Improvement in fuel economy is examined and compared for a broad spectrum of truck engines and waste heat utilization concepts. Diesel, spark ignition, gas turbine, and Stirling engines are considered, with principal emphasis on the turbocharged, four-stroke diesel. Because of increased exhaust energy and a large potential for improved performance, the still-to-be-developed adiabatic diesel is also examined. Waste heat utilization concepts considered include preheating, regeneration, turbocharging, turbocompounding, and Rankine engine compounding. Predictions are based on fuel/air cycle analyses, computer simulation, and engine test data, with all options compared on the basis of maximum theoretical improvement. The diesel and adiabatic diesel are also evaluated in terms of maximum expected improvement and expected improvement over a driving cycle. The indication is that diesels should be turbocharged and aftercooled to the maximum possible level. Based on current design practices, up to 6% fuel economy improvements might be possible. Rankine engine compounding can provide about three times as much improvement as turbocompounding, but will cost three times as much. By turbocharging, turbocompounding, and Rankine engine compounding, driving cycle performance could be increased by up to 20% for a diesel and up to 40% for an adiabatic diesel. Rankine engine compounding can provide significant fuel economy improvement for gas turbine and spark ignition engines and regeneration could significantly enhance the performance of the latter. Because of the low heat content of its exhaust, the Stirling engine has only a small potential for further waste heat recovery.

  • Availability:
  • Supplemental Notes:
    • Presented at SAE West Coast Meeting, San Diego, 7-10 August 1978.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • LEISING, C J
    • PUROHIT, G P
    • DeGrey, S P
    • Finegold, J G
  • Publication Date: 1978

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00396347
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: SAE 780686, HS-025 555U
  • Contract Numbers: NAS-7-100
  • Files: HSL, USDOT
  • Created Date: Aug 31 1985 12:00AM