Investigation on the long-term effects of plastic pyrolysis oil usage in a diesel engine

This paper presents the long-term effects of plastic pyrolysis oil (PPO) in a diesel engine when it is used as a primary fuel. Our previous investigation indicated that PPO is a promising fuel; however, the results suggested that the addition of diesel is necessary in order to obtain acceptable engine performance. In the present work, a blend of 75% PPO and 25% diesel was utilized in the engine for the longevity test. The engine failed after 36 hours on PPO blend when a piston was cracked. The engine's combustion, performance and emissions characteristics were monitored throughout the longevity test revealing that the engine performance deteriorated dramatically the last hours of operation. Moreover, the analysis of the exhaust temperatures during the failure moment suggested that the underpinning reason for the cracked piston was the injector failure. After the failure, the engine was opened and the engine's parts were investigated showing excessive wear. The lubricant oil was analysed and confirmed the increased wear due to the elevated contamination. Finally, the deposits from the piston heads were collected and analysed revealing that incomplete combustion was taking place.