Experimental Investigation of Heat Pipe Flow Dynamics and Performance

Due to their safety, efficiency, and passive operation, heat pipes have found diverse applications that
include nuclear microreactors. Heat pipes enable increased reliability in microreactors as they eliminate
the need for reactor coolant pumps and their associated auxiliary systems, which also results in
greatly reduced spatial footprint. Experimental work is needed to support and expedite the design and
licensing of heat pipe microreactors, especially on the validation of heat pipe performance as key heat
transfer components. The present work develops a comprehensive heat pipe experimental database
covering a wide range of heat pipe operating conditions. The operating conditions are determined based
on previously developed scaling laws for heat pipes and two-phase thermosyphons using low temperature
working fluids. The tested heat pipe is about two meters long and equipped with in-house developed
annulus-screen wicks. To allow the investigation of heat pipe flow dynamics, various instruments
are incorporated to acquire heat pipe pressures, pressure drops, and temperatures. In particular, a fiber
optic sensor is implemented to measure temperatures along the centerline of the entire heat pipe. The
results can be directly applied to the advancement of numerical tools currently under development for
heat pipe microreactor analysis.