Nano-Textured Wick in Heat Pipes

Abstract

The current work lays emphasis on investigation of theoretical and experimental performance of solution blown polyacrylonitrile (PAN) nanofibers as wick in a Loop Heat Pipe (LHP). Theoretical equations describing the thermal balance, mass balance, volume balance and the state of vapor in a Loop Heat Pipe were modeled. An experimental setup for an LHP, with a flat evaporator base 2.5 cm × 2.5 cm connected to a condenser with an inline flowmeter was set up. Data acquisition system for recording temperature of the heater block and mass flowrate of working fluid was also setup. Deionized water was used as the working fluid. The experimental performance of a thin as well as a thick layer of nanofiber mat was compared to a case with no nanofiber mat as the primary wick. A thin layer of nanofibers provides more efficient cooling by keeping the substrate surface temperature at a lower temperature as compared to a thick layer of nanofiber mat. Substrate surface temperature was higher for both the cases of thick and thin layer of nanofiber mat in comparison to no nanofiber mat as the primary wick. However, a more uniform distribution of working fluid over the substrate surface was evident when using nanofibers as primary wick. The distribution of working fluid in the evaporator chamber was more uniform in the case of thick nanofiber mat as the primary wick as compared to the other two cases. The mass flowrate of water was more linear in case of thick layer of nanofiber mat as the primary wick as compared to a thin layer of nanofiber mat and no nanofiber mat.