Development of 2-Stage Turbocharging Technology on a Medium Speed Diesel Engine

Abstract

This study aims to investigate the potential of a 2-stage turbocharging system to reduce NOx emission. First, 1D cycle simulation model implementing high boost pressure, which imitates 2-stage turbocharging system, was calculated, and it was confirmed that with the combination of early intake valve closing, there is a potential to reduce NOx from conventional single turbocharging engine model without any fuel consumption penalty. Then, the 2-stage turbocharging system was coupled to a medium speed 6-cylinder experimental diesel engine, and test runs were carried out to confirm the potential. Results of the test run show that 2-stage turbocharging system has the potential to reduce NOx as estimated, and as a co-product, BSFC improvement was confirmed when allowing Tier II level NOx emission. Furthermore, engine output increment was possible, without deteriorating BSFC-NOx trade-off relationship. Further development is planned to meet IMO NOx Tier III regulation.