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Over the last decades, a tremendous effort has been made by the European Commission to control the amount of pollution in urban areas by means of EC directives to limit emissions. Today one of the main problems in urban areas is the particulate matter, predominantly emitted by diesel engines. ...In this scenario, the research group of the University of Rome “Tor Vergata” has undertaken a research project with the aim of identifying the benefits of new drive system technologies for urban buses. In this work, the potential benefits of replacing Diesel engines with two different hybrid powertrains are shown. ...To obtain a projection of the beneficial effects of the hybridization on the urban area of Rome, numerical simulations have been carried out on some “real” driving cycles corresponding to real bus routes.

The number of miles traveled per gallon of fuel consumed in High Prformance Urban Route Cycle by a heavy urban bus or by a light school bus are increased by a factor of about three.

The dual-fuel operation of a Melbourne urban bus, with turbo-charged diesel engine, using CNG is investigated. Extensive instrumented engine testing established the upper limit to diesel fuel substitution at 90%.

A hybrid bus powered by a diesel engine and a battery pack has been analyzed over an idealized bus-driving cycle in Chicago. Three hybrid configurations, two parallel and one series, have been evaluated. The results indicate that the fuel economy of a hybrid bus, taking into account the regenerative braking, is comparable with that of a conventional diesel bus. Life-cycle costs are slightly higher because of the added weight and cost of the battery.

The role of Spark Ignition (SI) and Diesel engines as nanoparticles sources in urban area was investigated. Detection, sizing and counting of particles were realized at the exhaust of a Port Fuel Injection Spark Ignition (PFI SI) engine equipped with a Three-Way Catalyst (TWC) and a Unijet Common Rail (CR) Diesel engine equipped first with an Oxidation Catalyst (OC) and then with a Catalyzed Diesel Particulate Filter (CDPF).

This has made that lot's of cities have decided to use CNG as an alternative fuel in their urban transport fleets or in other urban tasks. Nevertheless, due to the recent implementation of the CNG technology in automotive sector, several problems related to lubrication have been detected, mostly affecting a reduction of the oil drain period and these problems showed no relationship with a particular fleet nor with the lubricant's brand used. ...In this study, a representative sample of urban buses, powered with different CNG and Diesel engine technologies and working on urban duty operation, have been studied in a comparative way in order to evaluate engine oil performance differences.

The current work presents the results of an investigation on the impact of renewable fuels on the combustion and emissions of a turbocharged compression-ignition internal combustion engine. An experimental study was undertaken and the engine settings were not modified to account for the fuel's chemical and physical properties, to analyze the performance of the fuel as a potential drop-in alternative fuel. Three fuels were tested: mineral diesel, a blend of it with waste cooking oil biodiesel and a hydrogenated diesel. The analysis of the emissions at engine exhaust highlights that hydrogenated fuel allows to reduce CO, total hydrocarbon emissions, particulate matter and NOx.

Fuel consumption and emissions were estimated for comparable gasoline and diesel light-duty hybrid electric vehicles operating over single and multiple urban drive cycles. Comparisons between the gasoline and diesel vehicle fuel consumptions and emissions were used to identify potential advantages and technical barriers for diesel hybrids.

Particulate emission from diesel engines is one of the most important pollutants in urban areas. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US.

In order to study the coupling effects of biodiesel blend and CCRT (Catalyzed Continuously Regeneration Trap) on the particulate matter emissions, the particulate matter emissions from an urban bus with and without CCRT burning BD0 and BD10 respectively was tested and analyzed using electrical low pressure impactor (ELPI).

Progress is reported on a project sponsored by the California Air Resources Board (ARB) to evaluate the potential of diesel particulate trap systems for retrofit application to reduce emissions from buses and trucks. A trap system was selected for evaluation based on availability of commercial prototypes at the time of the project. Engine dynamometer testing of this trap system is reported over advanced design bus cycles. The results showed that the system is viable for application to a bus equipped with a Detroit Diesel Corporation 6V-92TA diesel engine, producing satisfactory exhaust backpressure and emission characteristics over a 500 hour test period. Field testing of this system on a transit coach is now ongoing at Southern California Rapid Transit District (SCRTD) and the experience is reported. Emission testing has been conducted regularly at ARB to verify the performance of the trap system.

