Experimental investigation of engine performance, emission and combustion characteristics of tea tree oil blend in a CI engine

Essential oils are mainly used in the aromatherapy and natural medicine sector. However, as high quality oils are needed in this sector, there is a significant essential oil waste-stream which can be used in transport and agricultural sector specially in diesel engines. The aim of this paper is to evaluate a multi-cylinder diesel engine using tea tree oil (TTO) essential oil blended with diesel. The blend contained 90% diesel and 10% TTO (by volume). The diesel engine used was a 160kw modern high speed common rail turbocharged diesel engine. The engine was operated at 1500 rpm and 4 loads. Property-wise, compared to base diesel, TTO-diesel blend has lower viscosity, higher density significantly lower heating value and cetane number. There was minimal variation of brake thermal efficiency and brake specific fuel consumption between base diesel and TTO-diesel blend. However, in-cylinder pressure for TTO-diesel blend was significantly lower compared to base diesel. In most loads, TTO-diesel blend emitted lower NOX but significantly higher CO and PM emission.