Combustion phasing is the main obstacle to the development of controlled auto-ignition based (CAI) engines to achieve low emissions and low fuel consumption operation. Fuel combinations with substantial differences in reactivity, such as diesel/compressed natural gas (CNG), show desirable combustion outputs and demonstrate great possibility in controlling the combustion. This paper discusses a control method for diesel/CNG mixture combustion with a variation of fuel composition and fuel stratification levels. The experiments were carried out in a constant volume combustion chamber with both fuels directly injected into the chamber. The mixture composition was varied from 0 to 100% CNG/diesel at lambda 1 while the fuel stratification level was controlled by the injection phasing between the two fuels, with gaps between injections ranging from 0 to 20 ms. The results demonstrated the suppressing effect of CNG on the diesel combustion, especially at the early combustion stages. However, CNG significantly enhanced the combustion performance of the diesel in the later stages. Injection gaps, on the other hand, showed particular behavior depending on mixture composition. Injection gaps show less effect on combustion phasing but a significant effect on the combustion output for higher diesel percentage (≥70%), while it is contradictive for lower diesel percentage (<70%).
The main concern regarding on the spark plug usage is their ignition efficiency and lifetime capabilities. This article reviews on the spark plug engine profile in a spark ignition. An intelligent practical approach needs to be developed to be the indicator to know when the spark plug should be changed. Due to its promising effect on the spark ignition engine, the study of spark plugs profile is increasing day by day. For safety, mechanical vibration of a vehicle is a very important phenomenon. Moreover, it specifically affects passenger comfort in some applications. Due to the effects on vehicle structure components and passenger comfort as well as safety, the mechanical vibration through the spark ignition engine has acquired great significance. However, there are many problems in researching existing running engines with a spark ignition system, such as slower ignition, increased cyclic variance and possible misfire. The higher spark energy will improve the ignitibility, but due to electrode corrosion, the life of the spark plug will decrease, and electrodes serve as a sink of thermal energy that will affect the spark plug’s health. For instance, the conditions such as the spark plug gap, the plug thickness and the carbon dissipated on the spark plug that influences the output of a spark ignition, are highlighted in this article.
A linear engine type with piston assembly that swings between two oppositely placed combustion chambers considered in this study. The study investigated the effect of injection timing on starting of the engine. The injection position varied at five different positions (17mm to 27mm) before the maximum switching limit of the engine reached. It was observed that advancing the injection position in free-piston engine slows down the compression stroke and increases the combustion duration. Furthermore, lower peak pressure and rate of heat release occurred at 17 mm, 20 mm, and 23 mm injection timing. Relatively stable operation of the engine was achieved at 25 mm.
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