Secondly, the objective function is designed based on the excess air coefficient and the main steam pressure deviation signal.
The thickness of waste bed, the initial moisture content, the excessive air coefficient and the secondary air are the major factors that influence the combustion process.
The ignition delay times increase at first and then decrease with the increase of excess air coefficient ranging from 0.91 to 6.38.
A reasonable bed thickness and an adequate excessive air coefficient can keep a higher temperature, promote the burnout of combustibles, and consequently reduce the emission of dioxin pollutants.
The simulation results show that the presented method can effectively improve the response speed and keep the excess air coefficient in the optimal combustion interval.
During the tests, carried out in a test bed with a specially designed, electronically controlled LPG injection unit, the excess air coefficient was maintained within the range of 0.95 1.05 because the best emissions results are generally obtained in this range.
It is found that load factor has a great influence on nitrogen oxides and carbon monoxide emissions, but the effect is gradually disappeared when air coefficient is not less than 1.4.
When nozzle exit position is −3.0 mm, nozzle diameter is not less than 1.6 mm and air coefficient is not less than 1.4, the emissions of nitrogen oxides and carbon monoxide are less than 20 ppm and 50 ppm, respectively.
The effects of excess air coefficient, RGF, load and intake tumble on combustion rate are mainly reflected in SA (spark advance -10advance -10% duration rather than 10–90% combustion duration, and the sparatherance angle has lithan influence on SA-50% combustion duration.
On this basis, the semi-empirical models for combustion characteristic parameters were derived, and the quantitative relations between combustion characteristic parameters and engine operating parameters, including speed, load, spark advance angle and excess air coefficient, etc., have been built.
