Browsing by Author "Pace, Gregory"
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Item An Assessment of the Water Extraction Capabilities of the Heat Melt Compactor(44th International Conference on Environmental Systems, 2014-07-13) Alba, Richard; Harris, Linden; Wignarajah, Kanapathipillai; Fisher, John; Hummerick, Mary; Pace, Gregory; Delzeit, Lance; Larson, BrianThe Heat Melt Compactor (HMC), a waste management technology developed at the NASA Ames Research Center, was designed to process waste generated aboard spacecraft. The device compacts, encapsulates and sterilizes the waste in preparation for onboard storage. In addition, the unit removes and recovers water, which is ultimately recycled1, rendering the encapsulated waste inhospitable to microbial contaminants. Initial studies indicate that the HMC is capable of removing and capturing 90 to 98% of the water contained in the process waste sample.2 The nineteen experiments conducted at ARC described in this paper attempt to refine, quantify and define the limitations of the Heat Melt Compactor's dewatering and water collection capabilities. The amount of water in the initial waste sample was measured and found to be 19.04% by weight for batches made at ARC and 20.45% for those made at KSC. This was less than the percentage predicted from the standard waste model. The amount of water recovered and collected varied from 12.9 to 98.4% of initial water contained in the waste. For the six tiles tested, the amount of water remaining in the tiles after processing ranged from 6.97 to 37.67%. The water activity for five of these tiles averaged 0.472; all of these issues play a significant role in the survival and propagation of microorganisms. Water activity values below 0.6 inhibit microbial growth. Significant correlation was found to exist between Percent Water Recovery, Percent Expected Water Encapsulated in Tile and Water Activity, the latter two of which are inversely proportional to water recovered. Percent Water Recovery, since it is easily computed, can be used to predict the other two values.Item Development of an Adsorption System for the Trash Compaction Processing System designed for operation in the International Space Station Express Rack(2020 International Conference on Environmental Systems, 2020-07-31) Pace, Gregory; Lee, Jeff; Parodi, Jurek; Richardson, Justine; Trieu, Serena; Young, Janine; Martin, KevinA water recovery system that utilizes adsorption to work with the Trash Compaction Processing System, formerly known as the Heat Melt Compactor, is being designed at NASA Ames Research Center as an option to current state of the art micro-gravity water management systems and contaminant control systems used in space. The adsorption system will be used in conjunction with the International Space Station Vacuum Exhaust system to avoid both the complexities of gas liquid phase separation in micro-gravity and venting of Trash Compaction Processing System effluents to the spacecraft cabin. The adsorption system will allow the water and gaseous effluents generated during the Trash Compaction System operation to be removed in a matter that meets the Vacuum Exhaust System venting rate requirements. The Trash Compaction Processing System is planned to fly as a Technology Demonstration on the International Space Station in the space station EXPRESS Rack facility. This paper describes the trade space that the adsorption system must operate in using the EXPRESS Rack facilities resources including the use of the Space Station Vacuum Exhaust System. Also described in this paper are design solutions to allow the adsorption system to function within the Express Rack and Vacuum Exhaust System Parameters.Item Gas Effluent Analysis of the Heat Melt Compactor(2020 International Conference on Environmental Systems, 2020-07-31) Young, Janine; Trieu, Serena; Parodi, Jurek; Richardson, Tra-My Justine; Lee, Jeffrey; Martin, Kevin; Pace, GregoryThe Heat Melt Compactor (HMC) reduces volume, heat sterilizes, stabilizes, and manages gas and water effluent of the International Space Station (ISS) trash. Processing the trash at high temperatures produces volatile gas compounds that need to be treated before venting to cabin and/or the Vacuum Exhaust System (VES) in the ISS. The release of gases may not meet the Spacecraft Maximum Allowable Concentrations (SMAC) requirement, if vented directly into cabin, and/or gases are incompatible for venting to the VES. In order to assess the HMC gas release and venting parameters, effluent gas analysis