Investigative Research of Diesel/ethanol Advanced Combustion Strategies: A Comparison of Premixed Charge Compression Ignition (PCCI) and Direct Dual Fuel Stratification (DDFS)

Direct Dual Fuel Stratification (DDFS) is a new low-temperature combustion (LTC) approach that employs dual fuel direct injection in the combustion chamber. In this method, a relatively small proportion of diesel fuel was pre-injected and utilized to activate the burning of the premixed charge followed by direct injection of a diesel/ ethanol mixture (75% diesel, 25% ethanol by volume) into the combustion chamber near TDC. The DDFS approach generates a lower reactivity charge in the central sector of the combustion chamber and a stronger reactivity charge along the wall. For the examination of combustion vibrations and acoustic, a new technique dependent on the fast Fourier transform (FFT) of the cylinder vibration statistics was used. Whereas the PCCI combustion technique is more likely to cause knocking than the typical diesel CI, the results show that charge stratification in DDFS combustion does have a good effect in reducing vibration intensity. Owing to the improved controllability of the start of combustion and burning period, DDFS combustion attained a brake thermal effi-ciency (BTE) of 51%, which was larger than CI and PCCI. DDFS shows ultra-low nitrogen oxide (NOx) (below 1 g/ kW-h), mild carbon monoxide (CO) (below 6 g/kW-h), and unburned hydrocarbons (UHC) emissions. Because of the higher thermal efficiency and a decreased carbon source due to presence of ethanol, DFFS combustion could produce lower CO levels by up to 34% when compared to PCCI.