In the early 1970s the U.S. set emission limits for hydrocarbons, carbon monoxide and nitrogen oxides from gasoline and diesel vehicles, for evaporative emissions from gasoline cars and for smoke from heavy-duty diesel engines. The requirement for significant reduction of emissions brought about the computer-controlled automobile about 15 years sooner than it might otherwise have occurred. New U.S. restrictions on particulates, nitrogen oxides and hydrocarbons may now trigger the same R&D on diesel engines. For emissions purposes the heavy-duty engine is one used on a vehicle of over 8500 lb gross weight or with over 45 sq ft frontal area. This involves engines from about 100 to over 400 hp. Standards to 1985 have been met for smoke through engine design modification and adjustment, not through fuel modification or exhaust after-treatment. The 1988 regulations require heavy-duty diesels to meet a limit on particulate emissions and on nitrogen oxides and these may still require no trap or filter on the exhaust. Beginning in 1991, some sort of trap will be needed as well as alternative fuels. Methanol is a possibility, burned in a compression-ignition engine with a glow or spark plug for start and part-load operation. To meet nitrogen limits, charge air cooling will be necessary with perhaps some exhaust gas recirculation. City bus limits for 1991 will require efficient particulate traps capable of filtering out more than 80 percent of solids. An alternative would be engines refitted to burn methanol with an oxidation catalyst for final removal of undersirable material from exhaust. By 1994 all diesel engines will have to meet such standards. Ultimately some new technology could evolve from computer controls needed to meet 1991 requirements. Ultimately all this technology may be valuable for particulate control and fuel efficiency on larger diesel engines (over 500 hp) used on locomotives, ships and in stationary applications.

  • Corporate Authors:

    Southwest Research Institute

    Department of Communications, P.O. Drawer 28510
    San Antonio, TX  United States  78284
  • Authors:
  • Publication Date: 1985-9

Media Info

  • Features: Photos;
  • Pagination: p. 2-8
  • Serial:
    • Technology Today
    • Volume: 6
    • Issue Number: 3
    • Publisher: Southwest Research Institute

Subject/Index Terms

Filing Info

  • Accession Number: 00451136
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 30 1985 12:00AM