A path towards high efficiency using Argon in an HCCI engine

  • Abdulrahman Mohammed

Student thesis: Master's Thesis


Argon replacing nitrogen has been examined as a new engine cycle to reach high efficiency. Experiments were carried out under Homogeneous Charge Compression Ignition (HCCI) conditions using a single cylinder variable compression ratio Cooperative Fuel Research (CFR) engine. Isooctane has been used as the fuel for this study. All the parameters were kept fixed but the compression ratio to make the combustion phasing constant. Typical engine outputs and emissions were compared to conventional cycles with both air and synthetic air. It has been found that the compression ratio of the engine must be significantly reduced while using argon due to its higher specific heat ratio. The resulting in-cylinder pressure was lower but combustion remains aggressive. However, greater in-cylinder temperatures were reached. To an end, argon allows gains in fuel efficiency, in unburned hydrocarbon and carbon monoxide, as well as in indicated efficiency. A higher nitrogen oxide concentration while replacing nitrogen by argon was observed but the origin remains to be identified. The concept should therefore be able to reach zero-NOx emissions as no nitrogen should be present.
Date of AwardNov 2018
Original languageEnglish (US)
Awarding Institution
  • Physical Sciences and Engineering
SupervisorBengt Johansson (Supervisor)


  • Engines
  • high efficiency
  • Argon
  • HCCI
  • CFR
  • Combustion

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