Evaluation of esterified pyrolysis bio-oil as a diesel alternative

Abstract

Refined pyrolysis bio-oil was produced via the pretreatment and esterification of pyrolysis bio-oil over 732-type ion-exchange resin. The main parameters of fuel property such as components, low calorific value and viscosity of refined pyrolysis bio-oil were analyzed. Different volume fractions of refined pyrolysis bio-oil were added to neat diesel to prepare bio-fuel blends. Combustion performances and emission characteristics of engine fueled with bio-fuel blends were analyzed at various loads. The results show that after esterification, the amount of esters and ketones in the crude pyrolysis bio-oil was significantly increased while the contents of acids, phenols and ethers were reduced. Compared with crude pyrolysis bio-oil, the pH value of refined pyrolysis bio-oil was improved to 5.6, the low calorific value increased by 14.89%, and the kinematic viscosity decreased by 10.13%. At the same load, the equivalent brake specific fuel consumption (BSFC) of bio-fuel blends was increased, the maximum cylinder pressures and the brake thermal efficiency (BTE) were both decreased but the peak of instantaneous heat release was increased slightly, and the exhaust gas temperatures also rose up. With the increase of refined pyrolysis bio-oil in bio-fuel blends, the difference between bio-fuel blends and neat diesel in the above indicators was more obvious. Besides, bio-fuel blends produced more HC, CO and smoke emissions but less NOx emissions than neat diesel.