experiment_Impact of Pressure on Flow Heat Transfer Characteristics and Thermal Degradation Properties of n-Undedecane.xlsx

This systematic study investigates the flow, heat transfer, and thermal cracking behavior of n-undecane fuel under supercritical pressures, emphasizing the impact of pressure on the dynamics of fuel heat transfer and the kinetics of thermal cracking. Integrating insights from supercritical fluid research—such as the role of local specific heat capacity in heat transfer and pressure effects on microchannel flow—experiments quantify heat absorption, cracking conversion, and product distribution at 2.5–4.5 MPa. Results show pressure negligibly affects physical heat absorption but modulates chemical heat absorption via pressure-dependent reaction pathways. At fixed conditions (outlet temperature: 650 °C; flow rate: 40 mL/min), increasing pressure from 2.5 to 4.5 MPa enhances cracking conversion by 2.55% and gas production by 2.33%. Elevated pressure (3.5→4.5 MPa) promotes higher-molecular-weight liquid fractions and alkane-dominated gases, suppresses cracking acceleration, and enhances radical reactions (e.g., hydrogen transfer, cyclization). At 620 °C, raising pressure to 4.5 MPa increases gaseous product heat release due to higher gas yields. These findings establish pressure as a critical parameter for optimizing the thermochemical balance between heat transfer and cracking in hydrocarbon fuel systems.