Relevance of Octane Sensitivity in heavily downsized Spark-Ignited Engines King Abdullah Univ. of Science and Tech

Format:

Book

Conference/Event

Author/Creator:

Singh, Eshan, author.

Contributor:

Gorbatenko, Inna

Mohammed, Abdulrahman

Sarathy, Mani

Conference Name:

15th International Conference on Engines & Vehicles (2021-09-12 : Capri, Italy)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2021

Summary:

Over the years, spark-ignition engine operation has changed significantly. This change is driven by many factors including changes in operating conditions. The variation in operating conditions impacts the state, and therefore, the auto-ignition of the end-gas. This variation in operating conditions can be quantified in terms of K-factor, which weights the relative contribution of Research Octane Number (RON) and Motor Octane Number (MON) to knocking tendency at any operating condition. The current study investigates the fuel requirements when operating an engine at different K values. A model engine was operated at varying load in GT-Power software, from naturally aspirated intake air to heavily boosted intake air pressure of 4 bar absolute. The pressure-temperature information from the model was used to calculate ignition delay times of the unburnt end-gas composed of a sensitive and non-sensitive gasoline fuel in ChemKin software. The results show that high octane sensitivity is desired at negative K values (operating at high intake air pressures). In contrast, zero octane sensitivity performed best at low load operation (positive K). Interestingly, the maximum benefit for using a sensitive fuel was achieved at an intake air pressure of 1.75 bar with diminishing returns at higher intake air pressure. Engine experiments were conducted in a CFR engine with two fuels of same RON 90: a blend of iso-octane (90% v/v) and n-heptane (10% v/v) and a blend of toluene (71.7% v/v) and n-heptane (28.3% v/v). Operating at highly boosted intake conditions confirmed the modeling results. The observations point to a lowered importance of octane sensitivity and an increase in K-factor as the engine downsizing trend continues in the future. The observations have implications for fuel design for heavily downsized engines

Notes:

Vendor supplied data

Publisher Number:

2021-24-0054

Access Restriction:

Restricted for use by site license