STUDY OF HEAT RELEASE SHAPING VIA DUAL-CHAMBER PISTON BOWL DESIGN TO IMPROVE ETHANOL-DIESEL COMBUSTION PERFORMANCE

Paper #:
  • 2017-01-0762

Published:
  • 2017-03-28
Abstract:
This work targets to implement heat release shaping control for improving the ethanol-diesel combustion performance by utilizing a dual-chamber piston bowl design. Unlike the conventional diesel diffusion combustion, new combustion strategies (e.g. dual-fuel combustion) tend to achieve clean combustion by burning a (partially) premixed cylinder charge. However, the rapid heat release from premixed combustion can result in excessive combustion noise and/or high pressure rise rates, which is one of the major barriers preventing these advanced combustion strategies to be fully applied over the entire engine operation map. In order to avoid the fast heat release, an innovative piston bowl design, which physically divides the combustion chamber into a central zone and a peripheral zone near the top dead center, is employed to assist the control of the ethanol-diesel combustion process via heat release shaping. The spatial combustion zone partition divides the premixed ethanol-air mixture into two portions, and the premixed combustion event (timing and extent) of each portion can be controlled by the temporal diesel injection scheduling. As a result, the heat release profile of ethanol-diesel combustion can be properly shaped to reduce combustion noise and improve the engine performance. The investigation is carried out through theoretical simulation study and empirical engine tests. Parametric simulation is first performed to evaluate the effects of heat release shaping on combustion noise and engine efficiency and to provide boundary conditions for subsequent engine tests. The engine tests are conducted on single cylinder research engines, namely a high compression ratio (18.2:1) engine with a conventional piston bowl and a low compression ratio (14:1) engine with the dual-chamber piston bowl. These research engines provide independent control of intake boost and exhaust gas recirculation along with flexible fuel injection control. The engine performance is examined through emission measurements and efficiency analyses, and combustion characteristics are investigated focusing on the correlation between combustion noise and heat release shaping. The comparison between these two engines manifests the advantages of the dual-chamber bowl design for heat release shaping control. By controlling the diesel pilot injections (number, quantity and timing), the heat release profiles representing the combustion events in the central zone and peripheral zone can be adjusted towards the desired heat release shaping as suggested by the simulation results. As indicated by the test results, the dual-chamber piston bowl along with an injection strategy using an early diesel pilot is for the peripheral zone and a near-TDC diesel pilot for the central zone shows a great potential of achieving clean, efficient, and smooth ethanol-diesel combustion.
Access
Now
SAE MOBILUS Subscriber? You may already have access.
Buy
Attention: This item is not yet published. Pre-Order to be notified, via email, when it becomes available.
Select
Price
List
Download
$22.00
Mail
$22.00
Members save up to 36% off list price.
Share
HTML for Linking to Page
Page URL

Related Items

Technical Paper / Journal Article
2003-01-18
Article
2016-03-01
Technical Paper / Journal Article
2004-01-16
Article
2016-03-04
Technical Paper / Journal Article
2010-10-06