is conducted to determine contaminant load. This paper will analyze different collection and analytical methods of the effluent gas, and report corresponding data, such that these results can be used for process design and effluent management.Item Generation 2 Heat Melt Compactor Development(44th International Conference on Environmental Systems, 2014-07-13) Turner, Mark F.; Fisher, John W.; Broyan, James; Pace, GregoryNASA has been developing a waste management device for human space exploration missions called the Heat Melt Compactor (HMC) as part of the Advanced Exploration Systems (AES) Human Spaceflight Logistics Reduction and Repurposing (LRR) project. Human space missions typically generate trash with a quantity of plastic that is twenty percent or greater by mass. The plastic rich trash contains valuable water entrained in food residue and sanitary wipes blended with paper, duct tape, rubber gloves, and other sundry trash items. The Heat Melt Compactor was designed to provide high trash volume reduction, microbial stabilization, and resource recovery including water and potentially radiation shielding material from the trash. The Heat Melt Compactor dries, compresses, and encapsulates the waste inside the plastic producing a tile that has the consistency of hard plastic. This paper provides an overview of the engineering efforts associated with development of a second generation HMC. The Gen 2 HMC is a ground based prototype unit that has been designed to function within the physical and environmental constraints of an International Space Station (ISS) Express Rack and serves as a precursor to developing proto-flight hardware.Item Heat Melt Compactor Development Progress(47th International Conference on Environmental Systems, 2017-07-16) Lee, Jeffrey; Fisher, John; Pace, GregoryThe status of the Heat Melt Compactor (HMC) development project is reported. HMC Generation 2 (Gen 2) has been assembled and initial testing has begun. A baseline mission use case for trash volume reduction, water recovery, trash sterilization, and the venting of effluent gases and water vapor to space has been conceptualized. A test campaign to reduce technical risks is underway. This risk reduction testing examines the many varied operating scenarios and conditions needed for processing trash during a space mission. The test results along with performance characterization of HMC Gen 2 will be used to prescribe requirements and specifications for a future ISS flight Technology Demonstration. We report on the current status, technical risks, and test results in the context of an ISS vent-to-space Technology Demonstration.Item Membrane Distillation Driven by Embedded Thermoelectric Heat Pump(48th International Conference on Environmental Systems, 2018-07-08) Lee, Jeffrey; Delzeit, Lance; Parodi, Jurek; Pace, Gregory; Trieu, SerenaMembrane distillation is a method that recovers clean water from dirty water by way of the vapor pressure difference of water across a membrane. External systems typically provide the heat necessary to maintain the vapor pressure difference by warming the feed stream and cooling the permeate stream. These external systems can be of significant mass and can have large thermal losses that are not desirable for space missions. To address the issue, we propose embedding thermoelectric Peltier devices at the membrane surface. The thermoelectrics, acting as heat pumps, provide heating of the warm feed while at the same time cooling of the cold permeate at the membrane surface, thereby eliminating the need for external heating and cooling systems. This paper describes our research and findings for this new method of membrane distillation.Item Processing of Packing Foams Using Heat Melt Compaction(44th International Conference on Environmental Systems, 2014-07-13) Harris, Linden; Alba, Richard; Wignarajah, Kanapathipillai; Fisher, John; Monje, Oscar; Maryatt, Brandon; Broyan, James; Pace, GregoryFoam is used extensively as packing material for items sent to the International Space Station (ISS). Although lightweight, foam is bulky and can occupy a large fraction of the limited ISS volume. Four chemically distinct foams have been used on the ISS. In descending order of current usage, these are Plastazote > Zotek > Minicel > Pyrell. Processing foam with the Heat Melt Compactor (HMC), a solid waste treatment system, has been proposed to reduce the volume of foams stored on spacecraft. Prior to HMC testing, Thermogravimetric Analyses were conducted on the four foams as a precaution