  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

Classical Physics;Fluid Dynamics