Optimization of NOx Emission from Soya Biodiesel Fuelled Diesel Engine using Cetane Improver (DTBP)

Within the depleting resources of fossil fuels and the increase in their price, in the recent past a lot of interest has been given to the use of plant oil specially the non-edible oil and its ester (biodiesel). Although the use of biodiesel in place of diesel has resulted in much lesser tail pipe emission, a substantial increase of NOx is reported by several researchers. It may be due to low cetane number and fuel radical’s formation during the combustion. Literature reported that mixing of an anti- NOx additive, such as di-tert-butyl peroxide (DTBP) in the bio-diesel before feeding to the nozzle, may reduce the NOx concentration in the CI engine emission. Considering this, a study was conducted on single cylinder four stroke diesel engines using blended soya methyl ester (B50) to optimize the NOx emission with the addition of DTBP cetane improver. The engine was first run on petroleum diesel (B0), followed by B50 and combination of B50 and DTBT. A number of combinations, 50% biodiesel (B50) and 50% petroleum diesel along with di-tert-butyl peroxide (DTBT) such as B50/D0.5, B50/D1.0, B50/D1.5, B50/D2.0, B50/D2.5 and B50/D3, were used in this study. For each test, engine performance and emission were measured. The addition of cetane improver could reduce the NOx emission significantly with the penalty of BSFC, CO and unburned hydrocarbon. The addition of DTBP by volumes of 0.5, 1, 1.5, 2, 2.5 and 3% to B50, the NOx reduction was found as 3.57, 5.0, 5.0, 4.29, 4.88 and 4.9%, respectively as compared to B50 without additive. It was also noted that CO and SOx reduce up to 25% and 33.33%, respectively, compared with petroleum diesel when 1% of DTBP is used. Considering the emission parameters, and the cost of the additive, 1% DTBP would give the optimum results for NOx reduction.