\tScience & Exploration<\/p>\n
\t\t\t\t\t\t23\/10\/2025
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From dew at dawn to a foggy mirror after a shower, condensation is part of our daily lives on Earth. In space, microgravity alters how heat flows through gases and liquids, a potential enemy for spacecraft electronics needing to cool down in extreme environments.<\/p>\n
For the first time, a European experiment is now looking at the shape liquid films take on cooled surfaces aboard the International Space Station.\u00a0A fin-shaped metal is in the spotlight for scientists to better observe fundamental aspects of condensation.<\/p>\n
\t\t\t\t\t\t\tCondensation on Fins experiment – view from above<\/a><\/p>\n The Condensation on Fins experiment is pioneering heat transfer tests in orbit to study the role of capillary pressure \u2013 the force that pulls liquids through tiny spaces, like water climbing up a paper towel \u2013 during film condensation, all without gravity getting in the way.<\/p>\n Whilst this is fundamental physics research to refine mathematical models, the results will have practical applications, such as cooling electronics in smartphones and computers, and optimising industrial coating processes on our planet.<\/p>\n Space missions could also benefit from more efficient heat exchangers to maintain electronics and life support systems at the right temperature.<\/p>\n \tThe fin factor<\/p>\n Refrigerators, air conditioners and radiators use tiny metal fins for a more efficient heat transfer between fluids and gases. The fin shape\u00a0is also critical for space experiments.<\/p>\n \u201cWe are looking for the best fin shape to maximise heat transfer,\u201d says Brice Saint-Michel, ESA project scientist for this experiment.<\/p>\n \t\t\t\t\t\t\tEarth vs space condensation<\/a><\/p>\n The one-centimetre-tall fin made of aluminum alloy gradually becomes soaked with a low surface tension refrigerant \u2013 this volatile fluid can evaporate or condense with little heat. The liquid drains and puddles at the foot of the fin, where a sponge-like material and a pump draw it away.<\/p>\n \u201cMicrogravity conditions allow us to use a large fin without being disturbed by gravity drainage and vapour convection. It is then much easier to see if liquid films take a different shape,\u201d explains Balazs Toth from ESA\u2019s low Earth orbit payload team.<\/p>\n \tKeep cool and carry on <\/p>\n Greyscale footage shows how vapour condenses on the ground (left) and on the International Space Station (right). The footage is sped up five times \u2013 the whole clip took around one minute in real time.<\/p>\n On Earth the liquid puddles at the foot of the fin, whereas in microgravity the liquid accumulates on the entire fin surface.<\/p>\n \t\t\tCondensation defying gravity \u201cThe liquid seems to be attracted to cold surfaces as a safe place to go, unlike what happens with heat transfer on Earth,\u201d says Andrey Glushchuk from the Centre for Research and Engineering in Space Technologies (CREST<\/a>) at the Universit\u00e9 Libre de Bruxelles, Belgium.<\/p>\n \u201cAny thermal system designed with ground standards won\u2019t work in microgravity. We need to create new designs with novel concepts in mind,\u201d he adds.<\/p>\n The two pointy fingers on each side are part of the experiment as reference objects for calibration. They are made of thermally stable nickel-iron alloy.\u00a0During every run, the condensed liquid is continuously drawn by a sponge-like material at the foot of the fin, pumped, and re-evaporated in a closed loop.<\/p>\n A high-precision interferometer records the temperature and vapour concentration changes around the fin, as well as tracking the liquid film thickness.<\/p>\n \tTheoretical models flying high<\/p>\n Similar experiments on heat transfer have been enjoying brief bursts of microgravity during parabolic flight campaigns over the last two decades. Knowledge from those flights helped the science team develop a technique to precisely measure the liquid film distribution.<\/p>\n \t\t\t\t\t\t\tTeam Heat Transfer Host<\/a><\/p>\n \u201cWe needed the constant microgravity conditions of the International Space Station; nowhere else could we have achieved this level of stability, accuracy and high resolution in our measurements,\u201d says Andrey.<\/p>\n The scientific community works with several theoretical models to predict how condensation rates would evolve depending on the liquid film thickness distribution. \u201cWe want a formula that applies to all, and this is the first time we have had a wealth of data to consolidate it,\u201d adds Carlo Saverio Iorio, head of CREST at the Universit\u00e9 Libre de Bruxelles.<\/p>\n
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