The vast stores of biomass available worldwide have the potential to displace significant amounts of petroleum fuels. Fast pyrolysis of biomass is one of several possible paths by which we can convert biomass to higher value products. Pyrolysis oil (PO) derived from wood has been regarded as an alternative fuel to be used in diesel engines. However, the use of PO in a diesel engine requires engine modifications due to the low energy density, high acidity, high viscosity, and low cetane number of PO. Therefore, PO should be blended or emulsified with other fuels that have a high cetane number or used through pilot injection.
PO has poor miscibility with light petroleum fuel oils; the most suitable candidate fuels for direct fuel mixing are alcohol fuels. Early mixing with alcohol fuels has the added benefit of significantly improving the storage and handling properties of the PO. For separate injection co-firing, a PO-ethanol blend can be fired through diesel or biodiesel pilot injection in a dual-injection diesel engine. In this study, the performance and emission characteristics of a dual-injection diesel engine fueled with diesel & biodiesel (pilot injection) and PO-ethanol blend (main injection) were experimentally investigated. Results showed that although stable engine operation was possible with dual injection, the fuel conversion efficiency was slightly decreased compared to that of diesel and biodiesel combustion. Regarding the exhaust emissions, THC & CO emissions were slightly increased and NOx & soot emissions were significantly decreased due to the high water content and oxygen content in the PO-ethanol blend.
