Credit: NASA

Boiling fluids behave differently in space and on Earth, suggesting that new approaches are needed to cool spacecraft in orbit.

Heat pipes suck excess heat away from laptop computers and other devices, and consist of a tube filled with liquid that evaporates at one end when heated. The vapour flows to the cool end, then condenses and returns to the other end. Joel Plawsky of Rensselaer Polytechnic Institute in Troy, New York, and his colleagues sent a heat-pipe experiment to the International Space Station (pictured), where the transparent, pentane-containing pipe was heated.

Surprisingly, the liquid did not rush away from the hot end as it does on Earth, but instead flooded the heated area. In zero gravity, capillary forces pulled liquid towards the hot end, whereas on Earth, gravity counteracts these forces.

Phys. Rev. Lett. 114, 146105 (2015)