Abstract
Due to the recent global increase in fuel prices, to reduce emissions from ground transportation and improve urban air quality, it is necessary to improve fuel efficiency and reduce emissions. Water, methanol, and a mixture of the two were added at the pre-intercooler position to keep the same charge and cooling of the original rich mixture, reduce BSFC and increase ITE, and promote combustion. The methanol/water mixing volume ratios of different fuel injection strategies were compared to find the best balance between fuel consumption, performance, and emission trends. By simulating the combustion mechanism of methanol, water, and diesel mixed through the Chemkin system, the ignition delay, temperature change, and the generation rate of the hydroxyl group (−OH) in the reaction process were analyzed. Furthermore, the performance and emission of the engine were analyzed in combination with the actual experiment process. This paper studied the application of different concentration ratios of the water–methanol–diesel mixture in engines. Five concentration ratios of water–methanol blending were injected into the engine at different injection ratios at the pre-intercooler position, such as 100% methanol, 90% methanol/10% water, 60% methanol/40% water, 30% methanol/70% water, 100% water was used. With different volume ratios of premixes, the combustion rate and combustion efficiency were affected by droplet extinguishment, flashing, or explosion, resulting in changes in combustion temperature and affecting engine performance and emissions. In this article, the injection carryout at the pre-intercooler position of the intake port indicated thermal efficiency increase and a brake specific fuel consumption rate decrease with the increase of water–methanol concentration, and reduce CO, UHC, and nitrogen oxide emissions. In particular, when 60% methanol and 40% water were added, it was found that the ignition delay was the shortest and the cylinder pressure was the largest, but the heat release rate was indeed the lowest.
Highlights
Simulation showing that the addition of methanol prolongs the ignition delay
The ignition delay was measured by connecting the cylinder pressure sensor and the When water was injected, methanol snatched −OH from the water molecules, reducing combustion analyzer to the computer through the CAN line, using the combustion analysis the inhibition of −OH growth in diesel, and the addition of water diluted the concentration software to collect the cumulative heat release rate data, and integrate the heat release rate of methanol and alleviated the impact of methanol’s low calorific value on the mixed fuel
As methanol was injected into the diesel engine, the −OH molecule in the reaction with the diesel was robbed for the first time, which reduced the reaction efficiency of the diesel
Summary
The water–methanol–diesel mixed fuel was one of the key technologies used to reduce the pressure, heat release rate, and emissions during the combustion of diesel engines [1,2]. Compared with diesel, when the methanol/water mixture was injected through the front of the intercooler to increase the mixed fuel charge, it played a cooling role through heat conversion and reduced exhaust emissions [3,4]. The latent heat of vaporization of water was higher than that of methanol [5], after the two fuels were mixed, it reduced the formation of soot [6] during the combustion process, reduced in-cylinder pressure, and increased HRR. Several researchers conducted water injection experiments on small supercharged engines and observed improvements in full-load thermal efficiency, reduction in exhaust gas temperature, and improvement in braking specific fuel consumption [7,8,9,10]
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