Engine efficiency enhancement and operation range extension by argon power cycle using natural gas

Shuguo Shi, Yasutaka Tomomatsu, Bhaskar Chaturvedi, Miguel Sierra Aznar, Jyh Yuan Chen

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Argon power cycle engine has been proved as a promising technology to increase engine efficiency and to reduce engine out emissions. In this research work, experiments were conducted in a port injection single-cylinder engine with air and argon/oxygen as the working fluids under spark ignition, homogeneous charge compression ignition, and spark assisted compression ignition conditions. Natural gas was used as fuel. Experimental results indicate that argon power cycle increases thermal efficiency, extends lean burn limit, suppresses oxides of nitrogen and unburned hydrocarbon emissions, compared to conventional air cycle. The maximum thermal efficiency of argon power cycle reaches 41.5% under low equivalence ratios and high compression ratio conditions. Given a fixed oxygen content, the thermal efficiency increases with decreasing equivalence ratio until the lean burn limit. With the decrease of oxygen content from 21% to 7.5%, the thermal efficiency of argon power cycle first increases and then drops with the peak occurring at ~15%. In practical applications, the engine load of argon power cycle can be controlled by changing equivalence ratio, oxygen content, or both. With argon power cycle, the use of spark assisted compression ignition can further increase the combustion stability, thermal efficiency, and decrease unburned hydrocarbon emission. Combined with an optimal spark timing, the engine cycle's coefficient of variation of the indicated mean effective pressure decreases up to 84% and the thermal efficiency increases up to 2%, compared to homogeneous charge compression ignition.
Original languageEnglish (US)
Pages (from-to)116109
JournalApplied Energy
StatePublished - Nov 2 2020
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-06-14
Acknowledged KAUST grant number(s): OSR-2016-CPF-2909-02
Acknowledgements: The initial research was supported by the California Energy Commission: Energy Innovations Small Grant No. 5804A/14-07G, and later by the King Abdullah University of Science and Technology, Sub-award Agreement Ref. No.OSR-2016-CPF-2909-02. The construction of the experiment was made possible by the donation of fuel injection and piping equipment by Bosch and Parker Hannifin, respectively. The authors would like to acknowledge the help provided by Ms. Yi Zhang from Osaka University on post-processing the emission data while she visited University of California at Berkeley as a visiting student.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

ASJC Scopus subject areas

  • General Energy
  • Civil and Structural Engineering


Dive into the research topics of 'Engine efficiency enhancement and operation range extension by argon power cycle using natural gas'. Together they form a unique fingerprint.

Cite this