Evaluation of evaporative heat transfer performance based on observation of Thermo-Fluid behavior in porous structures fabricated by additive manufacturing

• Using additive manufacturing, a porous body and the evaporator case of a loop heat pipe structure was fabricated. • The characteristics of the porous body demonstrated sufficient performance as a wick for the loop heat pipe. • Thermal transfer properties were evaluated through microscopic infrared observation techniques. • Attaching a monolayer porous body to the evaporator case resulted in the most excellent heat transfer coefficient and heat flux. This study focuses on improving the performance of Loop Heat Pipes (LHPs) by investigating the thermo-fluid behavior within the evaporator. Previous observations using infrared and visible techniques have revealed potential improvement methods, such as modifications to vapor groove dimensions and enhancements in evaporator wettability. In this research, additive manufacturing technology is employed to manufacture both porous media and evaporator casings, with the aim of enhancing performance. The study evaluates four types of evaporator structures, including samples fabricated separately for porous media and heating plate corresponding to the evaporator casing, samples fabricated integrally, and samples with a porous monolayer loaded onto the heating plate. Micro-scale infrared observation is utilized to assess evaporative heat transfer coefficients and maximum heat flux. The experimental results demonstrate a substantial increase in maximum heat flux in structures where the porous body and heating plate are integrated into a single unit. Moreover, the investigation reveals the influence of the contact area structure between the porous media and heating plate on performance. The presence of voids in this area, allowing for improved vapor release during nucleate boiling, was found to enhance heat transfer efficiency. These findings underscore the efficacy of employing additive manufacturing technology for optimized evaporator designs, offering a pathway toward structurally enhanced and more efficient evaporators.