Analysis of the Water Addition Efficiency on Knock Suppression for Different Octane Ratings
Paper in proceeding, 2020

Water injection can be applied to spark ignited gasoline engines to increase the Knock Limit Spark Advance and improve the thermal efficiency. The Knock Limit Spark Advance potential of 6 °CA to 11 °CA is shown by many research groups for EN228 gasoline fuel using experimental and simulation methods. The influence of water is multi-layered since it reduces the in-cylinder temperature by vaporization and higher heat capacity of the fresh gas, it changes the chemical equilibrium in the end gas and increases the ignition delay and decreases the laminar flame speed. The aim of this work is to extend the analysis of water addition to different octane ratings. The simulation method used for the analysis consists of a detailed reaction scheme for gasoline fuels, the Quasi-Dimensional Stochastic Reactor Model and the Detonation Diagram. The detailed reaction scheme is used to create the dual fuel laminar flame speed and combustion chemistry look-up tables. The Detonation Diagram is used as a novel approach in the Quasi-Dimensional Stochastic Reactor Model to evaluate the auto-ignition characteristic in the end gas and determine if it is a harmless deflagration or developing detonation. First, the Quasi-Dimensional Stochastic Reactor Model is trained for three engine operating points and a RON95 E10 fuel. Its performance is evaluated based on experimental results of a single cylinder research engine. Subsequently, different spark timings and water-fuel ratios are investigated for different Primary Reference Fuels. The results outline that water addition can effectively reduce the strength of auto-ignition in the end gas for different Primary Reference Fuels. Thereby, it can be stated that the reduction of the auto-ignition strength through water addition by 50-80 % water-fuel ratio for high octane number fuels corresponds to the spark timing delay of 6 °CA or an increase of research octane number by 10 points.

Author

T. Franken

Brandenburg University of Technology

L. Seidel

LOGE

Andrea Matrisciano

Chalmers, Mechanics and Maritime Sciences, Combustion and Propulsion Systems

F. Mauss

Brandenburg University of Technology

Andre Casal Kulzer

Porsche AG

Frank Schuerg

Porsche AG

SAE Technical Papers

0148-7191 (ISSN)

Vol. 2020-April April

SAE 2020 World Congress Experience, WCX 2020
Virtual; online, USA,

Subject Categories

Energy Engineering

Chemical Process Engineering

Other Chemical Engineering

DOI

10.4271/2020-01-0551

More information

Latest update

7/9/2021 1