Effects of ammonia addition and variable valve timing on knocking and performance of ethanol pre-chamber engine with high compression ratio

To attain the objective of carbon neutrality, improving the compression ratio of engines and utilizing renewable alcohol fuels is imperative. However, challenges such as knock limit the use of high compression ratio engines under high-load stoichiometric combustion conditions. Turbulent injection ignition (TJI) is an efficient and clean combustion technology that can effectively suppress knock. In addition, ammonia addition and variable valve technology were also considered effective means to affect knock. It can further break through the limitation of knocking on the thermal efficiency of ethanol engines under high loads. Therefore, this article developed seven valve strategies to investigate how valve strategies and the ammonia energy ratio (AER) influence the performance and knocking of pre-chamber engine fueled with ethanol. It has been observed that adjusted valve timing and added ammonia effectively reduced MAPO. When the AER exceeded 20 %, it didn't knock under any conditions. With the increase of AER, the flame development was prolonged. The effect of valve timing on CA50 was not significant. By adjusting the valve timing and AER, the optimal ITE can be increased by 4.09 %. In addition, adding ammonia can effectively reduce CO emissions by up to 14.04 %. Adjusting valve timing can reduce NOx emissions by 17.07 %.