to ensure that the thermal decomposition temperatures were not within range of HMC operation (≤180°C). Pyrell was not tested with the HMC because it is known to release toxic compounds and comprises less than 1.5% of total foam usage on ISS resupply flights. Zotek, Minicel, Plastazote LD24FR (low density), and Plastazote LD45FR (high density) were processed with the HMC at 130, 150 and 170°C. Volume was reduced by 82.6% on average (n=19; std dev=4.88). Hydrocarbons and several other compounds emitted during foam processing were measured using a Total Hydrocarbon Analyzer and FTIR. Effects of process temperature and foam type on exhaust composition are discussed. Feeding of foams into the limited size opening of the HMC compaction chamber is likely to be a challenge, particularly in microgravity. Some suggestions are proposed to facilitate feeding foam into the HMC. Processing packing foam with the HMC has been shown to substantially reduce foam volume, and also has the potential benefit of producing radiation-shielding foam tiles.Item Source Contaminant Control System Design, Operation, and Testing for the Trash Compaction and Processing System(2023 International Conference on Environmental Systems, 2023-07-16) Young, Janine; Pace, Gregory; Trieu, Serena; Martin, Kevin; Richardson, Tra-My Justine; Sepka, Steve; Parodi, JurekThe Trash Compaction and Processing System (TCPS) aims to reduce volume, biologically safen, physically stabilize, manage effluents, and recover resources from astronaut trash in the International Space Station (ISS). This process involves heating the trash to high temperatures, which in turn releases gaseous contaminants. Effluent management scenarios involve releasing these gases back to the ISS cabin after processing and/or directly venting these gases out to space via the Vacuum Exhaust System (VES). Concerns for recovering the gases back to cabin are crew health, safety, and spacecraft environmental impact. The Heat Melt Compactor (HMC) at NASA Ames Research Center (ARC) serves as a test system that supports TCPS development by conducting risk reduction activities associated with an ISS flight demonstration. Previous gas effluent studies were conducted on the HMC. The results consisted of contaminants from the trash exhaust to exceed Spacecraft Maximum Allowable Concentrations (SMAC), which are selected airborne contaminants that can elicit toxicity symptoms to crewmembers via exposure. The Source Contaminant Control System (SCCS) aims to reduce that risk by converting the contaminants into carbon dioxide (CO2) and water (H2O) vapor. The SCCS is composed of a carbon adsorbent bed, to avoid catalyst poisoning, and a catalytic oxidizer (CatOx), which promotes oxidation of the contaminants to CO2 and H2O. In turn, the gases coming out of the SCCS should be compatible to the ISS cabin and systems such as the Trace Contaminant Control System (TCCS). Preparation for SCCS testing alongside the HMC Gen 3 are currently underway at ARC. The main objectives are to evaluate CatOx efficiency by CO2 conversion and characterize effectiveness of removal by comparing contaminant results before and after CatOx. This paper will report on the SCCS design, operation, and testing with results.Item Space Mission Trash Processing Operational and Technical Limits(49th International Conference on Environmental Systems, 2019-07-07) Lee, Jeffrey; Martin, Kevin; Feller, Jeffrey; Pace, Gregory; Parodi, Jurek; Trieu, Serena; Kashani, Ali; Helvensteijn, BenTrash management is a critical logistic and life support function for future long duration missions. The Heat Melt Compactor (HMC) has been developed to examine the operational processes and technical limits for space mission trash processing and a new effort for developing and validating concepts for Trash Compaction and Processing Systems (TCPS) is currently underway. The HMC and TCPS examine four important functions when processing trash: trash volume reduction, trash biological safening, trash stabilization and effluent management of water and volatile organics. The requirements for space mission trash processing are non-trivial given the constraints of a confined crew cabin with stringent air quality standards, liquid/vapor phase separation under micro-gravity, biological growth in discarded foodstuff, and power and cooling limits. This paper describes the general requirements of a TCPS, touches upon Model Based Systems Engineering (MBSE) for modeling a TCPS, and notes lessons learned with the HMC.Item Technical Risks Associated