Effects of Waste Vegetable Oil/Water Emulsions on the Emissions of a Listeroid Diesel Engine

Abstract

This study presents the experimentally determined effects of filtered, heated, waste vegetable oil (WVO) and water emulsions on gaseous emissions, opacity, and fuel efficiency of a Listeroid diesel engine. Emissions studied are NOx, CO, CO2, SO2, O2, unburned hydrocarbons (UHCs), and opacity. WVO emulsions with water additions of 0%, 10%, 20%, 30%, and 40% by weight, heated to 95°C at injection are studied, and results are compared to diesel. The water addition limit was found to be between 41–49%, inclusive, at 50% load. Emulsions are maintained with a magnetic stirrer prior to entry into the fuel line. The WVO is preheated using heat from the exhaust gases. This reduces its viscosity prior to entering the fuel pump, reducing engine wear, pumping losses, and fuel starvation. The WVO is heated again to 95°C immediately before injection, using an externally powered heater to standardize test conditions. A new metric is introduced, namely, brake specific global warming potential (BSGWP). There is a significant reduction in BSGWP at 50% engine load and 30% water addition. Emissions from 40% water addition most closely resemble diesel engine emissions at all engine loads and are consistently lower than with pure WVO.

A comprehensive review on the application of emulsions as an alternative fuel for diesel engines

“…For a particular load, the increases of water percentage from 10% to 40%, with a step of 10%, have increased the HC emission almost linearly. However, preheating emulsified waste vegetable oil with 40% water by volume has been found to produce almost diesel equivalent HC emission, when run in a diesel engine [68]. Alongside, to achieve a lower HC, the IT of the water emulsified diesel fuel has also to be optimized (181BTDC) rather than just retarding (151BTDC and 121BTDC) or advancing it (211BTDC and 241BTDC).…”