Progress is reported on a project to evaluate the potential of diesel particulate trap systems for retrofit application to reduce emissions from buses and trucks in the State of California. A trap system was selected for evaluation, based on availability of commercial prototypes at the time of the project. Engine dynamometer testing of this trap system is reported over advanced design bus cycles. The results showed that the system is viable for application to a bus equipped with a Detroit Diesel Corporation 6V-92TA diesel engine, producing satisfactory exhaust backpressure and emission characteristics over a 500 hour test period. Work is now proceeding on field testing of this system on a transit coach, and engine dynamometer and field testing of a similar system on a truck equipped with a Cummins NTC 350 diesel engine.

In urban areas, particulate emission from Diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus Diesel engines using particulate filter technology is being introducing in La Rochelle. ...As a result, particulate emission control from urban bus Diesel engines using particulate filter technology is being introducing in La Rochelle. ...The Diesel Particulate Filter (DPF) introduction on the existing urban bus fleet has been initiated by the CDA La Rochelle through a voluntary retrofit program.

In urban areas, particulate emission from diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US. ...As a result, particulate emission control from urban bus diesel engines using particle filter technology is being evaluated at several locations in the US.

Soot and ash accumulation data are reported comparing two aggressive driving cycles (Artemis Urban vs. Artemis Motorway). Each cycle was operated for 20k km on a dynamic engine bench. PN emissions were then measured over WLTC and NEDC test cycles after 20k km. ...In particular the Artemis Urban cycle shows higher ash amount over 20k km (1.26 g/l) compared to the Artemis Motorway (0.4 g/l).

The goal of this project was to determine the exhaust mass emissions of light duty trucks (LDT) with three different engine concepts under real world conditions in the urban area of Vienna. Therefore three identical GM Opel Combo LDT with 1.6 liter monovalent CNG S.I. engine, 1.7 liter common rail turbo charged diesel engine and 1.4 liter Ecotec gasoline S.I. engine were tested systematically on representative urban routes and in parcel service. ...Therefore three identical GM Opel Combo LDT with 1.6 liter monovalent CNG S.I. engine, 1.7 liter common rail turbo charged diesel engine and 1.4 liter Ecotec gasoline S.I. engine were tested systematically on representative urban routes and in parcel service. All engines corresponded to the new Euro IV emission standard and were within the same power range.

Performance and power measurements have been taken from demonstrations at several typical urban center city bus service operations. From test results detailed in this paper, it is shown that the electric bus obtains 11.5 miles/gal of fuel compared to 3.5 and 6.0 miles/gal for equivalent sized gasoline and diesel engine buses in similar urban transit service. ...From test results detailed in this paper, it is shown that the electric bus obtains 11.5 miles/gal of fuel compared to 3.5 and 6.0 miles/gal for equivalent sized gasoline and diesel engine buses in similar urban transit service.

Each driving style is tested on three road types: urban, rural and motorway. Consumption+CO2 is highest on urban roads for all driving styles except for the Toyota Prius where this is only valid for the aggressive style; it is lowest on rural roads except for aggressive driving that is lowest on motorway for the Peugeot 307 petrol and diesel. ...The lowest increase is for the Seat Leon LPG (9% urban and 19% rural) together with the Prius (18% rural). Aggressive driving on urban roads results in high absolute consumption and CO2 figures of 10 to 18 l/100km and 240 to 430 g/km (Toyota Prius and Peugeot 307 petrol respectively). ...There is little difference between the new, relaxed and normal style; the relaxed one gives overall the lowest results with a largest difference to normal style of 20% for the Prius and Peugeot diesel on urban roads. The Prius has the lowest consumption on urban and rural roads and the Peugeot 307 diesel is lowest on the motorway.

The main reason for the utilization of methane gas, in the form of natural gas or purified biogas, is as substitute of the diesel oil, aiming to the reduction of the pollution by the exhaust gases from the combustion engines of the urban buses. The largest pollutants of diesel engines are the particulates, originated by the combustion process, and the sulphur oxides. ...As the natural gas is free from sulphur, and the spark ignition cycle does not originate particulates, these are obvious advantages of the utilization of the methane as fuel in the urban vehicles. But the spark ignition engines burning methane originates much more NOx, nearly twice as much, than the diesel engine equivalent, particularly at high loads.

In urban traffic vehicle use leads to running conditions which vary essentially according to torque and speed.