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Technical Paper

The Composition of Gasoline Engine Hydrocarbon Emissions - An Evaluation of Catalyst and Fuel Effects

1990-10-01
902074
Twenty-three hydrocarbon components were analysed in the exhaust emissions from a 2.3 litre gasoline engine. The effect of a three-way catalyst on emission rates was investigated, as was the effect of addition to fuel of specific aromatic and olefinic compounds. The addition of 1-hexene and 1-octene (olefins) caused statistically significant increases in reactive olefins - ethene and propene - in the exhaust. The addition of benzene and toluene led to increases in these compounds in the exhaust, and indicated that whilst fuel-toluene is the main source of toluene emissions, the emission of benzene has sources in addition to fuel-benzene. A three-way catalyst, when operating at > 600°C, eliminated most hydrocarbons except methane and traces of the light aromatics. At idle, however, the catalyst exhibited substantial selectivity towards different hydrocarbons according to their ease-of-oxidation.
Technical Paper

Injection Timing and Rate Control - A Solution for Low Emissions

1990-02-01
900854
This paper describes latest results from the Ricardo heavy duty diesel engine research programme. Using a Diesel Kiki P-TICS II injection system, matched to a low swirl combustion chamber, emission results well within the US 1991 engineering targets have been achieved with good fuel economy. Very low NOx levels have also been demonstrated whilst maintaining good fuel economy and particulate emissions within the 1991 standards. Analysis of results indicates that injection timing and rate control, as embodied in the P-TICS approach, is a key technology for achieving these low emissions with good fuel economy.
Technical Paper

Strategies for Meeting Future Harmonised Emissions Standards if Sport Utility Vehicles with Direct Injection Diesel Engines

2001-05-07
2001-01-1932
Future emissions standards (TIER II, LEV2) require that diesel fuelled vehicles meet the same emissions levels as their gasoline counterparts. In addition, Sport Utility Vehicles (SUVs) must comply to the same norms as passenger cars. However the diesel engine has many desirable attributes for SUV applications and an important role to play in addressing fuel consumption and CO2 emissions issues. In-cylinder reduction of pollutants can no longer be relied upon as the major means to meet future standards. Solutions based solely on emissions control technology are also unlikely to yield positive results. The only viable solution is the combined use of in-cylinder emissions control with advanced catalyst technologies. However, a highly integrated approach is required to gain maximum benefit from the technologies used and enable very low targets to be achieved.
Technical Paper

Real-World Emissions Measurements of a Gasoline Direct Injection Vehicle without and with a Gasoline Particulate Filter

2017-03-28
2017-01-0985
The market share of Gasoline Direct Injection (GDI) vehicles has been increasing, promoted by its positive contribution to the overall fleet fuel economy improvement. It has however been reported that this type of engine is emitting more ultrafine particles than the Euro 6c Particle Number (PN) limit of 6·1011 particles/km that will be introduced in Europe as of September 2017 in parallel with the Real Driving Emission (RDE) procedure. The emissions performance of a Euro 6b GDI passenger car was measured, first in the OEM build without a Gasoline Particulate Filter (GPF) and then as a demonstrator with a coated GPF in the underfloor position. Regulated emissions were measured on the European regulatory test cycles NEDC and WLTC and in real-world conditions with Portable Emissions Measurement Systems (PEMS) according to the published European RDE procedure (Commission Regulation (EU) 2016/427 and 2016/646).
Technical Paper

Comparison of Direct Injection Gasoline Combustion Systems

1998-02-23
980154
The methods of operation of four of the leading combustion system designs for fuel only gasoline direct injection (G-DI) engines have been compared by applying a classical analysis procedure for defining fuel transport. The fuel spray requirements for the different systems are discussed in relation to results obtained from a Phase Doppler Anemometry (PDA) rig for different injectors. The combustion systems have then been considered regarding the functional requirements of future G-DI engines. These include power potential, stratified and homogeneous performance, variable air motion requirements, OEID component function monitoring, packaging and manufacturing issues and calibration effort. The paper concludes that there are at least four main approaches capable of producing acceptable combustion and that the choice of system will depend on packaging, cost and manufacturing constraints.
Technical Paper

The Development of a Method for Evaluating the Effect of Fuel Quality on the Cold Starting of a Range of Diesel Engines

