Effect of Adding Hexagonal Boron Nitride (hBN) Nano-Powder to Lubricant on Performance and Emissions in a Two-Stroke Gasoline Engine

The two-stroke engine has many advantages, including low maintenance costs, a high specific power, and a simple structure, compared to four-stroke engines. Since two-stroke engines use a fuel–oil mixture instead of fuel alone, two-stroke engines do not need an oil pan. Unlike the lubrication system in four-stroke engines, the moving parts are lubricated with a fuel–lubricant mixture. As long as the engine is running, the fuel and lubricant burn together. The combustion of this fuel–lubricant mixture can adversely affect exhaust emissions and cause excessive carbon deposits on the spark plug. In this paper, experiments were carried out using different amounts of oil (100:3, 100:3.5, and 100:4 vol.) in a two-stroke gasoline-powered generator. In addition, we attempted to improve the lubricant’s properties by adding hBN (0.5% vol. or 1.3% wt.) to the lubricant. It was observed that the flash point and pour point did not change as a result of the addition of hBN to the lubricant, and the density and viscosity index increased linearly depending on the amount of hBN. In a series of experiments, the generator was examined for performance and emissions. With the addition of hBN, there was a significant decrease in the specific fuel consumption and exhaust gas temperature, the CO 2 increased, and the CO and HC decreased. These results show that hBN improves combustion. As a result, it was reported that reducing the amount of lubricant leads to increased emissions and decreased performance. It was found that when 0.5% hBN by volume is added to the lubricant, the lubricating property improves, and thus, the amount of oil added to the fuel can be reduced to an acceptable level (from 100:4 to 100:3.5) without causing mechanical failure in the engine.