Browsing by Author "Hansen, Scott W."
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Item Continued Water-Based Phase Change Material Heat Exchanger Development(45th International Conference on Environmental Systems, 2015-07-12) Hansen, Scott W.; Sheth, Rubik B.; Poynot, Joe; Giglio, TonyIn a cyclical heat load environment such as low Lunar orbit, a spacecraft’s radiators are not sized to meet the maximum heat rejection demands. 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 HX’s do not use a consumable, thereby leading to reduced launch mass and volume requirements. In continued pursuit of water PCM HX development two full-scale, Orion sized water-based PCM HX’s were constructed by Mezzo Technologies. These HX’s were designed by applying prior research on freeze front propagation to a full-scale design. Design options considered included bladder restraint and clamping mechanisms, bladder manufacturing, tube patterns, fill/drain methods, manifold dimensions, weight optimization, and midplate designs. Two units, Units A and B, were constructed and differed only in their midplate design. Both units failed multiple times during testing but several learning outcomes resulted. This report highlights the outcomes from these tests and application of the outcomes to a final sub- scale PCM HX which is slated to be tested on the ISS in early 2017. ICES-2015-188Item Water-Based Phase Change Material Heat Exchanger Development(44th International Conference on Environmental Systems, 2014-07-13) Hansen, Scott W.; Sheth, Rubik B.; Atwell, Matt; Cheek, Ann; Agarwal, Muskan; Hong, Steve; Patel, Aashini; Nguyen, Lisa; Posada, LucianoIn 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.