1992-09-01
921748
When developing diesel fuel formulations, it is important to ensure that existing engines in the market place start and continue to run satisfactorily at low temperatures. The objective of this project, carried out jointly by Statoil and Ricardo Consulting Engineers Ltd, was to develop a test technique capable of discriminating between different fuels and to apply the technique to a range of experimental fuels tested in six diesel engines. The engines were selected to represent the technologies available in the current vehicle parc, ranging from indirect injection diesel engines used in passenger cars to highly-rated, direct injection engines found in commercial vehicles. These engines were instrumented to measure crankshaft position and speed, in-cylinder pressure and exhaust emissions. Cold start testing was carried out at -16°C and -24°C in Ricardo's cold chamber and data were recorded during the cold starts by analogue recorders and a high speed digital data logger.
Technical Paper

Understanding the Potential of the Non-Aftercooled Navistar 7.3T CNG Engine

1994-03-01
940549
This paper describes the continued development of the Navistar 7.3 litre V8 CNG engine. The project background, objectives and preliminary results have already been described (1). Development results show that U.S. 1994 emissions standards can be comfortably met without the use of electronic air fuel ratio control or an oxidation catalyst. Transient cycle emissions of 1.7 g/bhph NOx + NMHC have been obtained from de-rated engines to be used in field demonstration vehicles. Electronic control will allow 2.5 g/bhph NOx + NMHC to be achieved without de-rating. Further emissions reduction without aftertreatment will depend on aftercooling, which also offers the potential for an increased rating.
Technical Paper

Development Experience of a Multi-Cylinder CCVS Engine

1995-02-01
950165
A system for stratifying recycled exhaust gas (EGR) to substantially increase dilution tolerance has been applied to a multi-cylinder port injected four-valve gasoline engine. This system, dubbed Combustion Control through Vortex Stratification (CCVS), has shown greatly improved fuel consumption at stoichiometric conditions whilst retaining ULEV compatible engine-out NOx and HC emission levels. A production feasible variable air motion system has also been assessed which enables stratification at part load with no loss of performance or refinement at full load.
Technical Paper

Stratified and Homogeneous Charge Operation for the Direct Injection Gasoline Engine - High Power with Low Fuel Consumption and Emissions

1997-02-24
970543
This paper describes an experimental investigation to explore and optimise the performance, economy and emissions of a direct injection gasoline engine. Building on previous experimental direct injection investigations at Ricardo, a single cylinder engine has been designed to accommodate common rail electronically controlled fuel injection equipment together with appropriate port configuration and combustion chamber geometry. Experimental data is presented on the effects of chamber geometry, charge motion and fuel injection characteristics on octane requirement, lean limit, fuel consumption and exhaust emissions at typical automotive engine operating conditions. The configuration is shown to achieve stable combustion at air/fuel ratios in excess of 50:1 enabling unthrottled operation over a wide operating range. Strategies are demonstrated to control engine out emissions to levels approaching conventional port injected gasoline engines.
Technical Paper

Gasoline Engine Combustion—Turbulence and the Combustion Chamber

1981-02-01
810017
A research programme has been carried out to investigate the effects of operating gasoline engines with different combustion systems. The results showed that at high compression ratios (13:1) compact combustion chambers allowed an increase in compression ratio of between 1 and 2½ numbers for a given fuel quality compared to conventional designs. Fuel economy benefits of about 10% could be achieved by using high ratio compact chambers and lean operation.
Technical Paper

Engine Transmission Matching to Improve Passenger Car Fuel Economy

1982-02-01
820167
A compact passenger car was modified to allow operation with up to six manual gear ratios and up to 35.4 mile/h per 1000 rev/min. Fuel consumption tests were carried out at steady state conditions, over the U.S. Federal urban drive cycle and on the road. Fuel economy improvements of up to 24% were achieved on the road, and up to 25% on the chassis dynamometer over the urban cycle, confirming computer predictions.
Technical Paper

Gasoline Engine Combustion - The High Ratso Compact Chamber

1982-02-01
820166
The use of high ratio compact combustion chambers in gasoline engines has been investigated. The objectives of the research are improved fuel economy within a given set of exhaust emission constraints. The effects of a number of parameters such as swirl, compression ratio and combustion chamber geometry have been investigated, and the conclusions are that for Europe, 13:1 compression ratio is feasible and should yield 10% better fuel economy in passenger cars, while for the USA and Japan, 11:1 compression ratio is preferable, and should yield about 5% better fuel economy.
Technical Paper

