Dust as a Working Fluid for Heat Transfer

The project known as "Dust as a Working Fluid" demonstrates the feasibility of a dust-based system for transferring heat radiatively into space for those space applications requiring higher efficiency, lower mass, and the need to operate in extreme vacuum and thermal environments –  including operating in low or zero gravity conditions in which the dust can be conveyed much more easily than on Earth.

Researchers (outside of NASA) have investigated the use of granular materials (e.g., mineral dust particles) as a working fluid for solar concentrators and other heat transfer systems. A given volume of dust particles have a higher heat capacity than the same volume of any gas, and mineral granular materials do not easily undergo a phase change like liquids except at extremely high temperatures. Granular materials also provide a medium for integrated energy storage. 

The radiative transfer of heat directly into space using mineral dust particles is a new, revolutionary concept for NASA and for spaceflight in general. Space applications require high efficiency, low mass, and the ability to operate in extreme environments –  including low or zero gravity where dust can be conveyed much more easily than on Earth. This project demonstrates the feasibility of dust-based heat transfer systems for space applications, but also has terrestrial applications. The project demonstrates and quantifies the radiative heat transfer efficiency by using a closed-loop, pneumatic regolith conveyance system in a laboratory experiment to test the critical function, thus achieving TRL 3.