High Injection Pressure Impact on a Direct Injection Diesel Engine

Abstract

Diesel engines are the primary source of power for heavy duty vehicles; diesel engines have better fuel economy than equivalent gasoline engines and produce less green house gas emission. On the other hand, formation of smoke due to diffusion combustion and emission of oxides of nitrogen released due to high combustion temperatures are the major limitations of the existing diesel engine designs. Diesel engine manufacturers have to address these most critical situations to meet the future emissions regulations whilst improving performance and fuel economy at a minimal cost. The fuel economy, increased dynamic response and strict exhaust emission regulations resulted in invention of new technology development required improving the diesel engine performance along with exhaust emissions reduction. These improvements are made possible with new fueling technologies by improvements in combustion process through increased injection pressure. High pressure fuel injection results in better fuel atomisation and improves the fuel/air mixing to promote complete combustion, thereby increasing the fuel efficiency with emission control. The objective of this paper is to investigate the effect of fuel injection pressure on performance, fuel consumption and emission of a diesel engine. A study was done on a single cylinder 4 stroke direct injection diesel engine and the performance and emission characteristics were presented graphically. Based on experimental results, the best performance was found at 220 bar fuel injection pressure.

Significant impacts of injection parameters on marine diesel engines

“…Visible smoke as the function of injection timing and pressure [7]. However, as shown in Figure 11, the NOx emission is also higher with a higher injection pressure.…”

“…Figure 10. NO concentration as the function of time and combustion temperature [7]. Figure 10 shows that the higher the combustion temperature, the higher the concentration of NOx will be.…”

“…As a result, the system employed the so-called circulating fuel: the fuel can flow through the whole injection system continuously even the engine is stopped. To obtain this ability, the injection pump has a circulation port from which the hot fuel can be discharged [7].…”

“…This will generate more NOx emissions, as shown in Figure 11. [7]. High peak combustion temperature can introduce too much heat stress onto the piston crown.…”

“…Since the piston is cooled by the circulation of lubricating oil inside the piston crown, high temperature will break down the lube oil, and the carbon soot formed will deposit on the cooling surface. This, in turn, increases the surface heat transfer coefficient, which means insufficient piston cooling and can result in cracks in the piston [7].…”