Nebula Combustion System for Lean Burn Spark Ignited Gas Engines

1989-02-01
890211
Ricardo have successfully applied their lean burn gasoline engine technology to spark ignited natural gas engines for industrial applications. An open chamber combustion system using the patented ‘Nebula’ chamber, designed as a simple conversion of a swirling direct injection diesel engine, has been tested as a part of the Ricardo internally funded research programme with very promising results. The tests with a 170 × 170 mm single cylinder research engine have shown that the Nebula gas engine provides fast combustion without excessive cyclic variation up to an air:fuel ratio of 26.5:1 or 1.67 excess air ratio. The test results achieved confirm the potential of the Ricardo Nebula combustion chamber as a lean burn combustion system. Many existing emissions standards were met with good fuel consumption, and the stringent West German and Swiss NOx limits were met at 1200 rev/min without penalties in thermal efficiency through excessive ignition retard.
Technical Paper

Optimization of Heavy-Duty Diesel Engine Transient Emissions by Advanced Control of a Variable Geometry Turbocharger

1989-02-01
890395
Ricardo have developed a systematic approach for the design of transient engine control strategies using advanced control techniques. The methodology was initially applied to the design of a testbed speed and torque controller. This enabled complex transient tests to be carried out with equipment normally used for steady-state testing. The same techniques were applied to the design of a controller for a variable geometry turbocharger aimed at vehicle applications. The influence of different control strategies on emissions and fuel economy was evaluated on a heavy-duty diesel engine over a section of the US FTP cycle. Particulate reductions of up to 34% were achieved without increasing NOx.
Technical Paper

An Investigation of Cylinder Pressure as Feedback for Control of Internal Combustion Engines

1989-02-01
890396
The advantages of closed, loop over open loop control systems are generally recognised. However, existing engine management systems implement most control functions in open loop because suitable feedback sensors are not available. Even for so-called closed loop air fuel ratio controllers, shortcomings of the exhaust gas oxygen (EGO) sensor limit the potential effectiveness of closed loop control. A more direct measure of the combustion process, such as cylinder pressure, can yield sufficient information for the closed loop operation of many of the combustion control functions; this paper presents the results of a prediction algorithm which can derive a variety of feedback signals from cylinder pressure. Cylinder pressure, together with several combustion variables, including air-fuel ratio, exhaust gas recirculation rate, and NOx HC, CO and CO2 emissions were measured at various operating points.
Technical Paper

Low Emissions Approaches for Heavy-Duty Gas-Powered Urban Vehicles

1989-09-01
892134
Natural gas is one of the alternative fuels to diesel being considered for low emissions heavy-duty applications. The favoured operating strategies for low emissions SI gas engines are identified as those with high levels of dilution - stoichiometric operation with EGR, and lean-burn. A well-matched exhaust catalyst is needed to produce the lowest emissions levels. Increasing the accuracy of transient air-fuel ratio control is shown to improve the emissions still further. The most favourable combinations of engine operating strategy and control accuracy are identified with respect to fuel economy and first cost. The Co-Nordic Natural Gas Bus Project is an example of an engine development programme aimed at achieving the lowest possible exhaust emissions levels, and as such uses the lowest emissions approach of a stoichiometric engine strategy with EGR and high accuracy control.
Technical Paper

Warm-Up Strategies For a Methanol Reformer Fuel Cell Vehicle

2000-03-06
2000-01-0371
With current technology, a PEM fuel cell powered vehicle requires a plentiful supply of clean hydrogen to achieve good performance. This can be made available via an on-board methanol reformer. Before the reformer reaches operating temperature it is necessary to obtain energy from an alternative source, such as a battery, in order to power the vehicle. This paper introduces a dynamic model of a methanol reformer fuel cell powered vehicle. The vehicle model is driven over the FTP drive cycle, from a cold start, using various warm up strategies. In this way, different strategies are evaluated in terms of performance and fuel efficiency.
Technical Paper

A Premium Heavy Duty Engine Concept for 2005 and Beyond

1999-03-01
1999-01-0831
It is expected that heavy duty engine legislation in Europe will continue to drive down test cycle BSNox emissions to levels of between 2.5 and 3.5 g/kWh by 2005, with a reduction in particulate emissions to between 0.02 and 0.08 g/kWh. It is unlikely that re-optimisation of existing engine combustion systems alone, such as further retardation of the fuel injection timing, will be sufficient to meet the legislated BSNox targets. Other measures, such as cooled EGR or new aftertreatment systems must therefore be considered. Such emissions control strategies may conflict with other market requirements for improved fuel consumption and increased power density. In this paper, research at Ricardo into the configuration of a premium heavy duty truck engine for the European market for model year 2005 and beyond, is described. A review of the market requirements, projected to 2005 was undertaken in order to define the specification of the concept engine.
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