Investigating Effects of Direct Injection During NVO on HCCI Combustion
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Investigating Effects of Direct Injection During NVO on HCCI Combustion. Effects of PreDI %. Students: John Waldman, Dennis Nitz Advisor:Prof. David E. Foster Visiting Researchers: Takeru Ibara, Minoru Iida Funding by:Yamaha Motor Company. Definitions.

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Investigating Effects of Direct Injection During NVO on HCCI Combustion

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Investigating effects of direct injection during nvo on hcci combustion

Investigating Effects of Direct Injection During NVO on HCCI Combustion

Effects of PreDI %

Students: John Waldman, Dennis Nitz

Advisor:Prof. David E. Foster

Visiting Researchers: Takeru Ibara, Minoru Iida

Funding by:Yamaha Motor Company

Definitions

  • Negative Valve Overlap (NVO) – time during end of exhaust stroke and beginning of intake stroke when both intake and exhaust valves are closed

  • PreDI – Early Direct fuel injection during negative valve overlap

  • DI – Secondary Direct fuel injection during intake stroke

  • PI – Port fuel injection during intake stroke

Single Cylinder Yamaha Research Engine

Objectives

Effects of PreDI% on HCCI combustion. Note: the combustion timing is advanced with higher percentages of PreDI. Also NOx emissions are more sensitive to changes in PreDI % at leaner AFR.

  • Outline HCCI operating regime

  • Study effects on HCCI combustion from varying:

    • PreDI percent of total fuel flow

    • PreDI timing and duration

    • PI and DI durations

Effects of PreDI Timing

PI Duration (usec)

PI Duration (usec)

Laboratory Schematic

eTDC

eTDC

EVC

EVC

Baseline Operating Range

Effects of PreDI timing with different amounts of PI fuel. Note: the timing is retarded as PreDI timing is retarded. Also, THC emissions reach a minimum value around 430 CAD bfTDC.

Summary

  • Pre-DI timing can control:

    1. Timing of HCCI combustion

    2. Emissions produced from HCCI combustion

  • Varying the pre-DI % of total fuel injection can also be used to

    influence the timing of HCCI combustion and emissions

    output.

  • Different trends in combustion efficiency were found using

    Port Injection vs. Direct Injection.

Valve Timings and Details

Operating range obtained with current valve timings for both Port Injection and Direct Injection with PreDI. This map was obtained with fixed valve timing, fixed injection timing, fixed PreDI duration and the load varied by reducing the PI or DI duration.

Combustion Efficiency

Future Work

  • Improving HCCI combustion by:

    • Varying PreDI timing with shorter injection durations

    • Increasing coolant temperature to help expand lower load limit

    • Using different fuels with PreDI injection

    • Varying PreDI timings and durations with lower amounts of trapped exhaust gas residuals

Port Injection vs. Direct injection Combustion Efficiency. Note the different trends from PI to DI.


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