Wallace R. Wade

ADVANCED TECHNIQUES FOR THERMAL AND CATALYTIC DIESEL PARTICULATE TRAP REGENERATION

Advanced techniques for regenerating diesel particulate traps are described. A bypassable trap system minimized regeneration thermal energy requirements. Thermal regeneration systems with burners or electric resistance heaters were evaluated. Regeneration emissions and fuel consumption penalties were measured. Catalytic fuel additives consisting of octoate based compounds of copper and nickel, and copper and cerium provided reductions of up to 410/sup 0/F in trap regeneration temperature. Durability tests confirmed frequent self regeneration with fuel additives.

Fuel economy opportunities with an uncooled Dl diesel engine

Possibilites de realiser des economies de carburant avec un moteur diesel a injection directe non refroidi

THERMAL AND CATALYTIC REGENERATION OF DIESEL PARTICULATE TRAPS

Thermal and catalytic techniques for regenerating particulate traps were assessed. The thermal technique used a burner which heated engine exhaust to the ignition temperature of the particulates to achieve over 90% regeneration effectiveness. HC, CO and particulate emissions resulting from combustion of particulates and burner exhaust were 25 to 50% of the allowable vehicle emissions for one CVS cycle. The fuel consumed by the burner was 9% of the fuel consumed by a vehicle over one CVS cycle. Problems with burner nozzle clogging, ignition reliability, trap durability and control system requirements were identified. In the catalytic technique, diesel fuel containing .5 gm/gal lead and .25 gm/gal copper lowered the ignition temperature of the particulates by 425 deg F so that periodic regeneration occurred. The trap collected nearly all of the lead and copper resulting in limited trap life, and deposits on the engine fuel nozzles tended to increase HC emissions.

CURRENT AND FUTURE LIGHT DUTY DIESEL ENGINES AND THEIR FUELS

Fuel economy improvements have been responsible for the increased interest in diesel engines for light duty vehicles. However, improvements in gasoline engine fuel economy, more stringent emission requirements and reductions in fuel quality pose technical challenges to the diesel engine. Reductions in fuel quality increase emissions, noise and cold starting difficulty. Electronic controls, combustion chamber modifications, and particulate traps, which are not yet feasible, can reduce emissions. Improvements in fuel economy can result from reductions in friction, the use of direct injection and reductions in heat loss to approach adiabatic operation, but with increased costs. Future non-petroleum fuels could differ from diesel fuel and affect combustion performance. Since the cetane number may not predict combustion performance of future fuels, a new concept for evaluating diesel fuels is suggested. A direct injection, ignition assisted engine, if successfully developed, could operate on a variety of fuels with high overall energy utilization efficiency.

Direct injection diesel capabilities for passenger cars

Capabilities of DI diesel engines for passenger cars were evaluated in a research program. Three experimental DI diesel engines, a naturally aspirated 2.4L four cylinder engine and a naturally aspirated and turbocharged 1.3L three cylinder engine, were designed, built and developed. Design parameters and calibrations were determined for optimized power and fuel economy at low emission levels. The effects of cylinder displacement and turbocharging were evaluated. Vehicle tests showed that the DI diesel engine provided an 11 to 13% improvement in fuel economy relative to the IDI diesel engine. The low mileage objectives assumed for the 1985 Federal emission standards were met at vehicle test weights up to 3125 lbs.

A Structural Ceramic Diesel Engine-The Critical Elements

A structural ceramic diesel engine has the potential to provide low heat rejection and significant improvements in fuel economy. Analytical and experimental evaluations were conducted on the critical elements of this engine. The structural ceramic components, which included the cylinder, piston and pin, operated successfully in a single cylinder engine for over 100 hours. The potential for up to 8-11% improvement in indicated specific fuel consumption was projected when corrections for blow-by were applied. The ringless piston with gas squeeze film lubrication avoided the difficulty with liquid lubricants in the high temperature piston/cylinder area. The resulting reduction in friction was projected to provide an additional 15% improvement in brake specific fuel consumption for a multi-cylinder engine at light loads.