• deployable
• energy
• flexible heat pipe
• heat exchanger
• hp
• n-pentane
• pulsaiting heat pipe
• thermal resistance

The experimental apparatus presented in this master's thesis is part of a more comprehensive research context, namely that of the three-year TOPDESS (Two-phase Passive thermal devices for Deployable Space Systems) project, which started on 26 September 2019 and is funded by the European Space Agency (ESA). In this thesis, the focus is on the design and operation of a Deployable Metal PHP (DPHP), for a space cooler. The heat exchanger, consisting of capillary tubes, must be able to achieve sufficient flexibility to allow rotation of one of the two ends with respect to the other by approximately 90°. Therefore, following appropriate investigations, the thermomechanical design of the deployable Pulsating Heat Pipe (DPHP), 100 x 160 x 500 mm, revealed that the torsion spring shape of the optimal adiabatic section must have a diameter of 65 mm, a number of N coils equal to 3.5 and an Lcoil length of 715 mm made from ASIS6063 material. Following a literature review, it was noted that although there are studies of planar PHPs with a long adiabatic section, almost no applications concern flexible PHPs made of metallic material. Therefore it was decided to create a 'reference case', where the adiabatic section is not helical but planar, i.e. 'unrolled', so that this could be used as a reference case to verify the thermal performance of the passive heat transfer system. The design and part of the assembly of the two set-ups (planar PHP and DPHP) took place preliminarily at the DSTEC and DICI laboratories of the University of Pisa, and was then completed at the laboratories of the École Nationale Supérieure de Mécanique et d'Aérotechnique (ENSMA) in Poitiers, France, where, in addition to the final assembly phase, the first experimental tests were carried out to understand the fluid-dynamic operation of the apparatus. The main objective of the experimental campaign conducted at the ENSMA laboratories was to investigate the different modes of operation of the current planar PHP by combining the analysis of temperature and pressure trends to evaluate the effect of different parameters (working fluid, F.R and orientation with respect to gravity) on the thermal performance of the device used as a reference with respect to the deployable PHP. N-pentane was chosen as the working fluid, the latter having excellent thermo-fluiodynamic properties. Tests with the three F.R's ( 30, 50 and 70 % ) showed that the device, positioned horizontally, presents stability for a few power ranges; it can be seen that for an F.R of 70 % and 50 % the device presents a very long start-up (after about 150 min), for 10 W and 20 W respectively, while for an F.R of 30 % it can be seen that the device, except in the case of 10 W where it reaches pseudo-stationarity, never manages to reach start-up for power levels above 10 W, in a horizontal position. The test conducted by tilting the device with an F.R of 30 % showed how the PHP operates in oscillating mode for high powers and exhibits start-ups at different power levels that were not observable in the same test conducted at 0 degrees of inclination. The short-term objective will be to test the planar device with other working fluids, identifying the most pertinent one based on the TOPDESS project's safety criteria, finish the instrumentation of the deployable device and test this sut-up first on the ground in order to have comparable data with its planar twin. Following this, the DPHP will be mounted on the NovaSpace rack and will be one of the devices featured in the next parabolic flight campaign promoted by the European space agency.