Engine characteristics study on beef tallow biodiesel produced by ethanol based co-solvent transesterification

Abstract

ABSTRACT This present study looks at the engine characteristics of beef tallow biodiesel (tallow methyl ethyl ester) produced using methanol–ethanol-based co-solvent transesterification. Unblended samples of tallow methyl ethyl ester (TMEE), tallow methyl ester (TME) and tallow ethyl ester (TEE) were tested for their performance; combustion and emission characteristics in CI engine with ordinary diesel as reference fuel. From combustion characteristics, TMEE reported increased mean peak in-cylinder pressure (5.992 ± 1.34 MPa) and heat release rate (HRR) (61.52 ± 1.28 kJ/m3.deg) than TME on account of its higher cetane number and fuel bound oxygen content; however, TEE exhibited increased mean in-cylinder pressure (1.75%) and HRR (2.14%) than TMEE sample. Likewise, TEE exhibited superior fuel consumption (SFC) rate (on average, 2.67%) and brake thermal efficiency (BTE)(on average, 3.53%) than TMEE; while, TMEE displayed reduced SFC (on average, 11.43%) and increased BTE (on average, 12.46%) than TME in view of its increased calorific value contributed by TEEs in it. Besides, emission characteristics reported reduced CO emission level and exhaust HC concentrations (on average, 10% and 7.1%, respectively); along with slightly increased CO2 and NOX emissions (on average, 4.79% and 5.82%, respectively), in case of TMEE when compared to TME. Here, reduced emission characteristics of TEE, followed by TMEE were because of their high oxygen content and increased cetane number contributed by the ethyl esters available in them; which also signified the completeness of their combustion.