Impact of Fuel Properties on GDI Injector Deposit Formation and Particulate Matter Emissions 2020-01-0388
Gasoline Direct Injection (GDI) engines show advantages in reducing fuel consumption and gaseous pollution emissions when compared to Port Fuel Injection (PFI) engines. However, particulate matter emissions are an essential issue for GDI engine development due to increasingly stringent worldwide emission regulations. Previous studies have shown that gasoline fuel compositions, as well as deposits formed in fuel injectors, can affect emissions in the GDI engine. In this work, the impact of gasoline fuel properties on injector deposit formation tendencies and the resulting effect on particulate matter emissions were investigated using a modern Chinese GDI engine. Six test fuels with different properties involving changes in olefins, aromatics, heavy aromatics (C9/C9+), T90 and deposit control additive (DCA) were blended based on the gasoline survey results in the Chinese gasoline fuel market and the China 6 gasoline fuel standard limits. A 1.0L 3-cylinder turbocharged GDI engine in the Chinese market was prepared and operated under steady-state condition (2000 rpm, 3 bar BMEP load) lasting for 55 hours to accumulate injector deposits. The injector flow rate loss and injection pulse width increase caused by injector deposits were obtained when different gasoline fuels were used. Meanwhile, the engine out particle number (PN) emissions were measured before, during and after the fouling tests. Test results indicated that fuel properties showed obvious impact on GDI injector deposit formation and the PN emissions increased significantly after injector deposit accumulation. Gasoline fuels with higher olefin, aromatic and heavy aromatic contents led to more deposits formed in GDI injectors and higher PN emissions, while fuel containing DCA was effective in reducing the formation of injector deposits and PN emissions. It was also observed that when fuel’s T90 reached 180 ℃ with increasing amount of heavy aromatics, injector fouling tendency was reduced, indicating the complex GDI injector deposit formation mechanism.
Wenbin Zhang, Xiao Ma, Lu Xinhui, Shijin Shuai, Kaihua Wu, James Macias, Yuan Shen, Chen Yang, Li Guan
Tsinghua University, Shell Technology, Ltd., Geely Powertrain Research Institute