Effect of internal and external EGR on cyclic variability and emissions of a spark ignition two-stroke cycle gasoline engine

Abstract

Conventional two-stroke cycle engine suffers from typical drawbacks including lower combustion efficiency and excessive emissions of uHC and CO which are largely due to low in-cylinder average charge temperature at low load and speed regions of engine operating conditions. Utilising the hot burned Exhaust Gas Recirculation (EGR) technique can boost the in-cylinder average charge temperature of the engine. The influence of hot burned gases applied by means of both Internal EGR and External EGR strategies on the combustion stability and exhaust gas emission of a single-cylinder twostroke cycle engine running at low-load and mid-load of operating conditions was investigated experimentally along with simulation works using 1-D engine simulation code. The results indicated that both In-EGR and Ex-EGR improved the combustion stability (lower misfire cycle) and decreased the concentrations of uHC and CO emissions, specifically at low speed region; however, NOx concentration was increased. At Internal EGR setting of 30%, the Coefficient of Variation for maximum in-cylinder pressure (COVPmax) reached the minimum by 5.64 while when External EGR percentage was 25%, COVPmax approached about 6.67 at the mid-speed (2000 rpm) of engine operating condition.

Application of The Chain Code and Fourier Analysis Techniques for The Investigation of Wrinkles and Distortions on Early Flames

“…A higher degree of wrinkles could be exhibited with lean fuel-air due to the relatively lower burn rate as compared to the wrinkling rate caused by turbulence. Then again, increasing of the engine speed could increase the turbulence intensity inside the cylinder [29,30], which facilitates the flame wrinkles formation [31]. Therefore, it can be affirmed that the trade-off between the fuel-air mixture leanness and the degree of turbulence caused as a result of variation of engine operating speed at the time of ignition is the determinant factors of the level of the early flames shown in Figure 11.…”

Determining the characteristics for the rational adjusting of an fuel-air mixture composition in a two-stroke engine with internal carburation

“…The use of DFI and exhaust gas recirculation is one of the promising ways to reduce fuel consumption and emissions of harmful substances from exhaust gases in a two-stroke SIE [24,25]. However, the issues connected with the change of the amount of recirculated exhaust gas relate to a specific method of organizing the operating process and cannot be fully extended to other operating processes that differ from it.…”

The Influence of Fuel Pump Pressure Variations on the Performance of 2-Stroke Gasoline Direct Injection Engines

“…So, for vehicle applications, especially motorcycles, a 2-stroke gasoline engine is needed which is environmentally friendly and has minimal pollution, without sacrificing performance and fuel economy. Several attempts have been made to reduce exhaust emissions from 2-stroke gasoline engines, including using Exhaust Gas Recirculating (EGR), but this has not been satisfactory because the results are affected by the rate of gas entering and exiting the EGR system (Andwari et al, 2017).…”