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Technical Paper

Oxidation Catalyst Systems for Emission Control of LPG-Powered Forklift Trucks

An oxidation catalyst was installed on an industrial LPG-powered forklift truck. For high conversion efficiency in an oxidation system on a rich burning engine a secondary air supply to the catalyst is necessary. Two simple and cost-effective ways of secondary air supply were tested: an air valve and a venturi type injector. The amount of secondary air supplied by both devices was measured under a variety of conditions - different engine speed, load and exhaust system pressure. Carbon monoxide emissions and the catalyst performance were measured and evaluated in terms of the secondary air flow. Advantages and drawbacks of the air valve and venturi injector systems are discussed and compared.
Technical Paper

On-Vehicle Exhaust Gas Cooling in a Diesel Emissions Control System

A diesel emissions control system built and tested on an industrial forklift truck is described. The system utilizes a pleated media type diesel soot filter. The temperature limit of the filter material is well below the temperature of the exhaust gas. Therefore, cooling of the exhaust gas is necessary. A finned-tube heat exchanger is included in the system to cool the exhaust gas to the required level. The performance of the heat exchanger was investigated. The focus was on the fouling of heat transfer surface by soot and the corresponding decrease of the heat transfer rate. The fouling factor was found. Also, a design practice for finned-tube heat exchangers is presented and its applicability to small size mobile equipment is discussed.
Technical Paper

Evaluation of a Catalyzed Ceramic Diesel Particulate Filter and Catalytic Converter on an Underground Mine Vehicle

The U.S. Bureau of Mines (USBM) and Diesel Controls Limited are evaluating a new diesel emission control system on an underground mine vehicle. The system is a catalyzed ceramic wall-flow diesel particulate filter (CDPF) combined with an oxidation catalytic converter (OCC). It is the first installation in the U.S. of a CDPF on a mining vehicle with a turbocharged engine at a high altitude mine, and the first installation of both a CDPF and an OCC on a mine vehicle. This paper describes the design and installation of the system on the load-haul-dump (LHD) vehicle. The results of screening tests conducted by the USBM are also given. The screening tests were conducted to determine if the device's particulate collection efficiency, regeneration temperature, and effect on gaseous hydrocarbon (HC) and carbon monoxide (CO) emissions changed over the period at was being used. The system was removed from the LHD and evaluated in the laboratory after operating for 308 and 1200 hours.
Technical Paper

Diesel Particulate Filter with a Disposable Pleated Media Paper Element

Experimental work was undertaken to examine the suitability of regular pleated intake-air filter elements for filtration of diesel particulate matter (DPM). The experiments were carried out using a small diesel powered generator set. The exhaust gas was cooled in a heat exchanger. The major investigated issues were the behaviour of the filter media at different temperatures and their filtration efficiency. The investigated, cellulose-based media have a relatively low temperature limit and can be exposed only to cooled exhaust gas. Therefore, the potential areas of application of that technology are vehicles with exhaust gas cooling systems, e.g. mining permissible vehicles. In many other confined space applications, however, where the DPM emissions become critical, the exhaust gas may be purposely cooled to allow for the application of the cellulose filters.

Diesel Emissions and Their Control

This book will assist readers in meeting today's tough challenges of improving diesel engine emissions, diesel efficiency, and public perception of the diesel engine. It can be used as an introductory text, while at the same time providing practical information that will be useful for experienced readers. This comprehensive book is well illustrated with more than 560 figures and 80 tables. Each main section is broken down into chapters that offer more specific and extensive information on current issues, as well as answers to technical questions.