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

Fritz F Laun, Brenton Taft
Frontiers in Heat Pipes (FHP) 5 - 8 (2014)


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. It is found that: 1) the temperature measurements are the result of many oscillations and may be considered a measurement of bulk heat transfer, 2) it is more accurate to quantify the oscillations of liquid slugs and vapor plugs by using pressure measurements in situ with an OHP, and 3) complex pressure wave forms were observed and a natural frequency could not be determined at the high filling ratio used.


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DOI: http://dx.doi.org/10.5098/fhp.5.8

ISSN: 2155-658X