Performance and Emission Studies on a CI Engine Using Methyl Esters of Palm Oil and Waste Cooking Oil Mixture as Fuel

Abstract

Palm oil (PO) is considered as one of the promising feed stocks for bio-diesel production due to its low cost and good production output. However, it is in solid form at ambient temperature. Mixing PO with waste-cooking oil (WCO) helps to reduce viscosity of PO significantly. This has the potential to reduce disposal of waste cooking oil. Making esterified fuel from this mixture of PO + WCO can be an effective method of preparing bio-diesel from waste which can be used as fuel in diesel engines. In this work refined palm oil was used as main fuel for preparing the methyl ester. Waste cooking oil was used as an inter esterification agent to reduce overall viscosity and cloud point of the blend and the ester. A single cylinder, direct injection, air cooled diesel engine was tested using neat diesel, neat PO and the methyl ester of the mixture (PO +WCO) as fuels under variable load operating conditions. Results showed increased specific fuel consumption with neat PO and methyl esters of PO+WCO mixture as compared to neat diesel. Specific hydrocarbon and carbon monoxide emissions were significantly reduced with the methyl esters of PO+WCO mixture as compared to neat PO. The specific hydrocarbon emission was found as 2 g/kW.hr. with the methyl esters of the mixture of PO+WCO and 5.2 g/kW.hr with neat PO at the maximum power output. Whereas it was 3.8 g/kW.hr. with neat diesel. The reduction in HC and CO emissions with the methyl esters of the mixture of PO+WCO was due to the better combustion of the ester as compared to neat PO. NO and NOx emissions were found higher with the methyl ester of PO+WCO as compared to neat PO due to increased cycle temperature as a result of improved combustion rate. On the whole it is concluded that methyl esters of the mixture of PO+WCO can be used as fuel in diesel engines without modification in engine design.