FLEX Versus Dual Tank Thermal Management Systems

Modern aircraft designs commonly include a thermal management system that uses fuel as a heat sink to remove excess heat from onboard systems. The topology and control of such thermal management systems substantially impact aircraft flight endurance when restricted by thermal limitations. Two such systems are the dual tank and the FLEX thermal management systems, where FLEX is the proper name of the particular type of system. Recent publications have proposed and analyzed each of their individual design and performance. In this work, the performance bounds of the two systems are explicitly compared and contrasted, focusing on the effects of their topological structure and nominal control design objectives. Three main tasks are tackled. First, defining interesting scenarios for comparing the two systems, such that trivial implementation adjustments do not render the contrasting differences moot. Second, performing a model based analysis to derive the maximum thermal load that each system can dissipate during such interesting scenarios. Third, devise useful procedures and graphics to present the findings of the model based analysis. The derivation and presentation of the parameter dependent maximum thermal load that each system can dissipate is established and can be employed to inform vehicle design and mission planning. The result is a theoretical grounding for comparing and contrasting the two systems in order to properly evaluate their relative advantages and disadvantages when devising an aircraft thermal management system.