What does an increase in the oil's specific gravity generally indicate regarding its burning characteristics?

An increase in an oil's specific gravity generally indicates a lower hydrogen content. Specific gravity is a measure of the density of a substance compared to the density of water. In the context of fuels, oils with higher specific gravities tend to have a higher proportion of heavier hydrocarbons and a lower composition of lighter hydrocarbons, which contain more hydrogen.

Hydrogen content is crucial in determining burning characteristics; fuels with higher hydrogen content typically burn more readily and release more energy upon combustion. Therefore, as specific gravity increases and hydrogen content decreases, the fuel becomes less efficient in terms of energy release when burned.

This relationship helps in assessing the combustion characteristics of different types of oils, especially in power engineering applications where the energy output and efficiency of fuels are critical for various processes and systems.