Simulation of System Brake Efficiency in a Double Compression-Expansion Engine-Concept (DCEE) Based on Experimental Combustion Data

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

Abstract

The double compression-expansion engine concepts (DCEE) are split-cycle concepts where the compression, combustion, expansion and gas exchange strokes occur in two or more different cylinders. Previous simulation studies reveal there is a potential to improve brake efficiency with these engine concepts due to improved thermodynamic and mechanical efficiencies. As a continuation of this project this paper studies an alternative layout of the DCEE-concept. The concept studied in this paper has three different cylinders, a compression, a combustion and an expansion cylinder. Overall system indicated and brake efficiency estimations were based on both engine experiments and simulations. The engine experiments were carried out at 10 different operating points and 5 fuelling rates (between 98.2 and 310.4 mg/cycle injection mass) at an engine speed of 1200 rpm. The inlet manifold pressure was varied between 3 and 5 bar. Due to concerns with structural stability the peak cylinder pressure during the engine experiments was limited to 210 bar. Exhaust backpressure was limited to 8 bar due to thermal stress on the exhaust valves. The engine experiments reveal that a gross indicated efficiency (GIE) of 47 % is achieved at most of the operating points. There were cases where GIE was below 45 % due to high heat loss and degraded combustion efficiency.
The data obtained from the engine experiments were then used as input into the full DCEE-engine simulations. System brake efficiency was determined by estimating friction loss in the simulations. These simulations and friction estimations suggests a system brake efficiency of 41.8 % at the lowest fuelling rate (98.2 mg/cycle) is achieved. Increasing engine load improves efficiency due to lower relative intercooling loss and improved mechanical efficiency. A peak system brake efficiency of 52.8 % is achieved at a very high injection mass (275.6 mg/cycle) and 5 bar Pinlet setting. A further increase in injection mass to 310.4 mg/cycle results in a high increase in heat loss which causes system brake efficiency to decrease to 49.9 %.

Details

Authors
Organisations
External organisations
  • Volvo Group Trucks Technology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering
  • Vehicle Engineering
Original languageEnglish
Title of host publication International Powertrains, Fuels & Lubricants Meeting
PublisherSociety of Automotive Engineers
Publication statusPublished - 2019 Jan 15
Publication categoryResearch
Peer-reviewedYes
EventSAE International Powertrains, Fuels & Lubricants Meeting - Marriott Hotel Riverwalk, San Antonio, United States
Duration: 2019 Jan 222019 Jan 24

Publication series

NameSAE Tecnical Papers
ISSN (Print)0148-7191

Conference

ConferenceSAE International Powertrains, Fuels & Lubricants Meeting
CountryUnited States
CitySan Antonio
Period2019/01/222019/01/24

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Per Tunestål, Nhut Lam, Kenan Muric & Bengt Johansson

Swedish Energy Agency

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Project: ResearchCollaboration with industry

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