Use of Hydrogen Peroxide to Improve the Performance and Reduce Emissions of a CI Engine Fuelled with Water Diesel Emulsions

Use of water diesel emulsions in diesel engines reduces simultaneously smoke and NOx emissions. However the ignition delay increases and there is a rise in the HC and CO levels as well. In this work hydrogen peroxide was added to water diesel emulsion and tested in a diesel engine. Initially the engine was run with water diesel emulsion (water to diesel ratio of 0.4:1). The water diesel emulsion with a H₂O₂/diesel ratio of 0.05 was used. The single cylinder diesel engine was tested at the rated speed of 1500 rpm. Brake thermal efficiency increased with hydrogen peroxide from 32.6% to 33.5% as compared to the plain emulsion at full load. These values are even better than neat diesel operation. CO and HC levels decreased significantly with the addition of H₂O₂. HC with the neat diesel engine at full load was 50 ppm. It rose to 75 ppm with water diesel emulsion and was controlled to 50 ppm when H₂O₂ was used. This is due to the strong oxidizing nature of H₂O₂. NO emission decreased slightly with hydrogen peroxide addition as compared to neat water diesel emulsion due to a reduction in ignition delay. Smoke emission also decreased due to better oxidation of the fuel. It is demonstrated through this study that even a small quantity of H₂O₂ can lead to a significant improvement in overall performance of the engine with water diesel emulsions. However, the long term effects have to be assessed.