Development of a meter-scale U-shaped Oscillating Heat Pipe for GAPS

Thermal performance of a 6m-long Oscillating Heat pipe (OHP) for balloon-borne General Anti-Particle Spectrometer (GAPS) experiment has been investigated. The developed OHP is a closed loop type and U-shaped due to the mission detector requirements. R410A is selected as the working fluid for the use at low temperature. We achieved a thermal conductance of 18.7 W/K for 150 W heat input with 16 turns at +20 deg-C. We also found for the first time that this large-scale OHP can be operated at low temperatures when the cooling section is cooled from +20 deg-C to -60 deg-C. In addition to the well-known advantages of OHP that it can be simply fabricated and has low sensitivity to the orientation, it is found that the OHP has an adjustability and flexibility to 3-dimensional alignment and wide temperature range.