Browsing by Author "Serio, Michael A."
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Item Adsorption of Ammonia on Regenerable Carbon Sorbents(45th International Conference on Environmental Systems, 2015-07-12) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Wilburn, Monique S.Results are presented on the development of reversible sorbents for the combined carbon dioxide, moisture, and trace-contaminant (TC) removal for use in extravehicular activities, and more specifically in the Primary Life Support System. The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Data on sorption and desorption of ammonia, which is a major TC of concern, are presented in this paper. The current TC-control technology involves the use of a packed bed of acid- impregnated granular charcoal, which is non-regenerable. The carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. In this study, several carbon sorbents were fabricated and tested for ammonia sorption. Ammonia-sorption capacity was related to carbon pore structure characteristics, and the temperature of oxidative carbon-surface treatment was optimized for enhanced ammonia- sorption performance.Item An Equivalent System Mass (ESM) Analysis for the Universal Waste Management System (UWMS) with and without the Torrefaction Processing Unit (TPU)(2020 International Conference on Environmental Systems, 2020-07-31) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Lee, Jeffrey M.Equivalent System Mass (EMS) is one of the metrics commonly used in the evaluation of new systems, often performed as part of trade studies. ESM is a technique that makes it possible to reduce several physical quantities describing a system, or a subsystem, to a single parameter expressed in the units of mass. ESM has the following five components: (1) mass; (2) volume; (3) power; (4) cooling; and (5) crewtime. In this paper, results of an ESM analysis are reported for the Torrefaction Processing Unit (TPU) and the Metabolic Solid Waste Storage (MSWS), both considered in conjunction with the Universal Waste Management System (UWMS). The TPU involves sterilization of human solid waste via mild non-oxidative thermal treatment (torrefaction) to produce a stable, relatively odor-free solid product. This product can be easily stored, or recycled, and TPU operation is associated with the simultaneous water recovery from the solid waste. The TPU is designed to be compatible with the UWMS, now under development by NASA. In contrast to the TPU, the MSWS involves no waste processing, which results in the need to store large amounts of unprocessed solid waste. A stand-alone TPU could be used to treat the contents of a waste canister from the UWMS, thus allowing the waste canister to be reused, which significantly reduces the number of canisters required on board. An ESM analysis was performed for the TPU and for the MSWS, and results were compared for the case of a Mars mission and a four-person crew. Results show that the use of the TPU is associated with some advantages as compared with the MSWS, even though system design is more complex.Item Carbon-Based Regenerable Sorbents for the Combined Carbon Dioxide and Ammonia Removal for the Primary Life Support System (PLSS)(44th International Conference on Environmental Systems, 2014-07-13) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Manthina, Venkata; Singh, Prabhakar; Chullen, CindaResults are presented on the development of reversible sorbents for the combined carbon dioxide and trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs). Since ammonia is the most important TC to be captured, data on TC sorption presented in this paper are limited to ammonia, with results relevant to other TCs to be reported at a later time. The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Furthermore, the current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. The objective of this study was to demonstrate the feasibility of using carbon sorbents for the reversible, concurrent sorption of carbon dioxide and ammonia. Several carbon sorbents were fabricated and tested, and multiple adsorption/vacuum-regeneration cycles were demonstrated at room temperature, and also a carbon surface conditioning technique that enhances the combined carbon dioxide and ammonia sorption without impairing sorbent regeneration.Item Co-Adsorption of Ammonia and Formaldehyde on Regenerable Carbon Sorbents for the Primary Life Support System (PLSS)(46th International Conference on Environmental Systems, 2016-07-10) Wojtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Wilburn, Monique S.Results are presented on the development of a reversible carbon sorbent for trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is deemed non-regenerable, while the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. Data on concurrent sorption and desorption of ammonia and formaldehyde, which are major TCs of concern, are presented in this paper. A carbon sorbent was fabricated by dry impregnation of a reticulated carbon-foam support with polyvinylidene chloride, followed by carbonization and thermal oxidation in air. Sorbent performance was tested for ammonia and formaldehyde sorption and vacuum regeneration, with and without water present in the gas stream. It was found that humidity in the gas phase enhanced ammonia-sorption capacity by a factor larger than two. Co-adsorption of ammonia and formaldehyde in the presence of water resulted in strong formaldehyde sorption (to the point that it was difficult to saturate the sorbent on the time scales used in this