Browsing by Author "Thomas, John"
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Item Development of Carbon Dioxide Removal Systems for Advanced Exploration Systems 2013-2014(44th International Conference on Environmental Systems, 2014-07-13) Knox, James C.; Gauto, Hernando; Gostowski, Rudy; Watson, David; Bush, Richard; Miller, Lee; Stanley, Chris; Thomas, JohnThe Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project was initiated in September of 2011 as part of the Ad- vanced Exploration Systems (AES) program. Under the ARREM project, CO2 removal and associated air drying efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by seek- ing more robust pelletized sorbents, evaluating structured sorbents, and ex- amining alternate bed configurations to improve system efficiency and relia- bility. These development efforts combine sorbent screening and characteri- zation, testing of sub-scale and full-scale systems, and multi-physics comput- er simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. The select- ed subsystem is then implemented in a full-scale integrated atmosphere revi- talization test. This paper describes the carbon dioxide removal hardware design and sorbent screening and characterization effort in support of the ARREM project within the AES program. The development of CO2 removal and associated air-drying subsystem models and simulations under the AR- REM project is discussed in a companion paper.Item Four Bed Molecular Sieve – Exploration (4BMS-X) Virtual Heater Design and Optimization(47th International Conference on Environmental Systems, 2017-07-16) Schunk, Richard; Peters, Warren; Thomas, JohnA 4BMS-X (Four Bed Molecular Sieve – Exploration) design and heater optimization study for CO2 sorbent beds in proposed exploration system architectures is presented. The primary objectives of the study are to reduce heater power and thermal gradients within the CO2 sorbent beds while minimizing channeling effects. Some of the notable changes from the ISS (International Space Station) CDRA (Carbon Dioxide Removal Assembly) to the proposed exploration system architecture include cylindrical beds, alternate sorbents and an improved heater core. Results from both 2D and 3D sorbent bed thermal models with integrated heaters are presented. The 2D sorbent bed models are used to optimize heater power and fin geometry while the 3D models address end effects in the beds for more realistic thermal gradient and heater power predictions.Item Long Duration Sorbent Testbed(46th International Conference on Environmental Systems, 2016-07-10) Howard, David; Knox, James; Long, David; Miller, Lee; Thomas, John; Cmarik, GregThe LDST is a flight experiment demonstration designed to expose current and future candidate carbon dioxide removal system sorbents to an actual crewed space cabin environment to assess and compare sorption working capacity degradation resulting from long term operation. An analysis of sorbent materials returned to earth after approximately one year of operation in the International Space Station’s (ISS) Carbon Dioxide Removal Assembly (CDRA) indicated as much as a 70% loss of working capacity of the silica gel desiccant material at the extreme system inlet location, with a gradient of capacity loss down the bed. The primary science objective is to assess the degradation of potential sorbents for exploration class missions and ISS upgrades when operated in a true crewed space cabin environment. A secondary objective is to compare degradation of flight test to a ground test unit with contaminant dosing to determine applicability of ground testing.