How does 8 pounds of fuel convert to 22 pounds of CO2?
When the diesel fuel is burned, the two oxygen atoms of the carbon dioxide produced come from the air, as well as another oxygen atom that combines with two hydrogen atoms in the hydrocarbon fuel to produce water vapor. (There are some other minor byproducts such as CO, nitrogen compounds, and soot.)
Each carbon atom in the fuel gets attached to either one or two oxygen molecules, creating CO and CO2. Apparently as a result of the combustion conditions in a diesel engine CO2 is produced at about 100 times the rate of carbon monoxide.
Add O2 from the air.