Description: Future manned spacecraft venturing into deep space will require sophisticated thermal control systems to protect against extreme environments ranging from direct illumination by solar radiation to complete darkness. To manage these extremes, heat exchangers composed of phase change materials, which can expand and contract without causing structural damage, will be essential. NASA is seeking non-toxic heat transfer fluids with transition temperatures between 8 and 12 (deg)C with heat of fusion >200 kJ/kg. Specifically, the fluids must have suitable thermal conductivity, high heat capacity, and low viscosity to enable flow with negligible volume expansion. Changes are also needed to reduce the existing heat transfer unit size and weight. InnoSense LLC (ISL) plans to develop new modified ionic liquid-based phase change materials heat exchangers. ISL, in collaboration the University of Nevada, will synthesize salt additives to modulate the operating temperatures, and the thermal and flow properties of the ionic liquid based eutectic phase change material with negligible volume change during phase change. In Phase I, ISL will formulate and test heat transfer formulations in a laboratory environment to demonstrate feasibility. During Phase II, ISL will scale-up synthesis and test fluid performance in a larger experimental apparatus and a wide range of working environments.

Benefits: Future missions will require manned spacecraft to travel further from earth than ever before. A major requirement for these spacecraft is to maintain comfortable living conditions for crewmembers. External temperatures and operating environments vary widely as the craft travels through space. In order to successfully regulate cabin temperature, heat exchangers of minimal size and weight must be implemented. ISL's heat transfer fluid will provide a nontoxic system that will operate effectively in a wide temperature range to maintain cabin temperatures. Our material will enable NASA engineers to design and/or implement a phase change heat exchanger that will offer excellent thermal behavior with negligible volume expansion. By reducing heat exchanger bulk, working space will be maximized.

The proposed heat transfer fluids will find a wide variety of commercial applications. These applications will include the temperature regulation for polar shelters and vehicles. The wide operating range and high heat capacity will aid in the size and weight reduction of existing heat exchangers. Therefore, it will be possible to optimize workable space. Other applications can include the use of the fluid for high powered telescopes, cryogenic fuel utilization sources, and energy generation applications.