Browsing by Author "Alba, Richard"
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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 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 Shakedown Test of the Orbital Technologies PMWC for Performance in Treating Solid Wastes(45th International Conference on Environmental Systems, 2015-07-12) Wignarajah, Kanapathipillai; Alba, Richard; Fisher, John W.; Richardson, Tra-My JustineHeat melt compaction of space mission trash is a technology that has been under development by NASA for a number of years. Goals for heat melt compaction include compaction and volume reduction, recovery of water, disinfection of the wastes, prevention of growth of microbes (drying) in the wastes, control of contaminants in the effluent gases, and preparation of tiles for radiation shielding. A prototype heat melt compactor, the Plastic Melt Waste Compactor (PMWC), was delivered as part of a Small Business Innovative Research project by Orbital Technologies Corporation (Orbitec) to NASA Ames Research Center in June of 2014. Goals specific to the Orbitec PMWC development focused on chamber size, nonstick surface treatments, water recovery, and volume reduction. Although not an area of emphasis for the Orbitec PMWC development effort, disinfection is important in order to prevent microbial growth on trash tiles that are stored or used for radiation shielding from becoming a health hazard to the crew. This paper presents results of shakedown tests of the PMWC with a focus on the disinfection performance of the delivered hardware.