Session
Session VI: Advanced Technologies 2
Abstract
The use of nitinol (shape memory alloy) tubing for an LHP condenser allows a passive, self deploying heat rejection radiator for small spacecraft. The tubing is “trained” to its deployed configuration, then compactly coiled for launch. When the payload is energized and the condenser heats up, the shape memory alloy changes phase and returns to its trained shape. This paper reports on a NASA sponsored SBIR Phase I program that established the feasibility of the concept. Nitinol tubing was made from available material which had a phase change temperature much higher than desired. It was trained to a simple deployed shape. Since the ends of the LHP condenser are constrained, there are a limited number of basic, possible coiling arrangements. Early experiments used a loop thermosyphon with water working fluid to provide condensing vapor to heat the tubing internally and actuate the shape change. The later experiments used an ammonia loop heat pipe to successfully demonstrate deployment that was actuated by the heat being rejected.
Presentation Slides
Self Deploying Nitinol LHP Radiator for Small Spacecraft
The use of nitinol (shape memory alloy) tubing for an LHP condenser allows a passive, self deploying heat rejection radiator for small spacecraft. The tubing is “trained” to its deployed configuration, then compactly coiled for launch. When the payload is energized and the condenser heats up, the shape memory alloy changes phase and returns to its trained shape. This paper reports on a NASA sponsored SBIR Phase I program that established the feasibility of the concept. Nitinol tubing was made from available material which had a phase change temperature much higher than desired. It was trained to a simple deployed shape. Since the ends of the LHP condenser are constrained, there are a limited number of basic, possible coiling arrangements. Early experiments used a loop thermosyphon with water working fluid to provide condensing vapor to heat the tubing internally and actuate the shape change. The later experiments used an ammonia loop heat pipe to successfully demonstrate deployment that was actuated by the heat being rejected.
