To reduce emissions of LPG engines in practical conditions

a typical LPG engine used for Guangzhou bus was taken as the research object and its emission characteristics were studied through a bench test system considering practical road conditions. With the relationship among engine emissions

emission control parameters and emission characteristics as a basis and by design of experiments (DoE)

a statistics mathematical model of the engine was established

with which main emission control parameters were optimized combining with multi objective optimization. The control parameters before and after optimization were input into the one-dimensional simulation model of the LPG engine to carry out engine performance simulation. The results show that after the optimization of the main control parameters

the HC and CO from the engine under experimental conditions are accumulatively reduced by 9.5% and 21.0% respectively and the maximum increase in torque is by 22.6%

but the accumulated emission of NO is increased by 2.7%.