CAJ | 학술논문

为了防止某些工况下爆震的发生,该文在不改变4B26增压柴油机结构的前提下,采用进气甲醇电控喷射,实现甲醇/柴油双燃料燃烧,分析了进气预混掺烧甲醇/柴油双燃料发动机的燃烧过程.试验结果表明,低负荷时随着甲醇掺烧比例的增大,最大爆发压力、缸内平均温度和放热率峰值略有降低,燃烧始点推迟,燃烧持续期变化不明显;高负荷时,随着甲醇掺烧比例的增大,滞燃期缩短,燃烧终点提前,定容放热比例增大,最大爆发压力和放热率峰值明显增加,缸内平均温度略有升高;与燃烧柴油相比,在最大扭矩转速、80%负荷时,掺烧50%甲醇的最大爆发压力增加了12.1%,放热率峰值增加了37.7%.研究结果确定了不同负荷的甲醇掺烧比例变化范围,为甲醇喷射控制策略的优化提供了依据.
위료방지모사공황하폭진적발생,해문재불개변4B26증압시유궤결구적전제하,채용진기갑순전공분사,실현갑순/시유쌍연료연소,분석료진기예혼참소갑순/시유쌍연료발동궤적연소과정.시험결과표명,저부하시수착갑순참소비례적증대,최대폭발압력、항내평균온도화방열솔봉치략유강저,연소시점추지,연소지속기변화불명현;고부하시,수착갑순참소비례적증대,체연기축단,연소종점제전,정용방열비례증대,최대폭발압력화방열솔봉치명현증가,항내평균온도략유승고;여연소시유상비,재최대뉴구전속、80%부하시,참소50%갑순적최대폭발압력증가료12.1%,방열솔봉치증가료37.7%.연구결과학정료불동부하적갑순참소비례변화범위,위갑순분사공제책략적우화제공료의거.
@@@@In recent years, environment concerns and depletion in petroleum resources have forced researchers to concentrate on exploiting renewable alternatives fuels. As a renewable and alternative fuel, methanol has gained great attendance. As for the application of methanol on compression ignition engines, researchers have focused on partial replacement of diesel with methanol, either blended with diesel or injected into the air intake. Due to the poor miscibility of diesel and methanol, an additive has to be added to form steady methanol/diesel blends. However, majority of these additives have bad influence on NOX emission. Methanol and diesel can also be applied separately to the engine. Dual injection system is one method, which is difficult and expensive to develop. Compared with other methods, intake premixed methanol is more flexible in operation and has greater potential to applied to practical application. In this paper, the methanol injection system was optimally designed according to the former investigation on air-methanol mixture formation inside internal combustion engine. However, previous research results showed that severe knock would happen at high load with high proportion of methanol. In addition, the intake charge temperature declined, owing to the high level of methanol vaporization latent heat. Thirdly, with the addition of methanol, high temperature and low temperature exothermic reaction were delayed, and the ignition delay of dual fuel was prolonged. The premixed methanol injection was controlled by intake manifold electrically system, and the combustion process of methanol/diesel dual fuel was experimentally investigated. Based on the experimental results, the optimization and application of methanol injection system were proposed, and make sure that the output power of optimized dual engine hardly changed. The experimental research was carried out on 4B26 turbocharged diesel engine. The tests were conducted at four different methanol proportion (0, 30%, 40%, and 50%) by changing the methanol injection pulse width. All tests were conducted at two different loads (30%, 80%) at constant engine speed of 2200 rpm. The experimental test results showed that at low load, the peak heat release rate hardly changed, the peak in-cylinder pressure, temperature and ignition delay significantly increased with the increase of premixed methanol proportion. At high load, the in-cylinder pressure, temperature, and peak heat release rate increased, the ignition delay and combustion duration period shortened. At the load of 80%and methanol proportion of 50%, compared with original diesel engine, the premixed burning amount increased, the peak pressure and release rate value of dual fuel increased by 12.1%and 37.7%respectively. It is necessary to optimize the control strategy of methanol/diesel dual engine. According to the influence of dual engine fueled with different methanol proportion on combustion process, the range of methanol proportion was proposed. At the maximum torque speed, the 15%-55% methanol proportion was applicable under different operating condition. High proportion of methanol was available at low load. Nevertheless, with increase of engine load, the methanol proportion has to be strictly controlled. At the load of 80%, because of the limitation of knock, the proportion of methanol should be less than 15%.