study). In the absence of humidity, adsorption of formaldehyde on the carbon surface was found to impair ammonia sorption in subsequent runs; in the presence of water, however, both ammonia and formaldehyde could be efficiently removed from the gas phase by the sorbent. The efficiency of vacuum regeneration could be enhanced by gentle heating to temperatures below 60 °C.Item The Development of Carbon-Based Sorbent Monoliths – a Review(2023 International Conference on Environmental Systems, 2023-07-16) Wojtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Carlson, Andrew E.; Chullen, CindaItem Development of Trace Contaminant Control Prototypes for the Portable Life Support System (PLSS)(47th International Conference on Environmental Systems, 2017-07-16) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Nalette, Tim; Guerrero, Sandra V.; Papale, William; Wilburn, Monique S.Results will be presented on the development of a reversible carbon sorbent for trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. Data on sorption and desorption of ammonia and formaldehyde, which are major TCs of concern, as well as pressure-drop calculations were used to design and test 1/6-scale and full-scale trace contaminant control system (TCCS) prototypes. Carbon sorbents were fabricated in both the granular and foam-supported forms. Sorbent performance was tested for ammonia sorption and vacuum regeneration in 1/6-scale, and pressure-drop characteristics were measured at flow rates relevant to the PLSS application.Item Monolithic Trace-Contaminant Sorbents Fabricated from 3D-printed Polymer Precursors(49th International Conference on Environmental Systems, 2019-07-07) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Carlson, Andy; Chullen, CindaThe current trace-contaminant (TC) removal technology for use in Extravehicular Activities (EVAs) involves the use of a packed bed of acid-impregnated granular charcoal, which is difficult to regenerate. In this paper, results will be presented on the development of vacuum-regenerable TC sorbents for use in the Portable Life Support System (PLSS). The sorbents will be derived from 3D-printed polymer monoliths (e.g., honeycomb structures), which will then be carbonized and oxidized in order to develop porosity, and also to enhance the TC-sorption capacity. Results will be presented on the following aspects of carbon-sorbent development: (1) precursor selection; (2) monolith fabrication; (3) shape retention and strength; (4) carbon surface and porosity characterization; (5) TC-sorption capacity and vacuum-regeneration; (6) pressure drop; and (7) sub-scale sorbent prototype. The use of predominantly microporous monolithic carbon is associated with the following benefits: (a) high TC-sorption capacity; (b) low pressure drop; (c) rapid vacuum (pressure-swing) desorption due to thin monolith walls and low pressure drop; (d) good thermal management (high thermal conductivity and low adsorption/desorption thermal effects associated with physisorption); and (e) good resistance to dusty environments.Item Pressure-Swing Adsorption of Trace Contaminants Using Carbon Sorbent Monoliths(50th International Conference on Environmental Systems, 7/12/2021) W�jtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Carlson, Andrew E.; Hostetler, John M.; Espinosa, Nicolas J.; Chullen, CindaThe current trace-contaminant (TC) control technology involves a packed bed of acid-impregnated granular charcoal, which is difficult to regenerate, and this sorbent is at present considered a consumable. The preferred implementation of TC control is pressure-swing adsorption (PSA) using a regenerable sorbent, where TCs are adsorbed on the sorbent in adsorption steps, which are followed by sorbent regeneration by exposure to space vacuum (desorption steps). The adsorption-desorption steps are repeated cyclically in parallel beds, which ensures continuous TC removal. A similar approach has been used in carbon-dioxide control, with a cycle time of a few minutes, and it is desirable to adopt the same time scale in TC control. In addition, the use of sorbent monoliths is advantageous due to the low pressure drop and low fan-power requirement. In this paper, results are presented on the development of vacuum-regenerable TC sorbents for use in the Exploration Portable Life Support System (xPLSS). The sorbents were derived from 3D-printed polymer monoliths (e.g., honeycomb structures), which were then carbonized and oxidized in order to develop porosity, and also to enhance the TC-sorption capacity. Results are presented on the following aspects of carbon-sorbent development: (1) monolith fabrication; and (2) sorbent-performance in terms of TC-sorption and vacuum-regeneration. The use of predominantly microporous carbon monoliths is associated with the following benefits: (a) high trace contaminant sorption capacity; (b) low pressure drop; (c) rapid vacuum (pressure-swing) desorption due to thin monolith walls and low pressure drop; (d) high mechanical strength [2,3] and resistance to attrition; (e) good thermal management (high thermal conductivity and low adsorption/desorption thermal effects associated with physisorption); (f) good resistance to dusty environments; (g) non-toxic, non-flammable sorbents made of high-purity carbon; and (h) the flexibility to 3D-print/fabricate sorbent monoliths with optimized channel geometries that ensure uniform flow distribution throughout the sorbent.Item Space Applications of Torrefaction Processing(45th International Conference on Environmental Systems, 