Experimental Investigation on Boiling Phenomena of Bi-Layer Composite Porous Wicks Textured With Nano-Porous Layer
Miniature loop heat pipes (mLHP) are envisioned as one of the next generation electronic cooling technologies. They are closed loop, phase-change devices where the working fluid evaporates during heat addition and its flow is maintained by capillary forces developed inside the porous wick lining the evaporator. While they have many advantages such as high heat flux rates and heat rejection far from the heat source, potential problems are often associated with bubble nucleation and boiling incipience in the porous wicks. Bi-layer composite porous wicks consisting of a nano-porous layer textured onto the traditional micro-porous material are thought to possess enhanced capillary wicking, which could benefit mLHP applications. In this context, it is important to also understand their boiling characteristics. Therefore, a boiling heat transfer testing apparatus was developed and used to characterize the boiling incipience of bi-layer porous wicks. These results may guide material selection in the design of mLHP evaporators employing bi-layer porous wicks.