Philip Gerald Blakeman

Optimising the Low Temperature Performance and Regeneration Efficiency of the Continuously Regenerating Diesel Particulate Filter (CR-DPF) System

An electrooptical scanning device which can detect the relative position of register mark applied to a moving web, either serially on a single track or in two parallel, side-by-side tracks which extend in the direction of movement of the web. Light from a light source positioned some distance above the web is split into three light beams and the light beams are reflected downwardly towards the web. Lenses are positioned to receive and direct the light beam at an oblique angle onto the marks on the track or tracks. The lenses are aligned with the tracks and the light beam passing through a given lens is directed to the opposite track to illuminate three positions, two on the first track and one position on the second track. Light impinging on the web at these positions is scattered. Vertically upwardly scattered light is captured by the lens overlying the particular illuminated position and hence directed via suitable optics to photo-detectors which generate output signals that can be used to determine the relative locations of the marks to thereby detect any misalignments of the web.

The Use of NO x Adsorber Catalysts on Diesel Engines

NOx adsorber catalysts (NACs) can be applied in lean-burn gasoline and diesel engines to reduce NOx emissions. Typically NACs are formulated using platinum as an oxidation catalyst, barium as a storage component and rhodium for NOx reduction. There has been intense research to optimise these catalysts for use on diesel engines aimed at increasing their efficiency, durability, sulfur tolerance and operating temperature window. This paper describes these developments and outlines the current level of knowledge of NOx adsorber catalyst systems using results from small-scale laboratory tests as well as engine-bench work.

The Development and Performance of the Compact SCR-Trap System: A 4-Way Diesel Emission Control System

The tightening of Heavy Duty Diesel (HDD) emissions legislation throughout the world is leading to the development of emission control devices to enable HDD engines to meet the new standards. NOx and Particulate Matter (PM) are the key pollutants which these emission control systems need to address. Diesel Particulate Filters (DPFs) are already in use in significant numbers to control PM emissions from HDD vehicles, and Selective Catalytic Reduction (SCR) is a very promising technology to control NOx emissions. This paper describes the development and performance of the Compact SCR-Trap system - a pollution control device comprising a DPF-based system (the Continuously Regenerating Trap system) upstream of an SCR system. The system has been designed to be as easy to package as possible, by minimising the total volume of the system and by incorporating the SCR catalysts on annular substrates placed around the outside of the DPF-based system. This novel design gives rise to an easy-to-package emission control device capable of providing very high conversions of all four major pollutants, NOx, PM, CO and HC. The design details are discussed, and the performance of the system over both steady state and transient cycles is presented. NOx conversions of up to 92% have been demonstrated, and the systems emissions of all four pollutants are well inside the Euro V, and probably also the US 2007 limits (subject to verification of PM).

The Development and In-Field Demonstration of Highly Durable SCR Catalyst Systems

Selective Catalytic Reduction (SCR) systems will be widely used to meet the Heavy Duty Diesel (HDD) Euro IV emissions legislation. Reports on a number of demonstrations of such systems have already been published, but the long-term durability of such systems is still to be proven. The potential catalyst deactivation induced by oil-derived species and thermal processes have, up to now, received very little attention, despite the fact that these HDD emission control systems will need to be durable for distances of the order of 500,000 km or more. This paper describes the development and performance of a new family of SCR catalyst with very high thermal durability and poison resistance. The thermal durability of the catalyst was initially demonstrated within long-term, high temperature engine bench ageing studies. Following the demonstration of the excellent thermal durability of the new catalyst, its resistance to poisoning by oil-derived species was studied using a mixed driving, engine bench ageing cycle, with substantial periods of high temperature exposure. Very little catalyst deactivation was observed, even after treatments corresponding to over 1 million km of real-world driving (based on oil consumption). The catalyst has been incorporated into an SCRT® system, a four-way emission control system comprising a CRT® particulate filter system and an SCR system. This system has accumulated over 125,000 km of on-road driving in a mid-west to west coast long-haul US application. The performance of the system has been checked periodically. Average on-road NOx conversions of up to 82% were observed, when using an injection strategy in which the ammonia-to-NOx ratio was only 0.85 (ie giving a maximum possible NOx conversion of 85%). These high conversions were averaged over an on-road drive cycle which covered 850 km. During the course of the 125,000 km accumulated on the road, no deterioration in the NOx conversion of the system was observed, attesting to the excellent field durability of the SCR catalysts within this SCRT system.

Performance of NOx Adsorber Emissions Control Systems for Diesel Engines

Increasingly stringent Diesel vehicle emissions legislation around the world means that advanced aftertreatment systems may be required to achieve the required nitrogen oxide (NOx) emissions rather than through engine control measures alone. As in lean-burn gasoline applications, NOx adsorber systems offer great potential for high level NOx conversion in Diesel exhaust, and their use on Diesel engines is an area of intense interest for possible use in light-duty and heavy-duty applications. This paper is concerned with the performance of advanced NOx adsorber catalysts developed specifically for the requirements of light-duty Diesel vehicles. Laboratory and engine bench data are discussed that demonstrate NOx conversions in excess of 90% over a wide temperature window can be achieved. The durability characteristics of these catalysts are also reported. The ability to tune the NOx adsorber formulation to an operating window for a specific application and/or position in the exhaust is important for the optimisation of a full emissions control system. This paper presents operating temperature windows of some optimised NOx adsorber catalysts for maximisation of the operating window at low and high temperatures.