Influence of Hydrogen Rich Gas Addition on Performance Features of a Gasoline Direct Injection (GDI) Engine Operation

Abstract

In a practical sense, lean burning engines are limited by onset of engine misfiring as lean flammability limit of any fuel is approached. Hydrogen may be used to extend lean limit of conventional fuel in order to stabilize lean combustion. No nationwide distribution system exists for hydrogen and its storage as a high-pressure gas or cryogenic liquid. These potential difficulties can be avoided by generating hydrogen in an on board gas generator using partial oxidation method from hydrocarbon fuel. Plasma fuel reformer provides (PFR) electrical discharges at high temperature boosts partial oxidation reactions between gasoline and air, producing hydrogen-rich gas (H₂).

                The aim of the research was to extent the lean operation limit of GDI engine with supplementation of hydrogen rich gas from on board plasma fuel reformer (PFR). Performance tests were conducted on GDI engine under varied operating parameters such as air fuel ratio, spark timing and injection timings with definite fraction of hydrogen rich gas.   Engine lean burn limit could be extended by hydrogen addition because hydrogen fuel has broader burn limit and fast burn speed. 10%, 18%, and 30% hydrogen rich gas fraction extended the lean limit equivalence ratio 0.68, 0.62, and 0.52, respectively, where 0.58 is the lower limit equivalence ratio of Gasoline. Unburned HC emission decreased with increasing fraction of hydrogen addition irrespective of spark timing alterations. After optimizing spark timing to MBT, engine efficiency increased with increase of hydrogen fraction. NO_x emission for different hydrogen fraction showed little difference at the MBT spark timing.