Influence of the compression ratio on the performance and emissions of a mini HCCI engine fuelled with diethyl ether

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding

Abstract

Power supply systems play a very important role in applications of everyday life. Mainly, for low power generation, there are two ways of producing energy: electrochemical batteries and small engines. In the last few years many improvements have been carried out in order to obtain lighter batteries with longer duration but unfortunately the energy density of 1 MJ/kg seems to be an asymptotic value. If the energy source is an organic fuel with an energy density of around 29 MJ/kg and a minimum overall efficiency of only 3.5%, this device can surpass the batteries. Nowadays the most efficient combustion process is HCCI combustion which is able to combine high energy conversion efficiency and low emission levels with a very low fuel consumption.

In this paper, an investigation has been carried out concerning the effects of the compression ratio on the performance and emissions of a mini, Vd me 4.11 [cmu3], HCCI engine fueled with diethyl ether. Because of its high reactivity, autoignition of the mixture was achieved only using compression energy. The compression ratio was changed by altering the squish distance: 0.25, 0.50, 0.75, 1.00 and 1.25 [mm]. For each compression ratio, three sets of measurements were performed: 3000, 7000 and 12000 [rpm]. The study showed that diethyl ether was only slightly affected by quenching problems when the squish distance was 0.25 and 0.50 [mm] at 7000 [rpm]. It was also demonstrated that the performance improved when decreasing the compression ratio to an optimum point and subsequently dropped to zero when the highest spacer, 1.25 [mm], was used. Due to a very low combustion and thermodynamic efficiencies, the specific emissions of CO and HC were one order of magnitude higher than for a normal car/truck engine, whereas NOx emissions were comparable to those of a conventional diesel engine. Finally, the study rendered it possible to understand how much an HCCI engine fueled with diethyl ether could be scaled down since it was shown that this fuel was not very sensitive to quenching, with a squish distance of 0.25 [mm].

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Mechanical Engineering

Keywords

  • power supply, HCCI, engine, mini engine, combustion
Original languageEnglish
Title of host publicationSAE Technical Paper Series
PublisherSociety of Automotive Engineers
Publication statusPublished - 2007
Publication categoryResearch
Peer-reviewedYes
EventSAE Powertrain & Fluid Systems Conference and Exhibition, 2007 - Chicago, United States
Duration: 2007 Oct 292007 Oct 31

Publication series

Name
ISSN (Print)0148-7191

Conference

ConferenceSAE Powertrain & Fluid Systems Conference and Exhibition, 2007
CountryUnited States
CityChicago
Period2007/10/292007/10/31