Performance Map and Comparative Assessment of Miniature Flat Two-Phase Devices

This study focuses on the comparative assessment of twelve mini flat-plate heat pipe technologies with different internal structures but identical external dimensions (100 × 55 × 2.6 mm³). The devices were fabricated via diffusion bonding and tested under identical boundary conditions using deionised water as the working fluid. Configurations included thermosyphon, screen mesh, grooved, sintered, twisted-wire, hybrid wick heat pipes, loop heat pipes (LHPs), and pulsating heat pipes (PHPs). Performance was assessed based on overall thermal resistance and evaporator temperature under various heat loads in horizontal orientation. An evaporator temperature operating map and a performance map were developed, correlating heat load, heat flux, evaporator temperature, and thermal resistance simultaneously across all technologies. These tools enable designers to rapidly identify the most suitable configuration according to operating temperature limits and heat dissipation requirements, addressing a clear gap in the thermal management literature.