Fuel Deposit Characteristics at Low Velocity

An experimental program has been carried out to characterize the relationship between deposit mass, operating time, and temperature in studies of the thermal stability of aviation gas turbine fuel. This information is required by fuel system designers to prevent deposit buildup in fuel system components, thus allowing for more efficient designs. The program has included the design, fabrication, and operation of a novel thermal stability test apparatus for the determination of deposition rates over a range of temperatures and test durations up to several hundred hours. Experiments were run to determine the rate of deposit formation as a function of temperature in heated stainless steel tubes at low velocity using Jet A fuel. The test tube had an inside diameter of 0.22 cm, a length of 0.91 m, and a flow rate of 0.73 kg/h. Deposits obtained were often characterized as thick, porous, and nonuniform in nature. Deposit density based on carbon content was 0.08 g/cm³. Deposit rates of 0.1 to 100 μg C/h-cm² were observed at surface temperatures between 400 and 600 K.