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In this work, two blends of isopropanol, n-butanol, and ethanol (IBE) that can be produced by metabolically engineered clostridium acetobutylicum are studied experimentally in advanced compression ignition (ACI). This is done to determine whether these fuel blends have the right fuel properties to enable thermally stratified compression ignition, a stratified ACI strategy that using the cooling potential of single stage ignition fuels to control the heat release process. The first microorganism, ATCC824, produces a blend of 34.5% isopropanol, 60.1% n-butanol, and 5.4% ethanol, by mass. The second microorganism, BKM19, produces a blend of 12.3% isopropanol, 54.0% n-butanol, and 33.7% ethanol, by mass. The sensitivity of both IBE blends to intake pressure, intake temperature, and cylinder energy content (fueling rate) is characterized and compared to that of its neat constituents. Both IBE blends behaved similarly with a reactivity level between that of ethanol and n-butanol.

Solid Oxide Electrolysis (SOE) with an embedded Sabatier reactor is an innovative and efficient concept for regenerative air revitalization. The concept safely eliminates handling of hydrogen, and works regardless of gravity and pressure environments with no moving parts and no multi-phase flows. It also is efficient because it requires no expendables from Earth while being compact with minimal impact on mass. The consequence is significant because SOE is an inherently suitable technology (and possibly the only technology) for enabling 100% oxygen regeneration from carbon dioxide and water vapor, two byproducts of crew activity that must be managed. To investigate the feasibility of this concept, a Sabatier reactor was successfully embedded into a single SOE cell.

An integrated water recovery system was operated for 91 days in support of the Lunar Mars Life Support Test Project (LMLSTP) Phase III test. The system combined both biological and physical-chemical processes to treat a combined wastewater stream consisting of waste hygiene water, urine, and humidity condensate. Biological processes were used for primary degradation of organic material as well as for nitrification of ammonium in the wastewater. Physical-chemical systems removed inorganic salts from the water and provided post-treatment. The integrated system provided potable water to the crew throughout the test. This paper describes the water recovery system and reviews the performance of the system during the test.

In a crewed spacecraft environment, atmospheric carbon dioxide (CO2) and moisture control are crucial. Hamilton Sundstrand has developed a stable and efficient amine-based CO2 and water vapor sorbent, SA9T, that is well suited for use in a spacecraft environment. The sorbent is efficiently packaged in pressure-swing regenerable beds that are thermally linked to improve removal efficiency and minimize vehicle thermal loads. Flows are controlled with a single spool valve. This technology has been baselined for the new Orion spacecraft, but additional data was needed on the operational characteristics of the package in a simulated spacecraft environment. One unit was tested with simulated metabolic loads in a closed chamber at Johnson Space Center during the latter part of 2006. Those test results were reported in a 2007 ICES paper.

Solid oxide electrolysis with embedded Sabatier reactors is being developed to regenerate all the oxygen required by a crew, eliminating any resupply needs. Metabolically produced carbon dioxide and water are electrolyzed at high temperature to produce pure dry oxygen. Carbon monoxide and hydrogen byproducts are converted to methane and water in the embedded Sabatier reactor. As it is embedded in the electrolyzer, the water is further electrolyzed to produce additional oxygen. A demonstration unit has been designed at full scale with a design production rate equivalent to that required to support one third of one person's oxygen requirements. Stack design was configured to enable the electrolyzer and Sabatier stacks to operate at their respective temperatures. Thermal modeling was performed to support internal heater sizing, insulation design, and evaluate touch temperatures. The unit was built and tested. Modeling and initial testing results are presented.

Thermal control systems for space application plant growth chambers offer unique challenges. The ability to control temperature and humidity independently gives greater flexibility for optimizing plant growth. Desired temperature and relative humidity range vary widely from 15°C to 35°C and 65% to 85% respectively. On top of all of these variables, the thermal control system must also be conservative in power and mass. These requirements to develop and test a robust thermal control system for space applications led to the design and development of the Environmental System Test Stand (ESTS) at NASA Johnson Space Center (JSC). The ESTS was designed to be a size constrained, environmental control system test stand with the flexibility to allow for a variety of thermal and lighting technologies. To give greater understanding to the environmental control system, the development of the ESTS included both mathematical models and the physical test stand.

The work presented in this paper summarizes the early results of an integrated advanced water recovery system test conducted by the Crew and Thermal Systems Division (CTSD) at NASA-Johnson Space Center (JSC). The system design and the results of the first two months of operation are presented. The overall objective of this test is to demonstrate the capability of an integrated advanced water recovery system to produce potable quality water for at least six months. Each subsystem is designed for operation in microgravity. The primary treatment system consists of a biological system for organic carbon and ammonia removal. Dissolved solids are removed by reverse osmosis and air evaporation systems. Finally, ion exchange technology in combination with photolysis or photocatalysis is used for polishing of the effluent water stream. The wastewater stream consists of urine and urine flush water, hygiene wastewater and a simulated humidity condensate.

