In order to reduce NOx emission and increase the brake thermal efficiency of a stationary diesel engine, a new prechamber, which is placed at the center of a cylinder head and has a smaller volume than conventional prechamber, was installed in a single cylinder diesel engine with a 170mm bore and 180mm stroke, and it was tested to investigate its potential. The high injection pressure, and improvement of prechamber and main chamber promoted combustion and improved the brake thermal efficiency and smoke emission. The combustion temperature and thus the NOx emission were reduced by realizing the enlargement of jet passage area. A NOx concentration of 184ppm (13% excess O2) at the brake thermal efficiency of 37% was obtained with this new prechamber combustion system.
