Experimental investigation of sparkplug ion sensor signals in HCCI combustion using sodium, potassium, and cesium acetates as additives

J. H. Mack*, R. H. Butt, S. Saxena, J. Y. Chen, Robert Dibble

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Measuring the ion current with a sparkplug ion sensor in a homogeneous charge compression ignition (HCCI) engine can be used to accurately detect combustion timing. HCCI engines typically operate at lean equivalence ratios. Under these conditions, the ion current becomes increasingly indistinguishable from background noise. This paper investigates various fuel additives for ion signal enhancement at low equivalence ratios and determines side effects of metal acetate addition. The fuel additives added to ethanol were sodium acetate (NaOAc), potassium acetate (KOAc), and cesium acetate (CsOAc). Concentration levels of 100, 200, and 400 mg/L of metal acetate-in-ethanol are investigated over equivalence ratios of 0.11, 0.22, 0.28, and 0.32. The engine operated under naturally aspirated conditions and maintained a constant timing of 2.5o after top-deadcenter (ATDC) at the crank angle degree (CAD) where 50% of the heat release occurs (CA50). CsOAc consistently produced the strongest ion signals, followed by KOAc and NaOAc, which NaOAc had the weakest effect on ion signal. No distinguishable ion signals were measured at an equivalence ratio of 0.11, but significant ion signal improvements occurred at an equivalence ratio of 0.22 using the fuel additives. However, the addition of the metal acetates decreased heat release rates (HRR) and peak cylinder pressures. Although CsOAc produced the largest signal improvements, it also had the largest decrease in HRR and peak cylinder pressure.

Original languageEnglish (US)
Title of host publicationWestern States Section of the Combustion Institute Spring Technical Meeting 2014
PublisherWestern States Section/Combustion Institute
Pages465-480
Number of pages16
ISBN (Electronic)9781632665218
StatePublished - Jan 1 2014
EventWestern States Section of the Combustion Institute Spring Technical Meeting 2014 - Pasadena, United States
Duration: Mar 24 2014Mar 25 2014

Publication series

NameWestern States Section of the Combustion Institute Spring Technical Meeting 2014

Other

OtherWestern States Section of the Combustion Institute Spring Technical Meeting 2014
CountryUnited States
CityPasadena
Period03/24/1403/25/14

Keywords

  • Combustion timing
  • Ethanol
  • Fuel additive
  • HCCI
  • Ion sensing

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physical and Theoretical Chemistry
  • Mechanical Engineering

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