DOI: 10.5176/2251-189X_SEES15.26

Authors: Rajnish Kaur Calay and Claudia Pisac

Abstract:

Comparative analysis of combustion performance and exhaust emissions from the combustion of biodiesel made from waste cooking oil (WCO) and petroleum diesel is presented in this paper. To combat with the issues relating to energy deficit and environmental pollution due increasing demand and depleting fossil fuels, alternative fuels are explored that can substitute petroleum fuels, particularly for the transport sector. In this regard, waste cooking oil makes a good candidate for alternative transport fuel. Biodiesel from WCO is already being used in certain ratios in the US, EU and other countries. There are still some issues relating to running diesel engines on WCO due to differences in the chemical composition between biodiesel and diesel. Therefore, more information of the overall performance in engines and emission formation is desirable. Experimental tests were conducted using Land Rover VM diesel engine. Elemental analysis of WCO biodiesel showed that there are differences between the functional groups in diesel and biodiesel which lead to major differences in the combustion characteristics of the two fuel types. It was found that biodiesel had 10{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} lower carbon content, almost no Sulphur content and up to 12{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} more oxygen content compared with diesel. Higher oxygen content and double bounds in WCO biodiesel increase its susceptibility to oxidation. Higher Oxygen content explains the lower caloric value for WCO biodiesel (up to l8 {6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}) compared with diesel. This was evident in decrease in engine torque with up to 9{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} for biodiesel compared with that of diesel. Using WCO blends ratio up to 75{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} in diesel showed a reduction in exhaust emissions compared with diesel, nevertheless, at the cost of increased fuel consumption. The brake specific fuel consumption (BSFC) increases as the biodiesel blend ratio in diesel increases due to greater mass of fuel being injected at a given injection pressure, compared with diesel. A common conclusion can be drawn in favor of the WCO biodiesel as being a greener alternative to petro-diesel when used in blend with diesel. Large variations in the feedstock used for biodiesel production would lead to variations in the physical and chemical properties of the WCO biodiesel produced. Stringent standards may need to be imposed for biodiesel quality in order to reduce the effect of variation in physiochemical properties on engine performance and emissions. Nevertheless, tests confirmed that biodiesel-diesel blends can be used in current diesel engines without loss of performance.

Keywords: Biodiesel, Waste cooking oil (WCO), Combustion, Emissions

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