Performance Characterization of Water Heat Pipes and their Application in CubeSats

Performance Characterization of Water Heat Pipes and their Application in CubeSats

Brouwer, H.S.B.

Guo, J. (mentor)

Aerospace Engineering

Space Engineering

2016-05-18

The CubeSat platform has long since its introduction surpassed its original intend of being an educational and technology demonstration platform only. The recognition and acknowledgement of its potential has led to an everlasting hunger for more performance, which translates directly into a demand for more power. The power density of CubeSats is rapidly increasing leading to thermal hotspots that can be destructive for any CubeSat mission. The solution proposed to cope with this increase in power density is the water heat pipe: A two-phase, passive thermal control device that is able to transport a large amount of heat without introducing a large thermal gradient over the heat source and sink. For CubeSat application performance characterization tests have been carried out including investigation on its behaviour when bent, tilted against gravity, and frozen. Tests were carried out with commercial copper heat pipes with a diameter of 6mm and 200mm in length (fitting the CubeSat’s structural dimensions) for three different wick structures; axial grooved, mesh, and sintered. The results showed that the axial grooved and sintered heat pipes were easily capable of transporting more than the expected heat loads (10W OAP) for nextgeneration CubeSats without introducing large thermal gradients between heat source and sink. The performance of heat pipes is characterized by an increase in heat transfer coefficient for higher heat pipe temperatures, while at temperatures below the freezing point of water only pure copper conduction remains. Successful start-up from the frozen state was accomplished while repetitive freeze/thaw cycling showed no internal or external damage. Finally, CubeSat integration tests showed that the heat pipe was able to achieve ?T reduction of 45.6°C for a heat load of 3W. It also proved to be successful in removing a continuous 10W heat input, while keeping the PCB chip temperature within limits. The critical aspect in integrating a heat pipe in the CubeSat platform is attaining an efficient heat transfer between the heat pipe and the source and sink. For this, a proper design is necessary to reduce the thermal gradients between these interfaces. Furthermore, the heat pipe is perfect for heat transport but will create a hotspot at the chosen heat sink element of the CubeSat if no other thermal control mechanisms are involved which is able to remove this heat from the satellite.

heat pipes
CubeSat
thermal control

http://resolver.tudelft.nl/uuid:219151e3-aac4-4cc7-8fb4-535e525d0297

Student theses

master thesis

(c) 2016 Brouwer, H.S.B.