Investigation Of Corrosive Wear Behaviours Of Biomass Fuel

As a green and renewable energy, the biomass-fuel has been considered as one of potential engine fuels. The biomass-fuel may have an influence on the lubrication property between piston ring-cylinder liner and lead to the corrosive wear because of its typical organic compounds with acids. At the same time, it may cause the cavitation corrosive wear of pump blade, pipe and nozzle of engine during the transport, spray and atomization of fuel. It may also have an influence on the stable working and safe performance of engine, and it is necessary to study the corrosive wear and mechanism of biomass fuel.The original biomass-fuel and modified biomass-fuel were selected to investigate their tribological behaviours and mechanism of corrosive wear by way of a reciprocating tribometer in this thesis. The caviattaion-induced corrosive wear of the engine nozzle material was also studied by using a magnetostrictive-induced cavitation vibratory apparatus. It can provide the guidance for the application of high-grade biomass-fuel in the diesel engine.1. The basic physical and chemical properties of the original biomass-fuel and refined biomass-fuel (biomass-fuel/diesel blend by emulsion) were tested according to the national standards for the test method of petroleum and petrochemicals. Their test results were compared with the reference of0#diesel fuel. The color or basic physical and chemical properties of the original biomass-fuel were worse than those of0#diesel. The quality of biomass-fuel after modification by the emulsification process was close to that of0#diesel. Compared with the original biomass-fuel, the refined biomass-fuel was improved greatly in the color and transparency.2. Using0#diesel as a reference, it was investigated the corrosive wear of the original biomass-fuel with reciprocating sliding with a variable movement frequency. The results showed that the friction coefficients of biomass-fuel and their wear weight losses increased with the increase of the reciprocating frequency (frictional velocity) when the load was kept constant. Compared with0#diesel fuel, its antifriction was better than that of0#diesel. However, its wear resistance was worse than that of0#diesel. In addition, the corrosive wear of the original biomass-fuel was also studied under variable loads and compared with that of0#diesel under the same conditions. The results showed that the friction coefficients of biomass-fuel decreased with the increase of load. The wear weight loss increased also with the increase of load when the reciprocating frequency was kept constant. The friction coefficient of biomass-fuel was lower than that of0#diesel, but its wear weight loss was higher than that of0#diesel under the same frictional conditions.3. Compared with0#diesel, the corrosive wear behaviours of three different ratios of emulsified biomass-fuel were evluated with reciprocating sliding tribometer. The result showed that the friction coefficient of emulsified biomass-fuel and its wear weight loss increased with the content of biomass-fuel in the blend. The friction coefficient of blend with5wt%biomass-fuel was lower than that of0#diesel, and its wear weight loss had little difference with that of0#diesel. Therefore, the blend with5wt%biomass-fuel was selected to explorer the corrosive wear under different frictional conditions. The results showed that the friction coefficient and wear weight loss increased with the reciprocating sliding frequency when the load was constant. The friction coefficient and wear weight loss increased with the load when the reciprocating sliding frequency was constant. At last, it was studied that the effect of the blend fuel with5wt%biomass-fuel on the tribological properties of commercial engine lubricating oil SAE CD15W/40. The result showed that the friction coefficient and the wear weight losses of frictional couples increased with the blend content in the lubricating oil.4. It was studied the cavitation-induced the corrosive wear of the blend fuel with5wt%biomass-fuel. Using magnetostrictive-induced cavitation vibratory apparatus to simulate the cavitation conditions generated by engine nozzle, it was studied that the effect of the temperature of the blend fuel with5wt%biomass-fuel on the corrosive wear of nozzle material (GCr15). The results showed that viscosity and surface tension of fuel was declined with the increase of temperature of emulsified biomass fuel, the cumulative mass loss rate of nozzle material first increased and then decreased because of the variation of microjet impact. The viscosity and surface tension of fuel would cause the biggest impact from the microjet when the fuel temperature was at45℃, the cumulative mass loss and the cumulative mass loss rate of nozzle material reached their highest values respectively.