SBIR-STTR Award

New Federal standards that come into effect in 1988 will require heavy duty diesel exhaust particulate emission reductions of approximately 60%. It has been shown that approximately 75% of diesel particles are changed during combustion and could be collected on the surfaces of an electrostatic agglomerator (ESA). These particles would grow on the surfaces by agglomeration and be reentrained into the gas flow. The agglomerated particles can be collected with inertial collection devices such as cyclones.Taking advantage of this combustion charging of the particles in the operation of a "no corona" ESA would entail essentially no parasitic power demands. This is in contrast to conventional electrostatic precipitators with corona charging sections where electrical power to supply the corona current can be substantial. The focus of this proposal is to characterize the operation of a prototype ESA and to quantify the increase in particle size that is accomplished with the device.

The proposed Federal Standards for diesel exhaust particle emissions in 1991 and 1994 will require a 60% and 83% reduction from the current (1988) standards. It has been shown that approximately 75% of diesel particulates are charged during combustion and could be collected on the surface of in electrostatic agglomeration,, itor with minimal power consumption. During Phase I of the EPA SBIR program, HMI, Inc. successfully demonstrated the electrostatic agglomeration of submicron particles contained in diesel exhaust using the particle's natural charge. The mass mean diameter of the submicron particles was increased from about 0.2 um to about 2.0 um.The focus of this Phase II proposal is to demonstrate the performance of an inertial separator to remove the agglomerated particles from the exhaust stream and to destroy the agglomerate by burning either within the engine or externally. The advantages of this approach for diesel particle control are that the natural occurring particle charge enables the submicron particles to be removed, agglomerated, and subsequently reburned separate from the agglomeration/separation system with a low pressure drop in the exhaust gas stream and at minimal parasitic power consumption. An innovative particle collection system has been developed for diesel exhaust emissions which utilize the natural charge on the submicron particles. The submicron particles are electrostatically removed from the diesel exhaust stream. The particles collect and agglomerate on the surfaces of the electrostatic device. Subsequently, the agglomerated particles are reintrained in the exhaust flow and removed using robust inertial collection devices. Ultimately, the agglomerate is destroyed by reburning.The electrostatic agglomerator system (ESA) will have universal application for all trucks and buses operating in the United States. The ESA particle collection system will allow the 1991 and 1994 diesel emission regulations to be met using a rugged and economical particle collection system.