Utilization of biomass-derived pyro-oils in compression ignition (CI) engines – recent developments

Abstract

Recent developments in different aspects of pyrolysis technology such as input energy and waste feedstocks were discussed in the study. Insights into the utilization of pyro-oils in compression ignition (CI) engines were highlighted along with the engine behavior assessment. Performance (thermal efficiency), combustion (in-cylinder pressure rise and heat release rate), and emission (hydrocarbons (HC), carbon monoxide (CO), smoke, and oxides of nitrogen) behaviors of CI engines, fueled with pyro-oils, were compared with conventional base diesel operation. Most of the literature supported a slight reduction in the thermal efficiency of the engine with the employment of pyro-oils due to lower calorific value. Combustion behavior of pyro-oil-fueled engines is almost comparable with conventional diesel operation. All carbon-derived emissions such as HC, CO, and smoke decreased with the use of pyro-oils in engines. However, some investigations reported fluctuating trends for the emissions. Overall, it may be concluded based on the comparative analysis of engine behavior that pyro-oils derived from different biomass feedstocks could be used for engine application with comparable performance and emission behaviors. However, the significant challenges related to char removal from biomass-derived pyro-oils and engine’s fuel line system need to be resolved for effective employment of pyro-oils in engine applications.