Browsing by Author "Evans, Chris"
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Item Advanced Oxygen Recovery via Series-Bosch Technology(45th International Conference on Environmental Systems, 2015-07-12) Abney, Morgan B.; Mansell, J. Matthew; Atkins, Bobby; Evans, Chris; Nur, Mononita; Beassie, Rockford D.Advanced oxygen recovery life support for Martian transit and surface missions constitutes a variety of possible architectures. Over the last several years, NASA has pursued development of a two-step Bosch-based system called Series-Bosch (S-Bosch) to enable maximum recovery of oxygen from metabolic carbon dioxide. The first step of the process involves the Reverse Water-Gas Shift (RWGS) reaction. Two RWGS reactors, one developed at NASA and the other developed at Precision Combustion, Inc. have been assembled for the S-Bosch. The RWGS reactors were each tested to evaluate and compare general operational performance and fouling resistance. A down-select was completed to identify the reactor to be used in an integrated S-Bosch system. The second step in the S-Bosch process is carbon deposition. A carbon formation reactor (CFR) based on Martian regolith simulant as a catalyst was designed and tested for performance. Because the regolith will only be available once the crew arrives on the Martian surface, a second catalyst was evaluated for transit phases. Finally, integrated testing of an S-Bosch system was completed, leading to a technology readiness level (TRL) advancement of the S-Bosch system to TRL 4. The results of the RWGS down-select, CFR testing, and TRL evaluation are reported and discussed.Item Alternate Approach to Multi-Layer Insulation Modeling to Reduce Node Count(2023 International Conference on Environmental Systems, 2023-07-16) Peabody, Hume; Evans, ChrisFor models with a limitation on the overall node count, the typical approach to Multi-Layer Insulation (MLI) modeling may generate nodes that are necessary for the analysis, but do not represent components of particular interest. This leaves fewer nodes that can be utilized to model components of greater importance than the MLI. A common approach to modeling MLI is to include a separate MLI node representing the outer layer of the insulation and a radiative coupling based on the area multiplied by an effective emissivity. Therefore, wherever insulation is included, one node is needed for the underlying surface and another node for the insulation. Since many spacecraft and instruments include MLI covering a sizable portion of their designs, this may result in a considerable number of nodes being used for MLI. An alternate method to MLI modeling was developed that eliminates the MLI node, while still preserving the effect of the insulation for the underlying surface, thereby increasing the available nodes that could be used elsewhere in the model. This approach relies on preserving the baseline reflectivity, while reducing the absorptivity (based on the blanket effective emittance) and including a transparency. An inactive second surface is placed just behind the base surface that fully absorbs any energy that is transmitted without including its effect in the model. In essence, this approach applies only the energy that makes it through the blanket to the underlying surface. This method was tested out on the Roman Space Telescope model in local areas in preparation for its use in the generation of a launch model, which is constrained in the allowable node count. This paper documents the performance of the method and presents a comparison between the One-Node MLI method and the traditional two node MLI approach.