Engine performance and emissions evaluation of surfactant-free B30 biodiesel–diesel/water emulsion as alternative fuel

Abstract Malaysia is one of the top exporters of palm oil, and although currently facing fierce resistance towards palm oil imports in some parts of the globe, one of the ways to utilize this commodity is by increasing palm biodiesel content in local commercial diesel. However, due to the oxygen-rich nature of biodiesel, its utilization suffers from increased nitrogen oxides (NOx) emission compared to conventional diesel. To mitigate this issue and improve diesel engine performance and emissions using biodiesel–diesel blends, this study attempted to investigate implementation of a real-time non-surfactant emulsion fuel supply system (RTES) which produces water-in-diesel emulsion as fuel without surfactants. NOx reducing capability of water-in-diesel produced by RTES has been well documented. Therefore, in this study, 30% biodiesel–diesel (B30) was used as the base fuel while B30-derived emulsions consisting of 10 wt%, 15 wt% and 20 wt% water content were supplied into a 100 kVA, 5.9-L common rail turbocharged diesel engine electric generator. Fuel consumption and exhaust emissions were measured and compared with commercially available Malaysian low grade diesel fuel (D2M). Evidence suggested that emulsified B30 biodiesel–diesel produced by RTES was able to increase brake thermal efficiency (BTE) up to a maximum of 36% and reduce brake specific fuel consumption (BSFC) up to 8.70%. Furthermore, B30 biodiesel–diesel emulsions produced significantly less NOx, carbon monoxide and smoke at high engine load. In conclusion, B30 biodiesel–diesel emulsions can be readily utilized in current diesel engines without compromising on performance and emissions