Variable compression ratio in diesel engines

Diezemann, Matthias; Schramm, Christian; Brauer, Maximilian; Severin, Cecilia

doi:10.1007/s38313-015-0024-8

Cited by 2 publications

(1 citation statement)

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“…Therefore, no such high intake boosting pressure up to 0.6 MPa is expected with the IEGR + LP/EGR configuration. In addition, intake boost pressure of up to 0.5 MPa maximum was proposed recently in both simulation and experiment of a VCR engine, 16,17 revealing the trend of downsizing concept and the necessity to increase the specific power output per cylinder volume. Increasing the intake pressure up to 0.5 MPa does not seem to be of concern with future turbocharger technologies, insofar as the abovementioned IEGR + LP-EGR concept exhibits potential for engine performance and emissions.…”

Section: Introductionmentioning

confidence: 99%

Emission reduction through internal and low-pressure loop exhaust gas recirculation configuration with negative valve overlap and late intake valve closing strategy in a compression ignition engine

Kim

Bae

2017

International Journal of Engine Research

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An investigation was carried out to examine the feasibility of replacing the conventional high-pressure loop/low-pressure loop exhaust gas recirculation with a combination of internal and low-pressure loop exhaust gas recirculation. The main objective of this alternative exhaust gas recirculation path configuration is to extend the limits of the late intake valve closing strategy, without the concern of backpressure caused by the high-pressure loop exhaust gas recirculation. The late intake valve closing strategy improved the conventional trade-off relation between nitrogen oxides and smoke emissions. The gross indicated mean effective pressure was maintained at a similar level, as long as the intake boosting pressure kept changing with respect to the intake valve closing timing. Applying the high-pressure loop exhaust gas recirculation in the boosted conditions yielded concern of the exhaust backpressure increase. The presence of high-pressure loop exhaust gas recirculation limited further intake valve closing retardation when the negative effect of increased pumping work cancelled out the positive effect of improving the emissions’ trade-off. Replacing high-pressure loop exhaust gas recirculation with internal exhaust gas recirculation reduced the burden of such exhaust backpressure and the pumping loss. However, a simple feasibility analysis indicated that a high-efficiency turbocharger was required to make the pumping work close to zero. The internal exhaust gas recirculation strategy was able to control the nitrogen oxides emissions at a low level with much lower O2 concentration, even though the initial in-cylinder temperature was high due to hot residual gas. Retardation of intake valve closing timing and intake boosting contributed to increasing the charge density; therefore, the smoke emission reduced due to the higher air–fuel ratio value exceeding 25. The combination of internal and low pressure loop loop exhaust gas recirculation with late intake valve closing strategy exhibited an improvement on the trade-off relation between nitrogen oxides and smoke emissions, while maintaining the gross indicated mean effective pressure at a comparable level with that of the high-pressure loop exhaust gas recirculation configuration.

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Section: Introductionmentioning

confidence: 99%