Review of Hydrogen-Gasoline SI Dual Fuel Engines: Engine Performance and Emission

Rapid depletion of conventional fossil fuels and increasing environmental concern are demanding an urgent carry out for research to find an alternate fuel which meets the fuel demand with minimum environmental impacts. Hydrogen is considered as one of the important fuel in the near future which meets the above alarming problems. Hydrogen–gasoline dual fuel engines use hydrogen as primary fuel and gasoline as secondary fuel. In this review paper, the combustion performance, emission, and cyclic variation characteristics of a hydrogen–gasoline dual fuel engine have been critically analyzed. According to scientific literature, hydrogen–gasoline dual fuel engines have a good thermal efficiency at low and partial loads, but the performance deteriorates at high loads. Hydrogen direct injection with gasoline port fuel injection is the optimum configuration for dual fuel engine operating on hydrogen and gasoline. This configuration shows superior result in mitigating the abnormal combustion, but experiences high NOx emission. Employing EGR showed a maximum reduction of 77.8% of NOx emission with a EGR flowrate of 18%, further increment in flowrate leads to combustion instability. An overview on hydrogen production and carbon footprint related with hydrogen production is also included. This review paper aims to provide comprehensive findings from past works associated with hydrogen–gasoline dual fuel approach in a spark ignition engine