Coupling Simulation Between Coke Deposition and Heat Transfer of Aviation Kerosene

Abstract Air–fuel heat exchange technology is expected to solve the cooling dilemma encountered by advanced gas turbines. Understanding the long-term trends of heat transfer and fuel deposition behavior is crucial for the design of air–fuel heat exchangers. To predict aviation fuel deposition below cracking temperature, an improved kinetic model with 21 bulk and three wall reactions was developed, incorporating two pathways for sulfur-induced deposition in the 300–450 °C range. The dynamic coupling process of fuel deposition and heat transfer within the air–fuel heat exchanger over a 500-h operation was analyzed by using a transient fluid dynamic calculation with the improved deposition model. The growth of the deposit layer of the fuel passage was simulated using dynamic mesh technology. Deposit layer growth alters the flow and heat transfer characteristics of air–fuel heat exchangers, leading to changes in temperature and reactant concentration fields, and ultimately affects the fuel deposition rate in turn. The magnitude of the deposition rate peak contributed by the oxidative deposition decreases, and the peak position shifts downstream with operating time. The peak deposition rate of the fuel passage decreases by 38% after the 500-h operation compared to the initial state. Significant heat transfer deterioration occurs during the initial operation, but the decline in heat transfer efficiency slows down as operating time increases. Using air-saturated fuel caused a 7% air precooling temperature drop after the 500-h operation, while deoxygenated fuel reduced performance decline due to oxidative deposition elimination.