Knock-limited loads for a set of surrogate gasolines all having nominal 100 research octane number (RON), approximately 11 octane sensitivity (S), and a heat of vaporization (HOV) range of 390 to 595 kJ/kg at 25°C were investigated. A single-cylinder spark-ignition engine derived from a General Motors Ecotec direct injection (DI) engine was used to perform load sweeps at a fixed intake air temperature (IAT) of 50 °C, as well as knock-limited load measurements across a range of IATs up to 90 °C. Both DI and pre-vaporized fuel (supplied by a fuel injector mounted far upstream of the intake valves and heated intake runner walls) experiments were performed to separate the chemical and thermal effects of the fuels’ knock resistance. The DI load sweeps at 50°C intake air temperature showed no effect of HOV on the knock-limited performance. The data suggest that HOV acts as a thermal contributor to S under the conditions studied. Measurement of knock-limited loads from the IAT sweeps for DI at late combustion phasing showed that a 40 vol% ethanol (E40) blend provided additional knock resistance at the highest temperatures, compared to a 20 vol% ethanol blend and hydrocarbon fuel with similar RON and S. Using the pre-vaporized fuel system, all the high S fuels produced nearly identical knock-limited loads at each temperature across the range of IATs studied. For these fuels RON ranged from 99.2 to 101.1 and S ranged from 9.4 to 12.2, with E40 having the lowest RON and highest S. The higher knock-limited loads for E40 at the highest IATs examined were consistent with the slightly higher S for this fuel, and the lower engine operating condition K values arising from use of this fuel. The study highlights how fuel HOV can affect the temperature at intake valve closing, and consequently the pressure-temperature history of the end gas leading to more negative values of K, thereby enhancing the effect of S on knock resistance.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Effects of Heat of Vaporization and Octane Sensitivity on Knock-Limited Spark Ignition Engine Performance


    Additional title:

    Sae Technical Papers


    Contributors:

    Conference:

    WCX World Congress Experience ; 2018



    Publication date :

    2018-04-03




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    Effects of Heat of Vaporization and Octane Sensitivity on Knock-Limited Spark Ignition Engine Performance

    Ratcliff, Matthew A. / Burton, Jonathan / Sindler, Petr et al. | British Library Conference Proceedings | 2018


    Knock effects on spark-ignition engine emission and performance

    Kaelblein,T. / Jeong,Y.I. / Rhee,K.T. et al. | Automotive engineering | 1990


    Knock effects on spark-ignition engine emission and performance

    Kaelblein, T. / Jeong, Y.I. / Rhee, K.T. | Tema Archive | 1990


    Knock Effects on Spark-ignition Engine Emission and Performance

    Rhee, K. T. / Kaelblein, Thomas / Jeong, Y. 1. | SAE Technical Papers | 1990


    Control of Fuel Octane for Knock Mitigation on a Dual-Fuel Spark-Ignition Engine

    Anderson, Eric / Baranski, Jacob / Hoke, John et al. | SAE Technical Papers | 2013