As a way to improve the combustion characteristics of wood tar which is highly viscous and flame retardant, the authors blended it with liquefied dimethyl ether (DME), which can improve fuel fluidity, ignitability and spray atomization. Moreover, heavy fuel oil (bunker-c oil) was added to increase the heating value of this fuel sample. The sample, which has the blending ratio of 35 % wood tar, 30% DME and 35% bunker-c by weight, was used in a combustion test with a three-cylinder in-direct injection diesel engine. Additionally, the authors also investigated particulate matter (PM) produced after burning four samples that mixed liquefied DME with flame retardant fuels in the same engine to analyze its environmental and biological impacts. The four samples prepared for the experiment were (1) 70% distillate oil (bunker-a) and 30% DME; (2) 85% bunker-c and 15% DME; (3) 70% bunker-c and 30% DME; (4) 35 % bunker-c, 30% DME and 35% wood tar.
The results of the engine test suggested the possibility that wood tar could become more combustible by optimizing the flow rate of fuel and the blend ratio of liquefied DME and bunker-c. In the (4) case, PM showed no high mutagenic potentials and there were lower concentrations of such inorganic substances as vanadium and nickel. Polycyclic aromatic hydrocarbons (PAHs) concentrations in PM decreased by blending liquefied DME with bunker-c, whereas did not decrease for the wood tar.
