Effect of different size cerium oxide nanoparticles on performance and emission characteristics of variable compression ratio engine fuelled with diesel-palm biodiesel blends

Abstract

An experimental investigation was carried out to evaluate performance and emission characteristics of direct injection, single cylinder, water cooled variable compression ratio diesel engine using cerium oxide nanoadditive of two different particle size dispersed in diesel and palm Biodiesel blends B10 and B20. In first part of experiment CERIA21( cerium oxide of particle diameter in the range of 21-30nm) and CERIA41( cerium oxide of particle diameter in the range of 41-50nm) are blended with diesel and palm biodiesel blends B10 and B20 in dosage of 150 ppm using ultrasonic bath stabilizer at 15 min sonication time. The stability characteristic of prepared fuel blends with CeO2 was find out, The results of which revealed that CERIA21 blended fuel has high stability and less percentage transmittance compared to CERIA41 blended fuels, this is due to better suspension of fuel and less agglomeration for smaller particles. Whole
experiment was carried out using following fuels: neat diesel, B10, B20, B10+CERIA21, B10+CERIA41, B20+CERIA21, B20+CERIA41. The experimental results showed that as biodiesel concentration increased BSFC and brake thermal efficiency decreases. Addition of CeO2 in base fuel improves BTE and reduce BSFC owing to its high surface area to volume ratio, thermal conductivity and oxidation stability. At full load BTE was improved by 3.62%, 2.95%, 3.20% and 2.43% with B10+CERIA21, B10+CERIA41, B20+CERIA21, B20+CERIA41 respectively at higher CR. Highest BTE and lowest BSFC was observed with B10+CERIA21 at 24.68% and 0.3204 kg/kw.hr at full load and
CR16.5. At lower CR fuel injected in colder combustion chamber which provides insufficient heat for compression which ultimately increase BSFC and reduce BTE. Carbon monoxide(CO) and hydrocarbon(HC) emission were reduce with B10 and B20 due to higher oxygen content than diesel, addition of CeO2 further reduces these pollutants. with B10+CERIA21, B10+CERIA41, B20+CERIA21 and B20+CERIA41 CO emission reduced by 38.88%, 22.22%, 56.25% and 37.5% at CR 16.5 whereas HC reduced by 11.76%, 8.25%, 12.65% and 8.86% respectively. NOx increases with B10 and B20 compared to diesel due to high cylinder temperature, CeO2 addition further increases NOx emissions. Highest NOx observed with B20+CERIA41 as 744 ppm. Overall performance with CERIA21 was better than CERIA41.