Abstract
The pulsating (called also oscillating) heat pipe (PHP) is a simple capillary tube bent in meander and filled with a two-phase fluid. We discuss numerical simulations of the 10-turn copper-water PHP under vertical favorable (bottom-heated), vertical unfavorable (top-heated), and horizontal orientations. Within the present approach, the horizontal orientation is equivalent to the microgravity conditions. The simulations are performed with the in-house CASCO software. The time-averaged spatial distribution of the liquid plugs inside the PHP is influenced by gravity. This affects the overall PHP performance. We show that, independently of the PHP orientation, contribution of the latent heat transfer is large with respect to the sensible heat transfer. We discuss the phenomena occurring inside the PHP during startup and the stable regimes (intermittent and continuous oscillations followed by dryout).
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Abbreviations
- d :
-
tube inner diameter (m)
- F :
-
evaporator coverage fraction by a phase
- g :
-
gravity acceleration (m2/s)
- L :
-
length (m)
- \(P, \dot Q\) :
-
power (W)
- R t h :
-
heat transfer resistance (K/W)
- T :
-
temperature (K)
- t :
-
time (s)
- ϕ :
-
volume fraction of liquid in PHP
- lat :
-
latent
- sens :
-
sensible
- a :
-
adiabatic
- c :
-
condenser
- d :
-
dry
- e :
-
evaporator
- f :
-
liquid film
- fb :
-
feedback section (vertical in Fig. 1)
- l :
-
liquid plug
- nucl :
-
nucleated
- sat :
-
at saturation
- thr :
-
threshold
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Acknowledgments
The financial contribution of ESA within MAP INWIP is acknowledged. This work has been presented during the joint 19th International Heat Pipe Conference and 13th International Heat Pipe Symposium, Pisa, Italy (2018).
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This article belongs to the Topical Collection: Heat Pipe Systems for Thermal Management in Space
Guest Editors: Raffaele Savino, Sameer Khandekar
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Nekrashevych, I., Nikolayev, V.S. Pulsating Heat Pipe Simulations: Impact of PHP Orientation. Microgravity Sci. Technol. 31, 241–248 (2019). https://doi.org/10.1007/s12217-019-9684-3
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DOI: https://doi.org/10.1007/s12217-019-9684-3