Empirical and Theoretical Investigations of Active-flow Control on Diesel Engine After-treatment

Empirical and theoretical studies are made between active-flow control and passive-flow control schemes in investigating the influences of gas flow, heat transfer, chemical reaction, oxygen concentration, and substrate properties. The exhaust active-flow control includes the parallel alternating flow, partial restricting flow, periodic flow reversal, and extended flow stagnation that are found to be especially effective to treat engine exhausts that are difficult to cope with conventional passive-flow converters [1, 2]. The tests are set up on a single cylinder Yanmar engine. Theoretical studies are performed with the one-dimensional transient modeling techniques to analyze the thermal behavior of the diesel after-treatment systems when active flow control schemes are applied. The combined use of active flow control schemes are identified to be capable of shifting the exhaust gas temperature, flow-rate, and oxygen concentration to more favorable windows for the filtration, conversion, and regeneration processes. The theoretical analysis indicates that the active-flow control schemes have fundamental advantages in optimizing the converter thermal management that includes the supplemental heating, thermal retention, thermal recuperation, and overheating protection.