Combined influence of compression ratio and exhaust gas recirculation on the diverse characteristics of the diesel engine fueled with novel palmyra biodiesel blend
Geddam Prasada Rao, L. S. V. Prasad
Abstract
The current study investigates the influence of compression ratio and EGR on the various characteristics of diesel engine operated with 20% Palmyra oil methyl ester (POME 20) blend at different load conditions. Transesterification process is used to produce the palmyra oil methyl ester from the palmyra crude oil, which is extracted from the palmyra seeds by the application of mechanical pressing operation. ASTM standards have been used to determine the physico-chemical characteristics of palmyra oil methyl ester and these properties are close competing with the diesel fuel. Preliminary tests are conducted with blends of palmyra oil methyl ester (POME 10, POME 20 and POME 30) on diesel engine working at standard conditions and it is found improved engine performance and reduced emissions for POME20. One of the viable techniques to enhance the engine characteristics is to change the operating parameters. In this context, the present work focuses on the influences of distinct compression ratios (16:1, 18:1 and 20:1) on the diverse characteristics of diesel engine fuelled with POME 20 blend. The experimental test findings indicate that the brake thermal efficiency is enhanced by 6.91% and BSFC is lowered by 10.2%; and considerable decreases in carbon monoxide, unburned hydrocarbons, and smoke opacity emissions by 13.33%, 8.82% and 8.2% respectively found at compression ratio 20:1 when compared to POME 20 operated at compression ratio 16:1. However, the NOx emissions are found to be higher. EGR is the simplest, cheapest and most effective technique used for reduction of NOx emissions for diesel and biodiesel fuelled diesel engine. In this, EGR is added 5% and 10% rates to the POME 20 operated at 20:1 compression ratio. The test results revealed that the addition of 10% EGR to the POME 20 is found 23% reduction of NOX emissions when compared to POME 20 operated at standard operating conditions.