Dynamic behaviors of coking process during pyrolysis of China aviation kerosene RP-3

• RP-3 as an endothermic fuel was studied at temperatures up to 640 °C.
• Coking process was a combined result of a deposition process and a removal process.
• Coking process was an unsteady and dynamic one with randomness.
• Random coke buildup and removal may occur in a short time.
• Surface deposition enhanced the heat transfer at the test conditions.

China aviation kerosene RP-3 was used as an endothermic fuel to pyrolyze in an electrically heated horizontal channel with an internal diameter of 4.0 mm at temperatures up to 640 °C, pressure of 3.0 MPa. Dynamic behaviors of coking process due to fuel pyrolysis were experimentally investigated. Coking process was considered to the net result of two simultaneous sub-processes: a deposition process and a removal process. Results indicated that coking process was an unsteady and dynamic one with randomness. During duration period of coking run, the pressure drop across the test channel and the fuel outlet temperature in some degree oscillated. The wall temperature and the pressure drop variation in a wide range became unpredictable, due to the random coke buildup and removal in a short time. However, repeated experiments were carried out to get reliable results of some regular patterns of coking process. The pressure drop exponentially increased and the wall temperature rapidly changed at the initial stage of coking run; and the pressure drop linearly increased but the wall temperature nearly achieved steady state at the following stages. Opposite to the general realization that coke is a thermal resistance layer to reduce heat transfer, surface deposition enhanced the heat transfer during pyrolysis of RP-3 at the test conditions.