The world-leading heat pipe research that is heading for orbit

On the ground, most systems rely on the ambient air to deal with the heat that is produced by electricity or combustion. But in space the problem is far more complicated due to the complete absence of air and violent extremes in temperature. This means, for example, that satellites require a thermal radiation screen in order to limit both the excessive heat from the sun and the release of heat to the cold darkness of outer space.

Since the beginning of space exploration thermal management has been a key factor for the success of missions. Systems with an evaporator and condenser, where a fluid is flowing in a channel without the support of a pump, are a common technological choice due to their extremely high performance in heat conduction and low weight.

Explaining the background to his research Professor Marco Marengo said: “In the 1990s Japanese engineer Doctor Hisateru Akachi proposed a new concept for a very simple system able to dissipate heat using an evaporator and a condenser connected through a meandering capillary tube, the so-called pulsating heat pipe. For many years, this idea remained in the drawer without a suitable application or research investigations.

“Early in the new millennium a few scientific papers began to highlight that this system had technical potential and a complex and fascinating set of physical processes worthy of further investigation.”

Beginning in 2009, Professor Marco Marengo, first in Italy and then in Brighton, began to explore the use of the pulsating heat pipe in space, through a series of experiments using parabolic flights, with funding from the European Space Agency.

Parabolic flights are special flights operated by a retrofitted standard airplane such as an Airbus A300, which, using a ballistic trajectory, reproduce a free fall for 20 seconds inside the cabin. During the free fall all the systems and passengers on board are under microgravity conditions replicating those experienced in space. The microgravity experiments on the pulsating heat pipe have not only demonstrated that the system can be used in space, but have led to a new concept, called the Hybrid Pulsating Heat Pipe, which may be used both in terrestrial and in microgravity applications.

This breakthrough has convinced the European Space Agency to grant the team led by Professor Marengo much sought-after access to the International Space Station to conduct a long-duration experiment.

This comes on the back of a recent award of a grant worth over £900k to the University of Brighton from the EPSRC to support the further development of the rack to carry experiments in future parabolic flights which could also host thermo-fluid experiments from other UK and European universities and companies.

The rack will start its operational life with two further sets of parabolic flights in November 2017 during which the new Hybrid Pulsating Heat Pipe will be tested in its final configuration for the International Space Station.

It is hoped that the Hybrid Pulsating Heat Pipe will travel to the International Space Station with British astronaut Tim Peake when he undertakes his second space mission.