Influence of WPO (Waste Plastic Oil) - gasoline mixtures for emission characteristics on working spark-ignition engine

The utilization of liquid products as transportation fuel derived from the thermal decomposition of different plastic waste mixtures was investigated. The production of pyrolysis oils was performed in a laboratory-scale batch reactor utilizing polystyrene (PS), polypropylene (PP), and high-density polyethylene (HDPE) waste blends. Two different mixtures (10% PS – 60% PP – 30% HDPE; 10% PS – 30% PP – 60% HDPE) were prepared, and the influence of reflux was also studied. The pyrolysis oils were blended to commercial gasoline in the 0-100% range. It was found that each blend could be successfully used as an alternative fuel in a traditional spark-ignition engine without any prior modifications or fuel additive. However, based on the engine tests, the presence of the reflux is vital as the composition of the pyrolysis oil is closer to the commercial gasoline. The emission measurements showed increasing NOx emissions compared to neat gasoline, but, on the other side, a decrease in CO was noticed. These changes were much smaller in cases when reflux was used during oil production. Based on the obtained results, the utilization of reflux-cooling is an effective method to enhance the gasoline range hydrocarbons in the plastic waste pyrolysis oils, and therefore blending these oils to commercial gasoline might be viable.