【作者】 董玉振；

【导师】 邓德乐； 刘永启； 李宗立； 李冬梅；

【作者基本信息】 山东理工大学 ， 动力机械及工程， 2010， 硕士

【摘要】 我国是煤炭资源大国,煤层气资源极为丰富,其理化特性非常适合作为内燃机的代用燃料,驱动发电机组发电。但是每年在煤炭开采过程中,产生的相当于130多亿m3纯甲烷的瓦斯中,有60%以上由于浓度太低,无法利用,被直接排入大气,造成了资源浪费和环境污染。本文完成了由淄博柴油机总公司提供的8300煤层气发动机改造成低浓度瓦斯单缸可视化发动机的设计工作,包括为之配备润滑系统、混合气配制系统、点火系统、时序控制系统、同步的数据采集系统和高速摄影系统及相关控制系统。并进行了初步的试验,结果表明：该装置能够观测到发动机缸内的燃烧过程,能够记录下燃烧过程照片和缸内压力随曲轴转角的变化规律；低浓度瓦斯单缸可视化发动机能够完成预期的试验功能。同时,针对低浓度瓦斯建立了发动机缸内准维双区湍流燃烧模型,分析处理试验数据。此模型能根据实测的燃烧压力曲线计算出层流燃烧速度、已燃气火焰温度及火焰传播速度等参数随压力、当量比、发动机转速、点火提前角的变化规律。通过试验数据与模型计算结果的对比分析,表明：浓混合气较稀混合气,燃烧速度更快,燃烧放热率也更大,使最高压力,压力上升率更大,缸内温度上升的速度加快,最高温度也越大。当量比为Φ=1.1时,燃烧过程历时最短,压力升高率最高,爆压也最高；当Φ=1.0时,高转速的压力升高率略大于低转速的升高率；当Φ=0.8时,反而低转速时的压力升高率明显高于高转速的升高率；总的来说,无论转速如何,Φ值较小的最高压力较小,燃烧过程滞后。更多还原

【Abstract】 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.更多还原