Performance evaluation of waste fried vegetable oil in a medium grade low heat rejection diesel engine

Abstract

Investigations were carried out to evaluate the performance of a high grade Low Heat Rejection (LHR) diesel engine with ceramic coated cylinder head [ceramic coating of thickness 500 microns was done on inside portion of cylinder head] with different operating conditions [normal temperature and pre-heated temperature] of crude Waste Fried Vegetable Oil (WFVO) collected from restaurants, hotels etc., with varied injection pressure and injection timing. Performance parameters of brake thermal efficiency, exhaust gas temperature and volumetric efficiency were determined at various magnitudes of brake mean effective pressure (BMEP). Pollution levels of smoke and oxides of nitrogen (NOx) were recorded at the various values of BMEP. Combustion characteristics at peak load operation of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance with WFVO operation at recommended injection timing and pressure and the performance of both version of the engine was improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing was 32obTDC for CE while it was 29obTDC with LHR engine with vegetable oil operation. Peak brake thermal efficiency increased by 12.5%, volumetric efficiency decreased by 11%, smoke levels decreased by 10% and NOx levels increased by 32% with WFVO operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturer’s recommended injection timing of 27obTDC(Before top dead centre).