Comparative assessment of engine performance and emissions fueled with three different biodiesel generations.

Emissions from biodiesel combustion depend on types of feedstocks. This study investigated physicochemical properties of biodiesels in three various feedstocks generations and the effect of them on emissions and performance of the unmodified engine. Methyl esters from Eruca sativa (ES) which has crops with short production cycle and drought-tolerant capacity, waste cooking oil (WCO) as an economic feedstock, and microalgae Chlorella vulgaris (MCV) which have high growth rate and productivity without farmland requirement, were produced by transesterification process with methanol and KOH catalyst. Physicochemical properties of these biodiesels were determined by GC-MS and FTIR analysis and evaluated with ASTM D6751 standard. FAME components profile illustrated the high value of oleic acid (C18:1) in ES and WCO and long-chain fatty acids (C18:2 and higher) in MCV. The engine tests results indicated that MCV biodiesel produced slightly lower power and higher BSFC compared with others. There was a slight increase in NOx for MCV biodiesel compared with pure diesel. Conversely, ES and WCO biodiesels had a reduction in NOx. On the other hand, MCV biodiesel resulted in the greatest reduction in CO and HC emissions. Based on the results, MCV blends had the lowest emissions and the best function among all feedstocks. • Comprehensive comparative analysis for considering three biodiesel generations. • Microalgae methyl ester contains the longest chain fatty acids among other feedstocks. • ES biodiesel had maximum calorific value and engine performance output. • MCV biodiesel resulted in the greatest reduction in HC, CO, and CO 2 emissions. • Contrary to ES and WCO, NOx emissions in MCV biodiesel were higher than pure diesel. [ABSTRACT FROM AUTHOR]