Aiming to achieve the goal of efficient and clean combustion in internal combustion engines, simulations are used to change the physicochemical properties and molecular configuration of fuels by adding oxygenated fuels such as alcohols, esters, ethers, etc., so as to achieve the purpose of improving combustion and reducing emissions. In this paper, blends of oxygenated fuels, including n-butanol, DME, DMC, and diesel fuel with different oxygen-containing functional groups, were selected for simulation to reveal the chemical mechanisms of fuel oxygen on combustion and pollutant generation in the combustion system and to deeply explore the mechanism and influence law of the different forms of oxygen bonding on the generation and oxidation of carbon smoke. At the same fuel oxygen content, the differences in the fuel physicochemical properties and reaction paths resulted in different effects of the different oxygenated fuels on the in-cylinder oxidative activity and different inhibition abilities of carbon smoke precursors. Compared with pure diesel, n-butanol, and DME, which promoted OH generation, DMC inhibited OH generation, so the oxidation activity of diesel/n-butanol was the highest, and that of diesel/DMC was the lowest; meanwhile, the two O atoms in the DMC molecule formed CO₂ with one C atom, which reduced the utilization efficiency of the O atoms, whereas each O atom in the n-butanol and DME fuels took away one C atom, so the utilization efficiency of O atoms was higher. The individual oxygenated fuels themselves had different abilities to contribute to carbon smoke precursors, and the above combined factors led to reductions of 8.7%, 32.6%, and 85.4% in soot emissions from the addition of DMC, DME, and n-butanol compared to pure diesel fuel, respectively, at the same oxygen content. At a medium load, the addition of n-butanol, DME, and DMC reduced NOx emissions by 0.5%, 1.7%, and 3.3%, respectively. Thus, it is shown that DMC has a more significant effect on NOx emission reduction.

Targeting the performance optimization of an automotive diesel engine under transient operation conditions, in this research, the effect of several non-linear loading strategies on diesel performance have been experimentally analyzed using a heavy-duty turbocharged diesel engine running under transient conditions based on the constant 1650 r/min speed, the load is increased from 10% to 100% in a 5 s transition time The results show that the larger the early loading rate and change point load, the better the dynamic torque response. The peak values of smoke and CO and the transient average of brake specific fuel consumption (BSFC), soot and CO can be decreased by increasing the early loading rate by the loading strategies with the appropriate change point load during transient operation. However, combustion deteriorates under the loading process with an overlarge change point load, causing emissions to increase, and the larger the early loading rate, the worse the worsening. Based on the trade-off consisting of torque dynamic response, transient total and transient average of the BSFC and brake specific emissions, peak values of smoke and CO emissions, it is concluded that the loading strategy with the early loading rate is the 50% load per second and the change point load in the 25% load is the most suitable in these strategies.

The effects of cetane number (CN) coupled with pilot injection ratio and pilot injection timing on the combustion and emission characteristics of a four-cylinder diesel engine were investigated. The results showed that as the pilot injection ratio increases, the peak cylinder gas pressure (CGP) increases, and the peak of heat release rate (HRR) increases accordingly; the coupled CN increases, the brake specific fuel consumption (BSFC) decreases, and the brake thermal efficiency (BTE) increases; CO and HC emissions increase; and NO _x emissions increase. In addition, the number concentration and total mass of particulate matter (PM) decrease with the increasing pilot injection ratio. Only when the pilot injection ratio reaches 20% does the fuel produce pilot injection heat release. The ignition delay time (ID) and combustion duration (CD) are redefined for the pilot injection heat release operating conditions. With the delay of the pilot injection timing, the peak CGP increases, the coupled CN increases, the BTE increases, the BSFC decreases, CO and HC emissions increase, and NO _x emissions decrease. With the delay of the pilot injection timing, the number concentration and total mass of PM decrease. In addition, no pilot injection heat release was generated for any of the five fuels at pilot injection timings from 30°CA BTDC to 45°CA BTDC.

In recent years, due to the strengthening of our countrys comprehensive strength, the rapid development of science and technology and artificial intelligence has also attracted peoples attention. Artificial intelligence is a highly applicable subject, which has very good applications in power systems. In the experiment, the open circuit voltage method and the ampere-hour integration method are used to estimate the SOC of the lithium battery and the particle swarm energy management algorithm is used to allocate the output power of the fuel cell and the lithium battery. The particle swarm algorithm module calls the dual source hybrid power system module through the sim function to convert the actual value input in the system into a fuzzy quantity suitable for fuzzy control. The energy management strategy based on particle swarm optimization and fuzzy control was tested based on working conditions under the comprehensive test bench. Finally, the matching of the hybrid system is analyzed from the structure, component parameters, control strategy, and driving cycle of the vehicle. The experimental data show that the total fuel consumption of the three sets of experiments is averaged to get a fuel consumption rate of 26.3m³/100km for the hybrid city bus under the optimized energy management strategy. The results show that the real-time energy management strategy based on particle swarm algorithm can significantly improve the real-time performance of traditional instantaneous energy management strategies while reducing fuel consumption.

In this article, the critical spontaneous ignition temperature of both hydrocarbon and alcohol fuel was acquired on a constant volume combustion bomb platform by slowly heating the inner charges, and then followed by using the CHEMKIN-PRO software to simulate the auto-ignition-dominated characteristic and parameter sensitivity of the two kinds of fuels. Results revealed that in different conditions, the critical spontaneous ignition temperature of methanol changed dramatically, with a maximum temperature of 50 K, while the counterpart temperature of n-heptane remained an invariable value of 553 K within a large changeable scope of temperature, and only a maximum temperature of 10 K was observed. The maximum difference of spontaneous ignition temperature between methanol and n-heptane reached 270 K. At the same time, a minimum difference of 170 K was obtained as well. The complete reaction of methanol requires 5 steps, involving 6 components and 11 elementary reactions. However, for the comparative part-n-heptane, more than 20 main self-ignition reactions were involved, which indicated that the whole reaction process of n-heptane has more reaction pathway branches and it was much more complicated compared to methanol. The differences of the reaction pathways triggered a considerable distinction of critical self-ignition temperature between the two charges, making a “step-by-step” spontaneous ignition combustion mode possible. In this way, a further high-efficient and clean combustion can be available to cater to much more stringent emission regulations in the future.