Calibration and Sensitivity of a Fixed-Bed Adsorption Model for Atmosphere Revitalization in Space



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47th International Conference on Environmental Systems


Solid sorbents offer a reliable and efficient means of carbon dioxide separation in space applications. Adsorbent-based technologies are currently used for atmosphere revitalization onboard the International Space Station (ISS) and are a promising candidate for deep-space travel. Ongoing research is maturing the existing ISS system to enable human space exploration beyond low-Earth orbit. These efforts hinge on the development of an accurate predictive model of the adsorbent-based system to act as a virtual laboratory for optimizing design and operation parameters for next-generation systems. In particular, the sensitivities of the model outputs to changes in input parameters must be understood and quantified. This paper analyzes the sensitivity of a one-dimensional fixed-bed adsorption model; specifically, we consider the effects of the linear-driving-force (LDF) mass transfer coefficient, axial dispersion, and sorbent thermal properties on the breakthrough time, total bed capacity, and effluent temperature profile. The model is first calibrated with data from a small-diameter, cylindrical breakthrough test using intra-bed centerline concentration measurements to find the LDF coefficients. We then use this LDF coefficient to extract axial dispersion coefficients from mixed, downstream concentration measurements for both the small-diameter bed and a large-diameter bed. These two test stands represent the extremes of purely pellet-driven dispersion in large-diameter beds versus wall channeling dominated dispersion in small-diameter beds. We find that the model is most sensitive to the LDF coefficient, sorbent density, and bed void fraction. This paper contributes to the discussion on the role of predictive adsorption models in designing systems for space travel.


Karen N. Son, Purdue University, USA
Justin A. Weibel, Purdue University, USA
Suresh V. Garimella, Purdue University, USA
James Knox, NASA Marshall Space Flight Center (MSFC), USA
ICES300: ECLSS Modeling and Test Correlations
The 47th International Conference on Environmental Systems was held in South Carolina, USA on 16 July 2017 through 20 July 2017.


Air Revitalization, Atmosphere Revitalization, Carbon Dioxide (CO2) Removal, Life Support, Sensitivity Analysis