Description: During a NASA Phase I SBIR program, ACT addressed the need for light-weight, non-venting PCM heat storage devices by successfully demonstrating proof-of-concept of a vapor chamber with a PCM-based wick structure. The principal objective of the Phase II program is to design, fabricate, and test a full-scale PCM vapor chamber. Goals of the Phase II program include establishing thermal and structural design requirements. ACT will also develop a thermal storage model for integration into the heat transport model developed in Phase I. A custom microPCM will be developed and screened with the assistance of subcontractor SwRI to obtain optimum properties for thermal performance. ACT will also design, fabricate and test a sub-scale PCM vapor chamber with relevant form factor and a fraction of the full-scale heat load. Upon successful demonstration of the sub-scale unit, two full-scale PCM vapor chambers will be fabricated and tested. Both full-scale units will undergo extensive thermal performance testing. At the end of the Phase II project, one of the full-scale PCM vapor chambers will be delivered to NASA for further testing, and the other will remain at ACT for extended life testing.

Benefits: The proposed PCM vapor chamber can operate as both a thermal capacitor and as a two-phase heat exchanger. For NASA applications that have a need for a thermal capacitor, the PCM vapor chamber can provide mass savings to the system by swapping out the existing thermal capacitor with the PCM vapor chamber. For thermal control systems requiring both a thermal capacitor and a liquid/liquid heat exchanger, the PCM vapor chamber can be used as an all-in-one solution. This approach has the potential to provide significant mass savings.

MDA's Airborne Laser (ABL) program has significant cooling requirements that can only be addressed by mechanical refrigeration systems. These include cooling of the various high powered solid state lasers currently used on the ABL for tracking and ranging as well as standby cooling for the basic hydrogen peroxide (BHP) loops on the Chemical Oxygen Iodine Laser (COIL). To reduce size, weight and power consumption, the PCM vapor chamber could be integrated into the refrigeration system to reduce the temperature lift requirement during peak heat load conditions. By using the PCM vapor chamber as a load leveling device, the power requirement of the compressor can be significantly reduced. ACT is also currently working on several other high energy laser cooling applications with military primes and direct government funding programs. These applications require PCM storage to reduce the mass of the thermal control system.