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This paper describes an experimental comparison of loop and cross scavenged single-cylinder research engines. The cross scavenged engines have employed the QUB type deflector piston. The initial results show that the QUB cross scavenged engine exhibited inferior performance characteristics. Utilizing the QUB single cycle test rig, a study of the QUB cross scavenging system has shown that the bore-to-stroke ratio significantly influences the scavenging behaviour; reduction of the bore-to-stroke ratio from over-square values gave improved characteristics. On the basis of this finding, a new cross scavenged cylinder barrel was designed. In a subsequent series of dynamometer tests, improvements in power, fuel economy and emission characteristics were recorded for the new cylinder. These improved results approximate closely to those recorded for the loop scavenged engine and are considerably superior to those of the original cross scavenged cylinder.

Catalyst aging is presently one of the most important aspects in aftertreatment development, with legislation stating that these systems must be able to meet the relevant emissions legislation up to a specified mileage on the vehicle, typically 150,000 miles. The current industry approach for controlling aging cycles is based solely on the detailed specification of lambda (air-fuel mixture concentration ratio), flow rate and temperature without any limitations on gas mixture. This is purely based upon the experience of engine-based aging and does not take into account any variation due to different engine operation. Although accurate for comparative testing on the same engine/engine type, inconsistencies can be observed across different aging methods, engine types and engine operators largely driven by the capability of the technology used.

Understanding the behavior of automotive catalysts formulations under the wide range of conditions characteristic of automotive applications is key to the design of present and future emissions control systems. Platinum-based oxidation catalysts have been in use for some time to treat the exhaust of diesel-powered vehicles and have, as part of an emissions control package, successfully enabled compliance with emissions legislation. However, progressively stringent legislated limits, coupled with the need to reduce vehicle manufacturing costs, is incessantly demanding the development of new and improved catalyst formulations for the removal of pollutants in the diesel exhaust. With the introduction of low sulfur diesel fuel, and the advantageous decline in Palladium prices with respect to Platinum, bimetallic Pt:Pd-based catalysts have found an application in diesel after treatment.

With emission legislation becoming ever more stringent, automotive companies are forced to invest heavily into solutions to meet the targets set. To date the most effective way of treating emissions is through the use of catalytic converters. Current testing methods of catalytic converters whether being tested on a vehicle or in a lab reactor can be expensive and offer little information about what is occurring within the catalyst. It is for this reason and the increased price of precious metal that kinetic modeling has become a popular alternative to experimental testing. Many kinetic models and kinetic parameters have appeared in literature in recent years, a comparison of these kinetic parameters for the global reaction of CO oxidation is presented.

A mathematical model has been developed which predicts the tailpipe exhaust emissions of two-stroke cycle engines utilising an oxidising catalytic converter. This model is currently one-dimensional and has been developed as an aid to the design of engine/exhaust systems. The experimental rig employed has a two-fold function, its primary task was to aid in the validation of the model. Secondary to this it was used to simulate the gaseous properties of the exhaust gas at various positions in the exhaust system. The validation exercise is currently proceeding utilising metallic substrate technology with preliminary results indicating that the model is showing good correlation to measured values.

Previously, an initial investigation examined the effect of the catalytic substrate on the gas dynamics of the blowdown pulse on the QUB single shot rig. This initial investigation measured the resulting waves from the catalytic converter in the exhaust pipe. In this early study the substrate was at ambient temperature but it is recognised that after light-off higher reaction temperatures will result from the exothermic nature of exhaust gas oxidation and reduction. Therefore substantially different results will occur. This paper details a series of experiments which investigate the influence of an operating catalyst on the unsteady gas dynamics in an exhaust system using the QUB single shot rig. In addition to measuring the effect of temperature on the gas dynamics previous work is reviewed with emphasis now on specifically measuring the features present rather than having to decipher superimposed pressure traces.

The after-treatment of exhaust gas using 3-way catalytic converters is now normal practice in automotive applications. For other applications, such as outboards, motorcycles and utility engines, new legislation is now in place in both Europe and North America. Further reduction of the permitted emission levels require the use of catalysts for two-stroke engine applications. However, current automotive catalyst systems are not suitable for durable operation in most two-stroke engines and new analytical tools are required to aid the development engineers in the implementation of revised designs and operating strategies. This paper reviews the range of modeling techniques which have been developed for automotive uses and presents new and modified models suitable for two-stroke engines. This requires particular emphasis to be placed on the oxidation reactions that predominate in the two-stroke engine exhaust.

An increase in global oil consumption, coupled with a peak in oil production, has seen the price of fuel escalate in recent years, and consequently the transport sector must take measures to reduce fuel consumption in vehicles. Similarly, ever-tightening emissions legislation is forcing automotive manufacturers to invest in technology to reduce toxic emissions. In response to these concerns, this project aims to address one of the fundamental issues with the Internal Combustion Engine - approximately one third of the fuel energy supplied to the engine is lost as heat through the exhaust system. The specific aim of this project is to reduce the fuel consumption of a diesel-electric hybrid bus by recovering some of this waste heat and converting it to useful power. This report details how turbocompounding can be applied to the engine, via the inclusion of a turbogenerator, and assesses its waste heat recovery performance.

The results of this paper will show the reader how to quantify a minimum light-off temperature to meet the required emissions standards with the use of a 3-way catalytic converter. The method can be applied to both motorcycle and larger automotive catalysts to help meet their respective emissions standards (Euro 5/Euro 7). The ability to predict a light-off temperature for any catalyst at the beginning of the project saves both time and resource. With an emphasis on how the shape of the light-off curve affects the cumulative tailpipe emissions and how shape of the light-off curves change with the ageing process. Changes in the light-off curves will be reviewed to understand how the chemical reactions and pore diffusion mechanisms within the catalyst deplete to negatively affect performance over its life time.

With emission legislations becoming ever more stringent, there is an increased pressure on after-treatment systems and more specifically three-way catalysts. With recent developments in emission legislations, there is a requirement for more complex after-treatment systems and understanding of the aging process. Whilst the body of understanding on catalyst deactivation and, in particular, catalyst aging is growing, there are still significant gaps in understanding, particularly how real world variations in temperature, flow rate and gas concentrations affect catalyst behavior. Under normal driving conditions, the catalyst can experience varying oxygen concentrations, such as under heavy acceleration or cruising down a hill will show a variation in oxygen from the engine emissions. The effect that varying oxygen concentrations has on the rate of aging is not fully understood and hence the total deactivation and conversion efficiencies are not known throughout the catalyst lifetime.