Browsing by Author "Alvarez, Giraldo"
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Item Continued Development of a Liquid Amine Carbon Dioxide Removal System for Microgravity Applications(49th International Conference on Environmental Systems, 2019-07-07) Alvarez, Giraldo; DeGraff, Geoff; Swickrath, Michael; Belancik, Grace; Sweterlitsch, JeffreyCarbon dioxide (CO2) can rapidly accumulate in spacecraft, creating a dangerous breathing environment if not properly controlled. Traditionally, solid adsorbents have been used to capture and release the CO2 generated by crew metabolic activity. Liquid absorbents have generally been avoided, due to the added complexity of handling fluids in a microgravity environment. However, with the advent of advanced manufacturing techniques using three-dimensional printing, a capillary-based gas/liquid contactor and degasser system has been developed and tested. Test data and an accompanying mathematical model have been developed for the contactor portion of the system. Flux rate data were then used to size a concept for application in a spacecraft. Finally, an integrated test stand was configured with the degasser and thermal control equipment. The integrated test stand was operated in a bench-scale format, confirming that the sizing analyses are realistic. A process model for the overall system developed in previous efforts was updated with all of the data collected during the most recent fiscal year. In aggregate, the results of parallel experimentation and modeling efforts continue to be encouraging for alternative liquid amine-based CO2 capture system.Item Development of Low-Toxicity Wastewater Stabilization for Spacecraft Water Recovery Systems(45th International Conference on Environmental Systems, 2015-07-12) Adam, Niklas; Alvarez, Giraldo; Mitchell, Julie L.; Pickering, Karen D.Wastewater stabilization was an essential component of the spacecraft water cycle. The purpose of stabilizing wastewater was twofold. First, stabilization prevents the breakdown of urea into ammonia, a toxic gas at high concentrations. Second, it prevents the growth of microorganisms, thereby mitigating hardware and water quality issues due to biofilm and planktonic growth. Current stabilization techniques involve oxidizers and strong acids (pH=2) such as chromic and sulfuric acid, which are highly toxic and pose a risk to crew health. The purpose of this effort was to explore less-toxic stabilization techniques, such as food-grade and commercial care preservatives. Additionally, certain preservatives were tested in the presence of a low-toxicity organic acid. Triplicate 300- mL volumes of urine were dosed with a predetermined quantity of stabilizer and stored for 2 weeks. During that time, pH, total organic carbon, ammonia, and turbidity were monitored. Preservatives that showed the lowest visible microbial growth and stable pH were further tested in a 6-month stability study. The results of the 6-month study are also included in this paper.