Thermo-hydraulic analysis of the flat plate pulsating heat pipe tested under μ–gravity conditions
Maksym Slobodeniuk1, ⋆,
Rajalakshmi Ravichandran2,
Remi Bertossi3, Vincent
Ayel2, Cyril Romestant2, Yves Bertin2
⋆ : maksym.slobodeniuk@ensma.fr
1 IPSA;
ISAE-ENSMA
2
ISAE-ENSMA
3 IPSA
Mots clés : Pulsating Heat Pipe, Microgravity, Thermal
Performance, Flow Transition
Résumé :
The high power and performance electronic devices in modern
spacecraft systems with heat generation of hundreds of Watts per square
centimeter crucially increases needs in high performance, low weight,
energy efficient and reliable thermal management systems. Pulsating Heat
Pipe (PHP) as a passive two-phase heat transfer device based on phase
change induced motions of working fluid from evaporator to condenser
could become a novel thermal management system due to high heat transfer
capability, simple structure and ability of operating under different
gravity levels and different positions. However, this relatively new
technology with very complex thermo-hydrodynamic mechanisms inside is
not fully studied and needs further investigations.
This work presents synthesis of the results obtained during 64th and
69th ESA Parabolic Flight Campaigns for the flat plate pulsating heat
pipe tested under microgravity conditions in order to thermal
performance investigations and liquid-vapor interfaces oscillation
influence on the flow pattern inside the device.
Tested flat plate pulsating heat pipes represent a copper (64th PFC) /
molybdenum (69th PFC) plate with milled squire shape channels (1.5 and 3
mm2) covered by the sapphire
cover plate to allow visual analysis of the flow inside. Ethanol and
dielectric fluid FC-72 were chosen as working fluids with volumetric
filling ratio of 50 %.
Microgravity periods are mostly characterized by the significant
temperature augmentation in the evaporator zone. This temperature rise
is a result of fluid accumulation in the condenser and dry-out of
evaporator ? heat transfers only by the FPPHP wall conduction.
Sometimes evaporator temperature drops because of flow pattern change
from slug-plug to semi-annular and fluid reflows to the evaporator. This
phenomenon was called “flow re-activation” and observed only for few
cases during microgravity phases. Video post-processing was performed to
define flow parameters influencing flow transition for microgravity
conditions, as well as to determine liquid plugs velocities and
accelerations. Classical criteria (We, Bo, Ga, Fr) used for slug-plug
flow pattern definition were validated. Finally, the acting forces
during stopover and re-activation were calculated.
doi : https://doi.org/10.25855/SFT2022-109
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