2014-10-202014-10-202014-07-13978-0-692-38220-2ICES-2014-303http://hdl.handle.net/2346/59583Tucson, ArizonaScott W. Hansen, NASA, Johnson Space Center, USARubik B. Sheth, NASA, Johnson Space Center, USAMatt Atwell, University of Texas, USADr. Ann Cheek, University of Houston, USAMuskan Agarwal, University of Houston, USASteven Hong, University of Houston, USAAashini Patel, University of Houston, USALisa Nguyen, University of Houston, USALuciano Posada, University of Houston, USAThe 44th International Conference on Environmental Systems was held in Tuscon, Arizona, USA on 13 July 2014 through 17 July 2014.In a cyclical heat load environment such as low Lunar orbit, a spacecraft’s radiators are not sized to reject the full heat load requirement. Traditionally, a supplemental heat rejection device (SHReD) such as an evaporator or sublimator is used to act as a “topper” to meet the additional heat rejection demands. Utilizing a Phase Change Material (PCM) heat exchanger (HX) as a SHReD provides an attractive alternative to evaporators and sublimators as PCM HXs do not use a consumable, thereby leading to reduced launch mass and volume requirements. Studies conducted in this paper investigate utilizing water’s high latent heat of formation as a PCM, as opposed to traditional waxes, and corresponding complications surrounding freezing water in an enclosed volume. Work highlighted in this study is primarily visual and includes understanding ice formation, freeze front propagation, and the solidification process of water/ice. Various test coupons were constructed of copper to emulate the interstitial pin configuration (to aid in conduction) of the proposed water PCM HX design. Construction of a prototypic HX was also completed in which a flexible bladder material and interstitial pin configurations were tested. Additionally, a microgravity flight was conducted where three copper test articles were frozen continuously during microgravity and 2-g periods and individual water droplets were frozen during microgravity.application/pdfengPresentation