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

Investigations were carried out to evaluate the performance of direct injectiondiesel engine with medium grade low heat rejection (LHR) combustionchamber and 3 mm air gap insulated piston, 3 mm air gap insulated liner, andceramic coated cylinder head [ceramic coating with the thickness of 500 μ wasmade on the inside portion of the cylinder head].The engine had differentoperating conditions [normal temperature and pre–heated temperature] of crudewaste fried vegetable oil (WFVO) which was collected from restaurants, hotels,etc. with varied injector opening pressure and injection timing. Performanceparameters and exhaust emissions were evaluated at various values of brakemean effective pressure of the engine, while combustion parameters weredetermined at full load operation of the engine using special pressure–crankangle software package. Comparative studies were performed betweenvegetable oil operation and diesel operation in the engine with both versions ofthe combustion chamber with varied injection timing and injector openingpressure. Conventional engine (CE) showed deteriorated performance, whilethe engine with medium grade LHR combustion chamber had improvedperformance with waste fried vegetable oil operation at the recommendedinjection timing and pressure. Performance of both versions of the combustionchamber improved with advanced injection timing and at higher injectoropening pressure compared with CE with pure diesel operation. The optimuminjection timing was 32o bTDC (before top dead centre) with conventionalengine, while it was 30o bTDC for the engine with LHR combustion chamberand vegetable oil operation. Compared with pure diesel operation in theconventional engine, at manufacturer s recommended injection timing of 27obTDC, peak brake thermal efficiency increased by 9% at full load operation,brake specific energy consumption decreased by 2%, volumetric efficiencydecreased by 13%, smoke levels decreased by 10%, and nitrogen oxide (NOx)levels increased by 44% with waste fried vegetable oil operation in the enginewith LHR combustion chamber.

کلیدواژه ها:

Vegetable oil ، LHR ، Combustion chamber ، Fuel ، Performance ، Exhaust emissions ، Combustion characteristics