2015-07-12) Serio, Michael A.; Cosgrove, Joseph E.; Wójtowicz, Marek A.; Lee, Jeffrey; Wignarajah, Kanapathipillai; Fisher, JohnA recent study addressed the technical feasibility of a torrefaction (mild pyrolysis) processing system that could be used to sterilize feces and related cellulosic biomass wastes (food, paper, wipes, and clothing) in space, while simultaneously recovering moisture, producing additional water, and small amounts of other useful products (e.g., CO2, CO, and CH4). This work was done using bench scale torrefaction processing units and examined different modes of heating (conventional and microwave). The amounts of solid vs. gas plus liquid products could be controlled by adjusting the torrefaction conditions, especially the final temperature and holding time. The solid char product from a fecal simulant was a dry, free flowing powder that did not support bacterial growth and was hydrophobic relative to the starting material. The proposed torrefaction approach has potential benefits to NASA in allowing for solid waste sterilization and stabilization, planetary protection, in-situ resource utilization (ISRU) and/or production of chemical feedstocks and carbon materials. In particular, the torrefaction char residue has several potential applications in space. These include production of activated carbon, a nutrient-rich substrate for plant growth, construction material, radiation shielding, storage of elemental carbon, hydrogen, or oxygen, and fuel gas (CH4, CO, and H2) production. The current paper provides additional torrefaction data and analysis. It also addresses the potential space applications of torrefaction processing, how it compares to other approaches to solid waste management, its applicability to a range of cellulosic biomass materials, and how the technology could be integrated with existing advanced life support technologies, such as the Heat Melt Compactor (HMC) or the Universal Waste Management System (UWMS).Item The Effect of Carbonization Conditions on the Performance of Ammonia Sorbents Derived from Polyether Ether Ketone (PEEK)(2020 International Conference on Environmental Systems, 2020-07-31) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Carlson, Andrew E.; Espinosa, Nicolas J.; Hostetler, John M.; Chullen, CindaThe current trace-contaminant (TC) control technology involves a packed bed of acid-impregnated granular charcoal, which is difficult to regenerate. The use of predominantly microporous monolithic carbon produced by carbonization of polyether ether ketone (PEEK) was previously proposed. In this paper, the effect of carbonization conditions on sorbent performance is reported. Although the target application will involve carbon monoliths (e.g., honeycomb structures), granular sorbents were used in this study so that their performance could be compared with the currently used reference carbon (available only in the granular form). The PEEK polymer was carbonized at temperatures 700–1,050 °C, which was followed by carbon activation to a burn-off of 20%. Activation was carried out in a flow of air at 325 °C. The carbon pore structure was characterized using nitrogen adsorption isotherm data. The PEEK-derived sorbents were tested for ammonia sorption in a laboratory packed-bed system. Sorbent regeneration was evaluated by exposing ammonia-saturated sorbents to high vacuum at room temperature for 6 hours, and subsequently re-testing their ammonia-sorption performance. All the PEEK-derived carbons were found to be highly microporous, and their surface area increased with the increasing carbonization temperature. In contrast, the initial equilibrium ammonia sorption capacity was found to decrease as the carbonization temperature increased. All sorbents showed a significant loss of sorption capacity after the first sorption-regeneration cycle, but no performance loss was observed in subsequent cycles. It was found that the presence of oxygen complexes on the carbon surface greatly enhanced ammonia sorption on carbon. In addition, PEEK-derived sorbents were shown to exhibit favorable sorption-regeneration characteristics, as compared with the acid-treated activated carbon.Item The Effect of Trace-Contaminant Sorbent Monolith Geometry on Sorbent Performance(51st International Conference on Environmental Systems, 7/10/2022) Wójtowicz, Marek A.; Cosgrove, Joseph E.; Serio, Michael A.; Carlson, Andrew E.; Chullen, CindaThe current trace-contaminant (TC) control technology in the Exploration Portable Life Support System (xPLSS) involves a packed bed of acid impregnated granular charcoal, which is difficult to regenerate and is considered a consumable. The preferred implementation of TC control is pressure-swing adsorption (PSA) using a regenerable sorbent, where TCs are adsorbed in adsorption steps followed by regeneration by exposure to space vacuum (desorption steps). The adsorption-desorption steps are repeated cyclically in parallel beds, which ensures continuous TC removal. The use of sorbent monoliths is advantageous due to the low pressure drop and low fan-power requirement. TC-sorption capacity is an important sorbent property, which, in conjunction with the gas residence time within the sorbent, strongly affects sorbent performance. Sorbent-monolith geometry plays an important role through the complex mass-transfer and sorption/desorption kinetic phenomena that occur within the sorbent structure. In this paper, results are presented on the development of vacuum-regenerable TC sorbents for use in the xPLSS, with the effects of sorbent-monolith geometry studied