performed takes into account not only global energy consumption, but also the power needs that are affected by both the congested traffic conditions and the driving style. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved
Energetic evaluation on auxiliary systems of an hydrogen hybrid minibus
No full textThe transport is currently shifting towards an electric hybridization of the powertrain and the primary target is to decrease the pollutant emissions, to enhance efficiency and contemporary maintain the current vehicle performances. In particular the range is crucial for the electric powertrain and it could be sensitively affected by the auxiliary systems consumption. In fact it represents a considerable load and its consumption could reach 34% of total energy in a vehicle as verified in this work. The carried out activity has dealt with the energy analysis of the bus in different cases study varying the number of passengers, to evaluate the real range of the vehicle in real conditions. After that, the analysis has delved to the auxiliary system of mini-buses consisting of APU (Auxiliary Power Unit), suspension air compressor, cooling fans, water pump, windscreen wiper, doors motion, lights, defrosting device, electronic management system, power steering, power braking system. Once set up different representative working parameters, the data has been acquired during real tests performed to evaluate the energy required by each device. They have been exploited to simulate the auxiliary energy incidence on the actual range of the bus in real use. The auxiliary system incidences have been evaluated on the global efficiency of the minibus monitoring the energy use of auxiliary components by developing an efficient data acquisition system. The conclusion is that the energy required by the auxiliaries is not negligible, so that the efficiency enhancement of the auxiliaries could lead through an improvement of the global energy use in the vehicle, which is particularly important for innovative means of transport which are characterized by a limited range, as the electric and the hydrogen vehicle
Utilizzo dei dati provenienti dalla diagnostica dei veicoli per il calcolo dei consumi e della CO2
No full textNumerose pubblicazioni scientifiche hanno dimostrato che le prestazioni energetico-emissive dei veicoli nelle prove standard di omologazione non sono fedeli alle reali prestazioni su strada, poiché esse sono influenzate da condizioni esterne variabili e difficilmente riproducibili al banco a rulli come lo stile di guida del conducente e le condizioni del traffico. Nell’ambito del progetto PEGASUS, un progetto di innovazione industriale per la mobilità sostenibile che fa capo al programma INDUSTRIA 2015, è stata eseguita una campagna di acquisizione su strada per il monitoraggio dell’impatto energetico ambientale di 10 veicoli, 4 del servizio Car-Sharing di Roma e 6 del Car Rental di AVIS. I veicoli sono stati monitorati con dei pc di bordo di tipo automotive in grado di acquisire sia i dati GPS sia i dati provenienti dal sistema elettronico del veicolo tramite la presa di diagnosi OBD: dati quali la velocità del veicolo, regime rotazione motore, posizione del pedale dell’acceleratore, carico motore, portata d’aria aspirata, tensione della sonda lambda, etc, sono stati acquisiti con un rate di 2 hertz. L’obiettivo del presente lavoro è quello di calibrare e validare dei modelli di consumo di carburante e di produzione della CO2 per veicoli a benzina e diesel. Per validare i modelli i veicoli sono stati testati su un banco a rulli ed è stato installato un analizzatore per la misura dei gas di scarico (OBS Horiba 1300). I valori dei sensori installati sul motore sono stati confrontati con i valori misurati dall’analizzatore. Le prove necessarie per la calibrazione dei modelli sono risultate le seguenti: warm-up, idle, curva di potenza massima, prove a numero di giri costante e carico variabile
Sviluppo di una strategia di gestione energetica del motore a combustione interna di un veicolo ibrido serie
