National Academies Press: OpenBook

NOX Emission Controls for Heavy-Duty Vehicles: Toward Meeting a 1986 Standard (1981)

Chapter: APPENDIX D: GLOSSARY OF TECHNICAL TERMS

« Previous: APPENDIX C: CERTIFICATION TEST CYCLES FOR HEAVY-DUTY ENGINES
Suggested Citation:"APPENDIX D: GLOSSARY OF TECHNICAL TERMS." National Research Council. 1981. NOX Emission Controls for Heavy-Duty Vehicles: Toward Meeting a 1986 Standard. Washington, DC: The National Academies Press. doi: 10.17226/19741.
×
Page 110
Suggested Citation:"APPENDIX D: GLOSSARY OF TECHNICAL TERMS." National Research Council. 1981. NOX Emission Controls for Heavy-Duty Vehicles: Toward Meeting a 1986 Standard. Washington, DC: The National Academies Press. doi: 10.17226/19741.
×
Page 111

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

APPENDIX D GLOSSARY OF TECHNICAL TERMS AIR/FUEL RATIO: Ratio of air to fuel, by weight, in a combustion process. BRAKE-SPECIFIC QUANTITY: The prefix "brake-specific" denotes a measure of some quantity divided by the power delivered by the engine. The total power generated in the engine is called the indicated power. The net or brake power output of the engine equals the indicated power minus the power required to overcome engine friction. CATALYTIC CONVERTER: Device in the exhaust systems of vehicles with spark-ignition engines, containing a catalyst to aid in reducing emissions. (See oxidizing converter and three-way converter.) CETANE INDEX: Value dervied from an empirical method for finding the cetane number of a diesel fuel, based on fuel's density and mid-boiling point. CETANE NUMBER: Equivalent percentage by volume of cetane (= n-hexadecane, cetane number l00) in a mixture with alphamethylnapthyene (cetane number O); indicates the relative ignitibility of the fuel upon in- jection into the engine cylinder. COMPRESSION RATIO: Ratio between the volume above the piston when it is at bottom dead center to the volume above the piston when it is at top dead center. DYNAMOMETER: Device for testing engines. Assures power output from the engine and provides measurement of engine torque. EGR: Exhaust gas recirculation. Recirculation of a portion of the engine exhaust gases into the air intake, to control NOX emissions. ENGINE LOAD: General term referring to power or torque demand on the engine. ENGINE SPEED: Crankshaft revolutions per minute. FOUR-STROKE CYCLE: Engine cycle consisting of a downward intake stroke, an upward compression stroke, a downward power stroke, and an upward exhaust stroke. HEAVY-DUTY: Applications more severe than passenger car service. Usually applied to service in buses or trucks in excess of 8,500 pounds gross weight rating. ll0

HI HYDROCARBONS: Substances whose molecules are made solely from hydrogen and carbon atoms, with multiple carbon atoms linked to one another and with hydrogen atoms attached to the carbon atoms. MANIFOLD: Branched-pipe passage device that connects openings from each cylinder to a common opening. OXIDATION CATALYST: Catalyst, operating with oxygen in the exhaust gas, designed to oxidize exhaust carbon monoxide and hydrocarbons to carbon dioxide and water. PERFORMANCE: General descriptive term covering engine power output, durability, and driveability. QUENCH: Cool to temperatures at which the flame will go out. SAC VOLUME: Volume of the space in the top of a diesel fuel injector. Zero volume is the ideal design objective for low hydrocarbon emissions. SPARK-IGNITION ENGINE: An engine whose combustion is started by an arc across the spark plug electrodes. SPARK TIMING: Point in an engine's crankshaft rotation at which the spark plug is fired. STEADY STATE: Constant operating conditions with no variation in speed or load. STEADY-STATE TEST: Current test cycle for heavy-duty engines. TEST CYCLE: The specific sequence of speed and load conditions at which an engine is run for measurement of emissions. TEST PROCEDURES: Full set of procedures for testing engines to determine compliance with emission standards. THERMAL EFFICIENCY: Energy output (of the engine, for example) divided by the energy in the fuel used. THREE-WAY CATALYST: Exhaust treatment catalyst designed for simultaneous removal of carbon monoxide, hydrocarbons and oxides of nitrogen. TORQUE: Measure of the twisting moment on a shaft. TRANSIENT TEST CYCLE: The new test cycle for heavy-duty engines, effective in l984.

Next: APPENDIX E: STATEMENT OF GEORGE R. HEATON, JR. »
NOX Emission Controls for Heavy-Duty Vehicles: Toward Meeting a 1986 Standard Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF
  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!