Application of biomass fast pyrolysis part II: The effects that bio-pyrolysis oil has on the performance of diesel engines

This study used the fast pyrolysis method to produce bio-oil from coffee bean residue. The oil was mixed with diesel fuel through emulsification to produce emulsified fuel with varying proportions. A single-cylinder diesel engine connected to a 12-kW power generation system was used as the test system to examine the performance indices of a diesel engine under various loads and rotational speeds when using three fuel mixtures with varying proportions of bio-oil (i.e., CPO (coffee bean residue pyrolysis oil) 0 (100% diesel), CPO 5 (5 vol.% bio-oil/95 vol.% diesel), and CPO 10 (10 vol.% bio-oil/90 vol.% diesel)). According to the results, compared to CPO 0, the addition of CPO 5 and CPO 10 increased the fuel consumed for the same power output. Although CPO 5 and CPO 10 had lower heating values that reduced combustion efficiency, the water content and emulsification properties of these fuels enhanced certain aspects of combustion. Increasing the proportion of bio-oil effectively reduced NOx emissions, but in certain situations, denser smoke was produced. The smoke resulted from the added bio-oil, which reduced heating values and combustion efficiency. The emulsification properties of the oil contributed to microexplosion of oil droplets, which enhanced combustion characteristics.