with Heat Melt Compaction Systems(2020 International Conference on Environmental Systems, 2020-07-31) Lee, Jeffrey; Richardson, Tra-My Justine; Martin, Kevin; Young, Janine; Pace, Gregory; Parodi, Jurek; Trieu, Serena; Helvensteijn, Ben; Ewert, MichaelThe processing of trash and waste is a welcome and valuable addition to humans living and working in space. Besides the obvious desire to have a pleasant and productive habitation environment, trash management has many practical benefits for crew health, resource recovery, and volume reclamation through garbage compaction. The Trash Compaction and Processing System (TCPS), which is a NASA project to develop a trash processing system for long-duration spaceflight, is currently undergoing concept development with engineering prototype validation through two contracted efforts. The development efforts are being supported with activities associated with the NASA Generation 2 Heat Melt Compactor (HMC). The HMC is a facility that compacts trash, recovers water, heats the trash to eliminate biological activity, and manages gas and vapor effluents. The resulting residual processed trash is a compact tile that is free of biological growth and that can be used for augmenting radiation shields. The work being conducted with the HMC focuses on high risk technical areas with respect to operations, sub-system performance, and ISS effluent management interface requirements. This paper gives an overview of the technical risks and the current use of the HMC as a facility for reducing risk.Item The Trash Compaction Processing System (TCPS) Technology Demonstrations Science Objectives and Requirement Definitions(2023 International Conference on Environmental Systems, 2023-07-16) Richardson, Tra-My Justine; Lee, Jeffrey; Sepka, Steve; Martin, Kevin; Ewert, Michael; McKinley, Melissa; Trieu, Serena; Pace, Gregory; Young, Janine; White, DouglasThroughout the Next STEP Phase A and Phase B, the Trash Compaction Processing System (TCPS) is being developed for a technology demonstration on the International Space Station in 2025. For Phase A, two contractors built the proof-of-concept hardware. One contractor was chosen to build the TD hardware for Phase B. Both Phase A lesson learned and risk reduction activities at Ames Research Center were used to write the TD science objectives, scope, and requirements. The work at ARC aims to retire technical risks and provide design data to TCPS developers and the ISS system integrators. This paper will summarize the lessons learned from the proof-of-concept hardware and the risk reduction activities and how these lessons learned form the TD requirement matrix.Item Updated Effluent Analysis of the Heat Melt Compactor: Water Quality and Dewpoint Simulation of Gas Effluent(50th International Conference on Environmental Systems, 7/12/2021) Young, Janine; Parodi, Jurek; Trieu, Serena; Richardson, Tra-My Justine; Sepka, Steven; Lee, Jeffrey; Martin, Kevin; Pace, Gregory; Nadeau, Mary LouThe Trash Compaction and Processing System (TCPS) processes astronaut trash through volume reduction, biological safening, trash stabilization, effluent management, and resource recovery. TCPS development for the International Space Station (ISS) and risk reduction activities are supported by testing the Heat Melt Compactor (HMC) at NASA Ames Research Center (ARC). Processing trash extracts water vapor that can be recovered and releases volatile gases that must be managed. Part of the effluent is condensed and collected for analysis. The evaluation of the liquid effluent includes total organic carbon (TOC) concentrations, which provide a general indication of overall water quality, other defining characteristics such as pH and conductivity, and identified chemical components. On the other hand, the gas effluent may be recovered through a contaminant control system and vented to ISS cabin or vented overboard into space through the ISS Vacuum Exhaust System (VES). In the latter venting scenario, a constraint is the dewpoint of the gases disposed into the VES must be less than 15.5 oC. With simulations using Aspen Plus� and the HMC gas effluent results, flash calculations were conducted in the modeling study to calculate feed temperature and dewpoint at fixed pressures. Saturated vapor curves were also produced and provide a preliminary result on optimal feed conditions that satisfy the dewpoint and vapor-phase only requirements upon venting to VES. This paper serves as an update on the ongoing liquid and gas effluent analysis of the HMC/TCPS.