Performance, Emissions and Combustion Characteristics of Waste Fried Vegetable Oil in Based Biodiesel in High Grade Low Heat Rejection Diesel Engine

Abstract

Experiments were conducted to evaluate the performance of a high grade low heat rejection (LHR) diesel engine with air gap insulated piston, air gap insulated liner and 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 waste fried vegetable oil based diesel (WFVOBD) with varied injection pressure and injection timing and compared the performance with one over the other and also with pure diesel operation on conventional engine (CE). Performance parameters of brake thermal efficiency, exhaust gas temperature and volumetric efficiency were determined at various values of brake mean effective pressure (BMEP). Exhaust emissions of smoke and oxides of nitrogen (NOx) were recorded at different 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. CE showed compatible performance, while LHR engine showed improved performance with waste fried vegetable oil in biodiesel form at recommended injection timing and pressure and the performance of both version of the engine improved with advanced injection timing and at higher injection pressure when compared with CE with pure diesel operation. The optimum injection timing was 33 o bTDC for CE while it is 32 o bTDC with LHR engine with biodiesel operation. Relatively, peak brake thermal efficiency increased by 18%, at peak load operation-brake specific energy consumption decreased by 6%, exhaust gas temperature decreased by 75 o C , volumetric effi- ciency decreased by 5%, coolant load decreased by 30%, sound intensity decreased by 35%, smoke levels decreased by 27% and NOx levels increased by 41% with biodiesel operation on LHR engine at its optimum injection timing, when compared with pure diesel operation on CE at manufacturer's recommended injection timing.