in sorption-desorption experiments. The sorbents were derived from 3D-printed polymer honeycomb monoliths that were carbonized and oxidized to develop porosity, and also to enhance the TC-sorption capacity by the creation of carbon-oxygen surface complexes. Results are presented on the following aspects of sorbent-monolith geometry: (1) monolith size (volume); and (2) channel cross-sectional shape and size. The use of predominantly microporous carbon monoliths is associated with the following benefits: high sorption capacity; low pressure drop; rapid vacuum desorption; high mechanical strength and resistance to attrition; good thermal management (high thermal conductivity and low thermal effects associated with physisorption/desorption); good resistance to dusty environments; low toxicity and flammability.Item Torrefaction Processing of Spacecraft Solid Wastes(44th International Conference on Environmental Systems, 2014-07-13) Serio, Michael A.; Cosgrove, Joseph E.; Wójtowicz, Marek A.; Lee, Jeffrey; Wignarajah, Kanapathipillai; Fisher, JohnNew technology is needed to collect, stabilize, recover useful materials, and store human fecal waste and other spacecraft solid wastes for long duration space missions. The system should also require minimal crew interactions, low energy demands, and tolerate mixed or contaminated waste streams. The current study addressed the technical feasibility of a torrefaction (mild pyrolysis) processing system that could be used to sterilize feces and related cellulosic biomass wastes (food, paper, wipes, and clothing), while simultaneously recovering moisture and producing small amounts of other useful products (e.g., CO2, CO, and CH4). This work was done using bench scale torrefaction processing units and examined different modes of heating (conventional and microwave) in laboratory studies. A fecal simulant was tested over a range of process conditions (temperature, holding time and atmosphere), along with selected runs with a sludge derivative (Milorganite), cotton fabric, and wipes. The results demonstrated that microwave heating allowed for careful control of torrefaction conditions for the fecal simulant. The net result was complete recovery of moisture, some additional water production, a modest reduction of the dry solid mass, and small amounts of gas (CO2, CO, and CH4) and hydrocarbon liquid production. The amounts of solid vs. gas plus liquid products can be controlled by adjusting the torrefaction conditions, especially the final temperature and holding time. The solid char product from the fecal simulant was a dry, free flowing powder that did not support bacterial growth and was hydrophobic relative to the starting material. The proposed torrefaction approach has potential benefits to NASA in allowing for solid waste sterilization and stabilization, planetary protection, in-situ resource utilization (ISRU) and/or production of chemical feedstocks and carbon materials. In particular, the torrefaction char residue has several potential applications in space. These include production of activated carbon, a nutrient-rich substrate for plant growth, construction material, radiation shielding, storage of elemental carbon, hydrogen, or oxygen, and fuel gas (CH4, CO, and H2) production.Item Use of Pyrolysis Processing for Trash to Supply Gas (TtSG)(44th International Conference on Environmental Systems, 2014-07-13) Serio, Michael A.; Cosgrove, Joseph E.; Wójtowicz, Marek A.; Lee, Jeffrey; Fisher, JohnTechnologies that reduce logistical needs will be a key component of long term space missions. For this reason, NASA has recently begun a Logistic Reduction and Repurposing (LRR) project. This project involves four hardware oriented tasks: 1) conversion of logistical items to useable products using Heat Melt Compactor (HMC) processing; 2) conversion of trash to supply gas (TtSG) in order to make propellants (e.g., CH4, H2) from solid waste products; 3) use of an Advanced Clothing System (ACS) to reduce mass, volume, and flammability; 4) use of Logistics-to-Living (L2L) technologies to repurpose launch packaging containers. The current paper addresses TtSG technologies, in general, and pyrolysis processing in particular. The overall goal of TtSG is to develop methods to convert trash and other solid waste materials to valuable products (e.g., propellants) plus materials that can benefit the life support system (e.g., oxygen, water). The production of propellants could be especially important, as it would reduce the need to launch fuel to locations beyond earth orbit. In addition, since over 5 kg per day of trash is produced for a crew of 4, there is significant logistical leverage to be gained by this conversion process. Recently, several TtSG processes were evaluated by NASA in laboratory testing using simulated waste streams, including a High Fidelity Waste Simulant (HFWS). In the project that is the subject of the current paper, two-stage pyrolysis processing of the HFWS was studied over a range of conditions, in order to examine the effects of cracking temperature, residence time, gas atmosphere, sample size, etc. For all of these experiments, relatively high yields (0.5 to 10 wt. %) of individual gas products (CO2, CO, CH4, C2H4, C2H2, and H2) were observed, with the total gas yields ranging from ~30 to 45 wt. %. The largest yield was generally a liquid product (~40 to 50 wt. %) that was assumed to be mainly water (based on condensates produced from similar two-stage pyrolysis experiments), while modest amounts of a char product (~10 to 15 wt. %) were formed.