Investigation of the effect of carbon nanotube addition to diesel-biodiesel blend on engine performance and exhaust emissions

Increasing concerns caused by environmental pollution have promoted the use of cleaner and renewable fuels in internal combustion engines. Biodiesel is used as an alternative fuel in diesel engines in many countries. However, compared to diesel fuel, the high viscosity of the biodiesel and consequently the poorer atomization characteristic causes its use to be limited. In order to improve these properties of biodiesel, researches have been conducted on the use of various additives. In this study, the effects of carbon nanotube additive on performance and emission characteristics of a single cylinder direct injection diesel engine powered by biodiesel-diesel fuel were investigated. In experiments carried out at full load depending on engine speed, thermal efficiency, engine power and torque and exhaust emissions were examined. The in-cylinder pressure and heat release rate were also analysed at the maximum torque speed. It was determined that the carbon nanotube additive advanced the start of combustion and improved thermal efficiency. Maximum thermal efficiency was achieved as 39.3% when 100 ppm carbon nanotube additive was used. It was also found that the carbon nanotube additive reduced CO, HC and soot emissions, but increased NOx emissions due to improved engine performance. It was determined that 100 ppm carbon nanotube additive increased NOx emissions by approximately 11%, whereas CO, HC and soot emissions decreased by 20%, 26% and 7.9%.