Executive Summary : | Advancements in technology have led to the development of powerful, miniaturized, and high power density electronic equipment. The need to dissipate high heat flux has increased to maintain safe and reliable operations. Vapor chambers as heat spreaders have gained attention to mitigate hotspots. Vapor chambers are planar heat pipes with a large aspect ratio and thickness less than 10 mm. They have a porous wick lined with working fluid and vapor space at the center. Liquid inside the wick evaporates due to hotspots, condensing on the heat sink side and being passively transported through the wick back to the hotter region. Traditionally, the boiling limit for vapor chambers is the incipience of bubbles inside the wick that impede liquid circulation, leading to dryout. However, recent studies suggest that capillary-fed boiling can be a sustained regime of operation before reaching dryout. Most studies have focused on modifying the wick structure to enhance liquid replenishment via capillary action. This work aims to investigate capillary-fed boiling heat transfer with surface-active ionic liquids (sAILs) and surfactants. These amphiphilic molecules adsorb at the liquid-vapor interface of bubbles, preventing coalescence. Formation of multiple smaller bubbles during capillary-fed boiling with these solutions can significantly increase liquid-vapor meniscus and triple phase contact lines, leading to enhanced evaporation and increased heat dissipation capability. Additionally, numerical investigation of evaporation with these solutions inside the wick structure will enable the development of heat pipes and vapor chambers with increased heat dissipation capacity. |