Development Of The Single-Cylinder Optical Engine For Low Conentration Gas

Our country is a leading coal country, CBM resources are very rich, its physicochemical property is suitable as alternative fuel of the engine to generator. In the coal exploiting process, the gassy equivalent to 13×109 m3 pure methane is mined per year. But over 60% of the gassy is discharged into air directly, because the concentration of the gassy is low. It creates the resources waste and the environmental pollution.The design of a single cylinder optical engine was completed, through reforming the 8300 coal bed methane engine of Zibo Diesel Engine Factory. The lubrication system, the mixture gas preparation, ignition, timing control system, CCD camera and data acquisition system and so on were designed. The results showed that:the combustion processes in the engine could be observed, and the flame images and pressure changes with the crank angle could be recorded; the single-cylinder optical engine can complete the expected experiment functions.Meanwhile, the quasi-dimensional model of the turbulent combustion in the cylinder was builded to process the test data. The variation of combustion velocity, fired gas temperature and flame propagation speed, when the press, excess air ratio and ignition timing changed,was calculated by this quasi-dimensional model.Comparing the experimental data with the calculation results of this model, show that: Compared with the lean mixture, the rich mixture enable more quickly combustion velocity, greater combustion heat release rate, higher maximum pressure and larger pressure rise rate, and temperature rise in-cylinder was more rapidly, the maximum temperature was also higher; At the equivalence ratio 1.1,the duration of combustion processes was shortest, the pressure rise rate and the explosion pressure were highest; At the equivalence ratio 1.0, the pressure rise rate at high speed was slightly larger that at low speed; At the equivalence ratio 0.8, the pressure rise rate at low speed was significantly larger that at high speed; Conclusively, whether the magnitude of rotational speed, when the equivalence ratio was less, the maximum pressure was smallest, and the ignition delay period was longer.