Embedded Pulsating Heat Pipe for Improved Heat Spreading in CFRP Equipment Panels for Satellites

Abstract

To avoid hot spots on satellites for equipment mounted on Carbon Fibre Reinforced Polymer (CFRP) panels, there is an increasing demand for improved heat spreading. A technology investigated in this paper is embedding a Pulsating Heat Pipe inside a CFRP sandwich panel. A PHP is a meandering tube partly filled with Ammonia effectively achieving an enhanced conductive value above 10,000 W/m/K along the length of the tubing. Although the physics behind the operation of a PHP is not yet fully understood, it can be constructed based on experimental experience available at the Netherlands Aerospace Centre.

The paper describes the design, performance analysis, and manufacturing process of an Engineering Model (EM) of a 0.8 m2 PHP panel. It concludes with performance tests done in a representative environment, achieving TRL 4 to 5. The EM panel has PAN based HT carbon fibre composite face sheets, a carbon foam layer with an embedded pulsating heat pipe tube supported by an aluminium honeycomb. The test programme included leak testing, proof pressure testing, pressure cycle testing, burn-in testing, performance testing in various orientations, and thermal tests in vacuum.

In ambient conditions the PHP performed according to expectations with a heat spreading capability > 300 W/m2. However in vacuum the PHP did not operate at all. This unexpected failure is presented including the root cause investigation. The paper ends with an outlook on further research and potential applications.