Experimental Investigation of in Situ Pressure Measurement of an Oscillating Heat Pipe

Abstract

An investigation using in situ pressure measurements was conducted on an oscillating heat pipe (OHP) to better understand its chaotic nature and the relation between the frequency of oscillations and the thermal performance. The working fluid used was HPLC grade acetone with a 0.8 fill ratio by mass. Three different orientations were tested: top, horizontal, and bottom heating from 100 to 500 W in increments of 50 W. An aluminum water block was used with water at approximately 0°C with a flow rate of 0.9 l/min for the condenser section of the OHP. The condenser and evaporator section were each fitted with a pressure transducer mounted perpendicular to the OHP channel. The pressure and temperature measurements were compared. Complex pressure wave forms were observed and a natural frequency could not be determined at the high filling ratio used.

Microgravity Performance of a Structurally Embedded Oscillating Heat Pipe

“…To read pressure measurements inside the OHP, Swagelok VCR® fittings and Omega pressure transducers were integrated into the panel in both the condenser and evaporator section (pressure measurements are reported separately [11]). After using a helium leak detector to ensure a leak rate of less than 10E − 7 atm · c 3 ∕ sec, vacuum (3E − 3 torr) was pulled on the sealed OHP, and acetone (high-performance liquid chromatography grade) was added with a 0.8 0.01 fill ratio, by mass.…”