Effect of heavy oil viscosity on combustion heat.

Calorific value is an important economic indicator of fuel. Usually, the low calorific value of oil is 38.5~44MJ/kg. Generally speaking, the heavier the oil, the smaller the relative hydrogen content and the lower the calorific value. The calorific value of heavy oil is lower than that of gasoline, generally between 40 and 42 MJ/kg. The overall requirements for fuel selection should be moderate viscosity, good combustion performance, high calorific value, good atomization performance, complete combustion, less carbon deposits and ash, low corrosion to burner parts, and easy storage, transportation, and pressurization. Heavy oil is generally prepared from cracked heavy oil, vacuum heavy oil, atmospheric heavy oil or wax oil in different proportions. Compared with straight-run (reduced pressure, normal pressure) heavy oil, cracked heavy oil has a larger viscosity and relative density, and contains larger solid impurities. They are easy to precipitate, block pipelines and fuel preheaters, and are not easy to burn. Therefore, the smaller the proportion of cracked heavy oil in the selected heavy oil, the better.

The same type of oil has different viscosities at different temperatures. High viscosity is not conducive to atomization. Poor atomization reduces combustion efficiency. What appears on the surface is that the output is small. The calorific value (heat value) of the same type of oil is fixed. So, should your question exactly be titled: What is the effect of heavy oil viscosity on combustion efficiency?

you're right. Thanks to the above two for their help.