Experimental Investigation of Design Factors on Heat Transfer Performance of meter-scale Oscillating Heat Pipe



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48th International Conference on Environmental Systems


Oscillating heat pipe (OHP) is a heat transfer devices that is made of a long meandering capillary tube and working fluid within it. It transfers heat from heat source to heat sink by oscillation of the working fluid driven by the pressure difference between them without wick structures. Due to its high heat transfer capability and simple / lightweight structure, it is expected to be an ideal candidate for space application.

Flat Heat Pipe, heat transfer device with same mechanism of OHP, size of 300mm is developed by JAXA and successfully worked on the orbit in 2011. However, the comprehensive model for predicting OHP behavior and thermal performance is not yet developed. Especially investigations of relatively larger meter-scale OHP seems to be lacking. Devices that enable long distance heat transfer between heat sauce / sink of wide area is required for thermal design of large-size spacecraft. Design variables such as length of flow path may cause the different heat transfer characteristics which is not found on the smaller one. Therefore, it is important to identify the contributing factor of thermal performance of meter-scale OHP.

In this study, the effect of adiabatic length ratio (length of adiabatic section / total length) and filling ratio on heat transfer performance of meter-scale OHP has been investigated. The OHP has outer dimensions of 1700 ×350 ×4mm. The tube is made of stainless steel with inner and outer diameters of 2.0mm and 1.4mm, and meanders between heating section and cooling section 12 times. Check valves are inserted per turn at adiabatic section. The R-134a is used as a working fluid.

The result shows that the best thermal performance was obtained with the filling ratio of about 50% regardless of its adiabatic length ratio, and heat transfer capability of OHP reached more than 400W.


Masaru Saijo, JAXA
Shun Okazaki, JAXA
Naoko Iwata, JAXA
Hiroyuki Ogawa, JAXA
Yoshiro Miyazaki, Thermal Control Laboratory Inc.
ICES201: Two-Phase Thermal Control Technology
The 48th International Conference on Environmental Systems was held in Albuquerque, New Mexico, USA on 08 July 2018 through 12 July 2018.


Oscillating heat pipe, Pulsating heat pipe, Adiabatic length ratio, Filling Ratio