Experimental study on the effect of the thermal barrier coated (TBC) piston on combustion of gasoline compression ignition (GCI)

Abstract

Gasoline compression ignition (GCI) has the advantage in achieving high thermal efficiency and low emissions simultaneously. However, the difficulty in realizing stable compression combustion at low load is a major problem that GCI faces and needs to be addressed. In addition, improving thermal efficiency of internal combustion engine is also an important research topic, especially for satisfying low carbon goals in the future. Therefore, to explore strategies to improve combustion stability and thermal efficiency of GCI combustion, the low thermal conductivity ceramics (MgZrO3) was coated on the top surface and combustion chamber of the piston to reduce the thermal conductivity, then achieving the purpose of increasing the in-cylinder temperature and reducing the heat transfer. The experiment was conducted under different loads conditions to investigate the effect of thermal barrier coated (TBC) piston on GCI combustion. The result shows that the indicated thermal efficiency of GCI can be increased by 6.4% with the TBC piston at low load, meanwhile the THC and CO emissions are also reduced effectively. Furthermore, employing TBC piston can significantly improve the combustion stability of low load GCI combustion and therefore has great potential to extend lower load operation. However, the effect of TBC piston on improving indicated thermal efficiency decreases as engine load increases, and the difference in combustion between the TBC piston and piston without TBC is fairly small under high load condition. Compared to piston without TBC, the indicated thermal efficiency of TBC piston is higher and change slightly as EGR rate increases. With the TBC piston, lower NOx and soot emissions can be obtained while the indicated thermal efficiency remains at high value by introducing high EGR rate.