Experimental Comparison of Fuel Scrubbing Inerting Process Using Nitrogen and Carbon Dioxide of Aircraft Fuel Tanks

Fuel scrubbing technology could be used for fuel tank inerting and fuel deoxygenation. Both N₂ and CO₂ are perfect inert gases, but the solubility of CO₂ is nearly 20 times higher than that of N₂ in jet fuels, so the scrubbing inerting process varies with the selection of N₂ or CO₂. A scrubbing test bench is constructed, and the variation of oxygen concentration on ullage or in the fuel is measured under various flow rates, fuel loads and initial oxygen concentrations on ullage. Experimental results reveal that the ullage and dissolved oxygen concentrations of CO₂ scrubbing are always higher than that of N₂ scrubbing. The inerting time of CO₂ scrubbing of a 30%, 50% and 70% fuel load is approximately 1.42, 1.7 and 2.75 times that of N₂ scrubbing, respectively. The scrubbing test under 5%, 9% and 14% initial ullage oxygen concentration revels a peak in ullage oxygen concentration of 7.23% and 9.97% for N₂ scrubbing and that of 12.63%, 13.4% and 15.4% for CO₂ scrubbing, respectively.