Study on Ignition and Combustion Characteristics of Li/SF 6 based on Closed Thermal Power System

The closed thermal power system employs the combustion of Li/SF6 as the heat source, which can provide power for UUV (Underwater Unmanned Vehicle). The startup and operation stability of the system can be significantly optimized by evaluating the combustion characteristics. Using the visual experimental system, the Li/SF6 combustion process is distinctly observed to be dominated by gas-phase combustion, and the flame is observed to be bright pink. The ignition temperature of Li/SF6 is 473.39 ± 2.00°C in the gaseous atmosphere for an initial pressure of 0.120 MPa and SF6 volume fraction of 75%. Furthermore, a computational model established by adopting the theory of minimum Gibbs free energy is used to estimate the combustion products of Li/SF6. Finally, the gaseous atmosphere of ignition of Li/SF6 is studied. O2 and N2 are not suitable to participate as combustion-supporting gases in the ignition of Li/SF6. Appropriately increasing the initial pressure can effectively reduce the ignition temperature of Li/SF6. To ensure the controlled combustion and safe operation of the closed thermal power system, the recommended initial SF6 volume fraction of the closed thermal power system is 75%.