Tech Briefs
Automotive emission-reduction product

The device generates plasma, changing the chemical properties of exhaust gases and enhancing the catalytic converter's reduction of pollutants that exit the tailpipe. The CDD fits into the exhaust pipe of an automobile, ahead of the catalytic converter.

Major emissions reductions have been made by the automotive industry with the introduction of the catalytic converter and by improvements to engine design. However, to meet increasingly stringent governmental standards, additional technological advancements will be needed.

Catalytic converters are used in automotive exhaust systems to reduce harmful by-products in a vehicle's exhaust, particularly hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The converter uses precious metals as catalysts to partially complete the combustion process in the exhaust system, converting the by-products into less harmful constituents: nitrogen, carbon dioxide, and water. However, catalytic converters are susceptible to contamination, mostly from sulfur in gasoline and sulfur or phosphorus in engine oil, which delay light-off and reduces their efficiency.

A catalyst must be hot to work effectively. A major fraction of the pollutants that exit a tailpipe are created during the first two minutes after an automobile is started, while the catalytic converter is cold. Therefore, reducing the time period before a catalyst lights-off (or reaches an effective operating temperature) significantly reduces emissions. The Corona Discharge Device (CDD) from Litex is said to make the catalyst more active at lower temperatures, allowing the converter to begin operating effectively more quickly.

The CDD is based on technology initiated by Lockheed Martin Corp. The device is inserted upstream of the vehicle's catalytic converter, generating a non-thermal plasma in the exhaust stream of a gasoline-powered car or light truck. This alters the chemical composition of the exhaust, reducing CO emissions by more that 80%, and both HC and NOx emissions by more than 50%, depending upon the sulfur content of the fuel. Since the CDD's "self-cleaning" environment reduces the amount of toxins that enter the catalytic converter, the converter's life is prolonged. The company says that the CDD's capabilities for improving catalytic converter efficiency and reducing potential sulfur poisoning eliminates the need to produce "over-sized" catalytic converters to meet EPA regulations, thus reducing the amount of precious metals required in the converters. The CDD is a low-power device that operates at approximately 25 W, less that the amount of power required to illuminate a car's brake light.

The CDD has been tested on V-6 and V-8 automobile engines running under loads that simulated a wide range of driving conditions. Fuels with varying sulfur content have been tested. The company claims that the testing results also indicate that catalytic converters that have been poisoned during thousand's of miles of driving with high-sulfur gasoline can be significantly regenerated after running with a CDD in the exhaust stream.