Innovative system to cool spacecraft on long missions

An innovative cooling system developed by a team of mechanical engineers has proven successful in testing aboard the International Space Station.
A team of mechanical engineers at Worcester Polytechnic Institute (WPI) developed an innovative system to cool spacecraft on long missions. Indeed, even if a spacecraft set in shadow is theoretically subjected to very low temperatures, heat is actually the major issue.

When launched into space, spacecrafts are subjected to sunlight, which can heat the machine up to above the boiling point of water unless they have a reflective surface. Moreover, spacecrafts produce a lot of heat from their power systems, electronics, and mechanical parts, and they evolve into a vacuum, with no air to conduct or convect the heat away.

Instead, heat is usually transferred to panels that allow it to be radiated into space. This kind of system generates a lot of noise and vibration.

This is one of the great advantages of the innovation developed by the engineers at WPI: the cooling system is based on electrohydrodynamics (EHD). It uses electrically charged fluids that continuously circulate through tiny tubes in the cooling system, absorbing and carrying heat away from its source. The system creates no noise or vibrations and requires minimal electric power to operate, unlike current mechanical cooling systems.

An experiment is currently being conducted under the name "Electrohydrodynamically Driven Liquid Flow in Parallel Micro-Tubes" to make sure that the system can work properly over a long duration in zero gravity conditions. Launched in February 2017 aboard the SpaceX Dragon SpX-10 commercial resupply craft, it will continue to operate on the International Space Station (ISS) until August 2018.

Another experiment conducted by the same team of engineers is scheduled to launch for the orbiting station in 2021. The new system, called “Electohydrodynamically Driven Liquid Film Flow Boiling”, uses a two-phase, non-mechanical EHD pumping system with a condenser section and a boiling section. In this more-advanced system, the condensed liquid film is electrohydrodynamically pumped toward the heat source, where it boils. The bubbles generated during the boiling are extracted by another EHD mechanism in the absence of gravity, carrying heat away from the heat source. The liquid is then condensed and pumped back to the heat source.

In addition to its potential use as a cooling system for the next generation space stations, the technology is expected to be used in satellites and future long-distance spacecraft. The technology also has applications on Earth, in industrial cooling and heating, ventilation, air conditioning, and refrigeration systems.

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