Abstract
Research and/or Engineering Questions/Objective
Heavy regulations of fuel consumption and CO2 emissions became global issues. Therefore, downsizing turbo gasoline direct injection (T-GDI) is general trend. However, T-GDI engines still fall below regulations of fuel consumption and CO2 emissions for the coming year, 2020. Thermal efficiency of T-GDI engine can be enhanced by lean combustion. But, combustion instability is a main barrier of using lean combustion on T-GDI engines. Hydrogen has features that can ease combustion instability on lean condition of T-GDI engines. Thus, the objective of this study was to investigate feasibility and advantage of gasoline reformer on T-GDI engines at lean and high EGR rate to improve combustion stability.
Methodology
Earlier analysis of the effect of hydrogen on gasoline combustion has resulted on pure hydrogen which was supplied from hydrogen tank. However, in practice, hydrogen tank is hard to be installed on real car. Thus, onboard reforming is practical method to supply hydrogen to cylinders of engine on car. In this study, investigating feasibility and advantage of gasoline reformer has been carried out on TGDI engine. Excess air ratio, EGR rate and fuel injection to reformer were varied.
Results
In the paper results of burn duration, combustion stability, indicated thermal efficiency and hydrogen and CO concentration in reformed gas will be presented. The main finding is possibility of gasoline reformer to improve combustion characteristics of T-GDI engine. Due to hydrogen which was reformed by gasoline reformer, CA0-10 and CA10-90 was reduced. In addition COV of IMEP decreased and Indicated Thermal Efficiency was slightly improved. Thus, application of hydrogen addition with gasoline reformer on T-GDI engine has a possibility to improve thermal efficiency to satisfy future regulations of fuel consumption.
Limitations of this study
An important limitation of this study is an optimization of reforming system.
What does the paper offer that is new in the field including in comparison to other work?
Recently, T-GDI engine is the general trend. However, most of existing research was done on pure hydrogen which was supplied from hydrogen tank. Thus, effect of reformed hydrogen needs to be studied.
Conclusions
Reformed hydrogen can improve combustion characteristics and ease combustion instability of T-GDI engine on lean condition. Thus, gasoline reformer is a possible and practical way to improve thermal efficiency of T-GDI engine by reformed hydrogen addition.
Key Words : Reformer; Gasoline reforming; Turbo gasoline direct injection; T-GDI; Hydrogen