Title: Combustion and emission characteristics of a diesel engine fuelled with biodiesel having varying palmitic acid, stearic acid and oleic acid in their fuel composition

Authors: P. Tamilselvan; G. Nagarajan

Addresses: School of Mechanical and Building Sciences, VIT – Chennai Campus, Chennai-48, India ' Department of Mechanical Engineering, I.C. Engineering Division, Anna University, Chennai-25, India

Abstract: The present work discusses the performance and emission characteristics of blends of vegetable oil esters with varying saturated fatty acid composition tested on a stationary direct injection compression ignition engine. Saturated fatty acids are long-chain carboxylic acids that usually have between 8 and 24 carbon atoms and have no double bonds. The unsaturated fatty acids resemble saturated fatty acids, except that the chain has one or more double bonds. The biodiesels were derived from pongamia, coconut and palm oil respectively. The fuels were made from the biodiesels with saturated fatty acid composition as 57%, 62% and 75% respectively. The fuel composition has palmitic acid, stearic acid and oleic acid in varying proportions. The results show that the blends of biodiesel give low brake thermal efficiency. In emission analysis the blends give slightly higher oxides of nitrogen and lower carbon monoxide (CO) hydrocarbon (HC) and smoke emissions when compared to diesel. The fuel properties of the blends of vegetable oil esters show that the cetane number, density and viscosity are higher for the esters with high saturated fatty acid composition. The higher cetane number reduces ignition delay and also reduces NO_x emissions. [Received: March 20, 2013; Accepted: September 1, 2013]

Keywords: saturated fatty acid; brake thermal efficiency; combustion; heat release rate; biofuels; engine emissions; diesel engines; biodiesel; palmitic acid; stearic acid; oleic acid; vegetable oil esters; pongamia; coconut; palm oil.

DOI: 10.1504/IJOGCT.2014.065813

International Journal of Oil, Gas and Coal Technology, 2014 Vol.8 No.3, pp.353 - 368

Received: 22 Mar 2013
Accepted: 01 Sep 2013
Published online: 29 Nov 2014 *

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