Effect of injection strategy and water content on water emulsion fuel engine for low pollutant compression ignition engines

Abstract

Diesel-water emulsion (DWE) is a low pollutant fuel technology that can be applied immediately to powertrain transition period. There are many previous studies on engine performance based on application of DWE; how-ever, studies on analyzing the effect of injection strategy are limited. Therefore, in this study, two types of DWEs with different water content manufactured in-house were applied to a conventional diesel engine. The effect of water content and injection timing was then analyzed and an optimal injection strategy was proposed. When the water content of DWE increased and injection timing was retarded, the nitrogen oxides (NOx) emission decreased. When the water content of DWE increased and injection timing was advanced, particulate matter (PM) emission decreased; however, when the water content was 20 wt% or more, PM emission was almost non-existent. Coefficient of variance of indicated mean effective pressure (CoVIMEP) was maintained below 2% even after increase in the water content and adjustment in injection timings under test conditions. PM emission is more influenced by water content of DWE than by injection timing. Therefore, to optimize pollutant emissions from DWE, delaying injection timing as much as possible is advantageous even if PM emissions increase slightly.