No full textSOMMARIO Questo lavoro parte da alcune semplici considerazioni: un motore a combustione interna, quando lavora a carichi variabili, ha rendimenti molto bassi; nella fase di warm-up le emissioni sono maggiori (motivo per cui non è indicato accendere e spegnere il motore frequentemente); un veicolo ibrido serie consente al motore a combustione interna di lavorare a punto fisso, la vita dei sistemi di stoccaggio elettrochimici diminuisce se alimentati da correnti impulsive. Inoltre, è noto che i veicoli ibrido-serie possono operare in diverse modalità, quali: 1) Modalità solo elettrica: il motore è spento ed il veicolo è alimentato unicamente dalle batterie. 2) Modalità solo termica: la trazione del veicolo viene assicurata dal solo motore a combustione interna accoppiato con il generatore elettrico, mentre le batterie non vengono ne ricaricate ne erogano corrente. 3) Modalità ibrida: la trazione viene assicurata sia dal motore a combustione interna accoppiata al generatore sia dalle batterie. 4) Modalità termica con ricarica delle batterie: la trazione viene assicurata dal motore a combustione interna accoppiato al generatore, che ricarica anche le batterie. 5) Modalità frenata rigenerativa: il motore a combustione interna è spento e il motore di trazione viene usato come generatore per ricaricare le batterie. 6) Modalità ricarica delle batterie: Il motore di trazione non è alimentato e il motore a combustione interna accoppiato al generatore ricarica le batterie.7) Modalità ibrida di ricarica delle batterie: sia il motore a combustione interna accoppiato al generatore che il motore di trazione (usato come generatore) ricaricano le batterie. Nel lavoro proposto, grazie ad un’attenta analisi di una serie di dati e mappature relative al motore Smart 0.8Cdi, viene definito inizialmente il punto di funzionamento ottimale del motore a combustione interna. L’analisi successiva viene compiuta su cicli reali, partendo quindi da cicli di marcia, acquisiti su percorsi cittadini, fino ad arrivare alla simulazione delle correnti erogate dalle batterie e dai supercondensatori. Infine attraverso opportune simulazioni energetico-emissive, viene definita una possibile Power Control Strategy (strategia di controllo dei flussi di potenza) di un ibrido serie, implementata per ottimizzare il sistema e cioè per minimizzare consumo di combustibile e emissioni e massimizzare la vita del sistema di stoccaggio. SVILUPPO DI UNA STRATEGIA DI GESTIONE ENERGETICA DEL MOTORE A COMBUSTIONE INTERNA DI UN VEICOLO IBRIDO SERIE Lorenzo Rambaldi1, Adriano Santiangeli2, Fabio Orecchini2, Vincenzo Naso1 1CIRPS - Centro di Ricerca Interuniversitario per lo Sviluppo Sostenibile - Sapienza Università di Roma Piazza San Pietro in Vincoli 10 – 00184 Roma 2Dipartimento di Meccanica ed Energetica - Università degli studi Guglielmo Marconi Via Plinio 44, – 00192 Roma SUMMARY This paper starts from some basic considerations: an internal combustion engine, when working with varying loads, has very low yields. During the warm-up emissions are higher; a series hybrid vehicle allows the internal combustion engine to work at a fixed point (permits exceeding the specified limit at the first point increasing the overall efficiency of the vehicle); state of health of electrochemical storage systems decreases if powered by inconstant current. Furthermore, it is known that series-hybrid vehicles can operate in different modes, such as: 1) Pure electric mode: the engine is off and the vehicle is powered only by batteries. 2) Pure ICE mode: the traction of the vehicle is provided only by an internal combustion engine coupled with the electric generator, while the batteries are neither recharged nor giving current. 3) Hybrid: the traction is ensured by both the internal combustion engine coupled to the generator and batteries. 4) Thermal mode with battery recharging: the traction is provided by the internal combustion engine coupled to the generator, which recharges the batteries. 5) Regenerative braking mode: the internal combustion engine is off and the traction engine is used as a generator to recharge the batteries. 6) Battery charging mode: the traction engine is not powered and the internal combustion engine coupled to the generator recharges the batteries. 7) Hybrid mode to recharge the batteries: both the internal combustion engine coupled to the generator that the traction engine (used as a generator) recharges the batteries. In the proposed work, thanks to a detailed analysis of a data set and mapping of the Smart 0.8Cdi engine is initially defined the optimal operating point of internal combustion engine including consideration of issues concerning the stability and stress induced. The subsequent analysis is performed on real cycles, starting from driving cycles developed on city routes, up to the simulation of the currents supplied by the batteries and ultracapacitors. Lastly, through appropriate energy-emissive simulations a possible Power Control Strategy (strategy monitoring flows of energy) of a series hybrid was obtained, implemented to optimize the system, to minimize fuel consumption and emissions and maximize the life of the storage system
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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