Experimental investigation on loop thermosyphon thermal performance with flow visualization

Abstract

A non-phase change heat pipe (NPCHP) with no wick was proposed as a new heat pipe which is not dependent on a wick or phase change at steady state operation and where the heat transfer is driven by the pressure response to a heat input, rather than phase change. It was shown recently that the NPCHP is not a new heat pipe as suggested but is a loop thermosyphon (Kloczko et al., 2019). This effort focuses on understanding how changing different system parameters, including heat input, fill ratio, inclination angle, and working fluid affects the overall system performance of both the single-phase and two-phase loop thermosyphons. Flow visualization is incorporated and the flow of liquid/vapor through the thermosyphon is studied. Depending upon the initial fill ratio of the loop thermosyphon and the working fluid, the thermosyphon is shown to either operate as a two-phase loop thermosyphon or a single-phase loop thermosyphon.