Search Results

Transesterified fuels (biodiesel fuels; BDF) from vegetable oils are alternative fuels for diesel engines, they are renewable and offer potential reductions in carbon dioxide emissions. Many studies have reported that exhaust from BDF has equal or higher NOx concentrations while HC and PM emissions are significantly lower than with gas oil. The aim of the present investigation is to achieve drastic reductions in NOx emissions. Performance tests of a single cylinder DI diesel engine were conducted using water emulsified fuels from BDF and gas oil with varying water addition rates combined with cooled EGR. The result showed that at a rated output, the emulsified gas oil with water to base fuel volume ratio of 30% reduced NOx (from 1020ppm) to 190ppm with the 21% EGR condition maintaining the minimum BSEC value achieved with EGR free gas oil operation. However, the smoke density increased by 28%.

This paper investigates engine performance with a stable emulsified fuel including frying oil, composed of vegetable oils discarded from restaurants and households. To reduce the oil viscosity, equal proportions of used frying oil and gas oil were mixed and emulsions of this blended fuel and water were prepared. Performance tests of a single cylinder DI diesel engine showed that the Nox concentration and smoke density both reduced without worsening BSFC with water to fuel volume ratios of 15∼30% at a rated output. The engine was also operated with transesterified fuel from used frying oil, the so called “biodiesel”. The BSFC of neat biodiesel was lower than with gas oil at high loads and retarded injection timings, while the smoke density was reduced at all operating conditions.