A procedure was developed to inject thermal filler material (a paste-like substance) inside the power wire bundle coming from solar arrays. This substance fills in voids between wires, which enhances the heat path and reduces wire temperature. This leads to a reduced amount of heat generated. This technique is especially helpful for current and future generation high-power spacecraft (1 kW or more), because the heat generated by the power wires is significant enough to cause unacceptable overheating to critical components that are in close contact with the bundle.

Powered test results in thermal vacuum showed a significant decrease in temperature with filler of ≈50 °C. Without filler, the bulk wire temperature was around 100 °C, whereas with filler, it was around 50 °C. The heat generated by the bundle was reduced by ≈15 percent. The procedure generated the development of an injection manifold for simultaneous injection around the perimeter of the bundle, which is unique. This manifold ensures a consistent and thorough fill of gaps between wires.

The unique or novel features are twofold. This is the first instance where thermal filler material was used to fill in voids in between wires to enhance thermal path, and reduce wire temperatures and heat generated. The injection manifold designed for the procedure is also unique. A thermal test was performed in order to evaluate the advantages of the use of this procedure. In the test with 2.5 A running through the wires, an approximately 50 °C temperature reduction was measured after the filler injection procedure. Heat conduction path improved by up to a factor of 11, and waste heat generated was reduced by 15 percent.

This work was done by Juan Rodriguez-Ruiz, Russell Rowles, and Greg Greer of Goddard Space Flight Center. GSC-15987-1

NASA Tech Briefs Magazine

This article first appeared in the April, 2011 issue of NASA Tech Briefs Magazine.

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