Browsing by Author "Waguespack, Glenn"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Design and Analysis of a Fan Outlet Check Valve for the Exploration Portable Life Support System(49th International Conference on Environmental Systems, 2019-07-07) Waguespack, Glenn; Hanford, Anthony; Barnes, BruceCheck valves are required at the outlets of NASA’s Exploration Portable Life Support System (xPLSS) ventilation loop fans to permit forward flow through the ventilation loop while preventing backflow through the fans when they are not running. These check valves must maintain full specified functionality at all orientations in gravitational environments ranging from weightlessness to full terrestrial gravity. A check valve design has been developed to satisfy the above requirements via an iterative process combining mechanical design, computational fluid dynamics (CFD) analysis, Thermal Desktop® analysis, and static force analysis. The initial design concept was a flapper valve in which a mass-balanced flapper freely rotates from fully closed (0°) to a 45° angle, after which a torsional spring engages the flapper to prevent it from opening beyond the point at which reverse flow cannot close the valve. Analysis results, however, indicated that the magnitude of reverse flow induced during contingency purge operations would not always be sufficient to overcome gravitational and frictional moments to close the flapper in its unassisted, free-rotating range. The design was thus revised to provide spring engagement throughout the entire span of valve positions, removing the flapper’s dependency on reverse flow for valve closure. Since commercially-available torsion springs are too stiff for this application, the revised design uses a linear compression spring that engages the flapper at an offset from the flapper’s pivot point. CFD and static force analyses were used to determine acceptable design parameters, from which valve geometry and spring selection were determined.Item A Fecal Processing Technology Trade Study for Water Recovery in Various Mission Duration Scenarios(50th International Conference on Environmental Systems, 7/12/2021) Powell, Camilah; Waguespack, Glenn; Ewert, MichaelTo achieve long endurance human space missions such as a trip to Mars, a fully recycled or "closed loop" water system is almost essential. Even for shorter duration missions in Earth orbit, lunar orbit or on the surface of the moon, recovering and recycling water from as many sources as possible may pay off. One source of water that has not been exploited to date is human solid waste. Herein, a trade study is performed to evaluate the ability of several fecal processing technologies to recover >80% of the water content within the waste. Human solid waste (feces) contains approximately 75% water by mass, which upon quantification, translates to ~170 g of recoverable water per crew member per day and can scale to values of ~680 kg for a crew of 4 persons on a 1,000-day long exploration mission. Several fecal processing technologies (i.e., steam reforming, vacuum drying, freeze drying, pyrolysis, ultrasonic drying, etc.) are analyzed using an equivalent system mass (ESM) approach to assess and compare the estimated cost for recovering fecal water -- in terms of mass, power, and volume equivalents -- against the water recovery mass savings for each technology. Post-use volume, too, is used as a secondary metric for comparison to quantify the benefits of volume reduction resulting from the fecal drying process. From said analysis, clear patterns and benefits emerge that may prove helpful for future fecal processing technology development.