The study of the flame characteristics and emissions of oxy fuel combustion of diesel and diesel bio‌diesel blends is performed using an experimental test burner manufactured for this reason in a laboratory
scale. The fuels used are the conventional diesel fuel and a mixture of diesel and bio-diesel (B0, B10,
B20, and B40) when the number refers to the bio-diesel percentage in the blend, In this present paper the
behavior change of CO, CO2, HC, and NOx emissions was investigated for the selected blends with the
increasing of oxygen concentration gradually by an oxygen cylinder to the air consumed in combustion.
The flame characteristics (cone angle, flame length and appearance) also studied with the oxygen
concentration change. It was observed that the carbon monoxide, carbon dioxide, unburned
hydrocarbons, NOx, and the temperature are higher in diesel than bio-diesel blends in air combustion and
in oxy- combustion. This may because the number of hydrogen and carbon atoms is more in conventional
diesel than bio-diesel, also the calorific value, so the temperature is higher. The flame cone angle and
flame penetration length decreased after the addition of oxygen and bio-diesel, this is due to the presence
of sufficient amount of oxygen which causes early chemical reaction between the fuel and oxidizer. By
using oxy fuel combustion of renewable sources we can save money spent in conventional petroleum
fuel.