The Major Constituent Analyzer (MCA) was activated on-orbit on 2/13/01 and provided essentially continuous readings of partial pressures for oxygen, nitrogen, carbon dioxide, methane, hydrogen and water in the ISS atmosphere. The MCA plays a crucial role in the operation of the Laboratory ECLSS and EVA operations from the airlock. This paper discusses the performance of the MCA as compared to specified accuracy requirements. The MCA has an on-board self-calibration capability and the frequency of this calibration could be relaxed with the level of instrument stability observed on-orbit. This paper also discusses anomalies the MCA experienced during the first year of on-orbit operation. Extensive Built In Test (BIT) and fault isolation capabilities proved to be invaluable in isolating the causes of anomalies. The process of fault isolation is discussed along with development of workaround solutions and implementation of permanent on-orbit corrections.

The International Space Station Waste Collector Subsystem Risk Mitigation Experiment (ISS WCS RME) was flown as the primary (Shuttle) WCS on Space Shuttle flight STS-104 (ISS-7A) in July 2001, to validate new design enhancements. In general, the WCS is utilized for collecting, storing, and compacting fecal & associated personal hygiene waste, in a zero gravity environment. In addition, the WCS collects and transfers urine to the Shuttle waste storage tank. All functions are executed while controlling odors and providing crew comfort. The ISS WCS previously flew on three Shuttle flights as the Extended Duration Orbiter (EDO) WCS, as it was originally designed to support extended duration Space Shuttle flights up to 30 days in length. Soon after its third flight, the Space Shuttle Program decided to no longer require 30 day extended mission duration capability and provided the EDO WCS to the ISS Program.

Two crops of lettuce (Lactuca sativa cv. Waldmann's Green) were grown in the Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center. The RLSS Test Bed is an atmospherically closed, controlled environment facility for the evaluation of regenerative life support systems using higher plants. The chamber encloses 10.6 m2 of growth area under cool-white fluorescent lamps. Lettuce was double seeded in 480 pots, each containing about 250 cm3 of calcined-clay substrate. Each pot was irrigated with half-strength Hoagland's nutrient solution at an average total applied amount of 2.5 and 1.8 liters pot-1, respectively, over each of the two 30-day crop tests. Average environmental and cultural conditions during both tests were 23°C air temperature, 72% relative humidity, 1000 ppm carbon dioxide (CO2), 16h light/8h dark photoperiod, and 356 μmol m-2s-1 photosynthetic photon flux.

Approximately 50% of the water consumed by International Space Station crewmembers is water recovered from cabin humidity condensate. Condensing heat exchangers in the Russian Service Module (SM) and the United States On-Orbit Segment (USOS) are used to control cabin humidity levels. In the SM, humidity condensate flows directly from the heat exchanger to a water recovery system. In the USOS, a metal bellows tank located in the US Laboratory Module (LAB) collects and stores condensate, which is periodically off-loaded in about 20-liter batches to Contingency Water Containers (CWCs). The CWCs can then be transferred to the SM and connected to a Condensate Feed Unit that pumps the condensate from the CWCs into the water recovery system for processing. Samples of the condensate in the tank are collected during the off-loads and returned to Earth for analyses.

The Shuttle Orbiter humidity control and carbon dioxide removal system for extended duration missions presently uses a solid amine called HS-C. This August, on board STS-62, a new solid amine called HS-C+ will be used. HS-C+ uses the same amine and the substrate material, but a different preparation process. Forty-seven breakthrough tests have been conducted to characterize the performance of HS-C+. CO2 partial pressure, bed temperature, and H2O partial pressure were varied. Eleven HS-C breakthrough tests were also run to provide a direct comparison. Under all conditions tested, HS-C+ outperformed HS-C. Both materials adsorb all CO2 and H2O available at the start of a test when the beds are fully desorbed. As the bed becomes partially loaded, the CO2 and H2O adsorption rates decrease rapidly. HS-C+ continues adsorbing all CO2 and H2O available for a longer time. Greater surface area on HS-C+ may cause the improved performance.

The Space Shuttle humidity separator prefilter was developed to remove debris from the air/water stream that flows from the cabin condensing heat exchanger to the humidity separator. Debris in this flow stream has caused humidity separator pitot tube clogging and subsequent water carryover on several Shuttle flights. The first design concept of the prefilter was flown on STS-40 in June, 1991. The prefilter was installed on-orbit. Video footage of its operation revealed that the prefilter did not pass water at a constant rate, resulting in a tendency to slug the humidity separator. The results from this flight test have resulted in a complete redesign of the prefilter. In this paper the first prefilter design is described, the flight results from STS-40 are examined, and the on-orbit performance of the prefilter is explained. The redesigned prefilter is described with emphasis on the features that should allow successful reduced gravity operation.

On the International Space Station (ISS), humidity condensate will be collected from the atmosphere and treated by multifiltration to produce potable water for use by the crews. Ground-based development tests have demonstrated that multifiltration beds filled with a series of ion-exchange resins and activated carbons can remove many inorganic and organic contaminants effectively from wastewaters. As a precursor to the use of this technology on the ISS, a demonstration of multifiltration treatment under microgravity conditions was undertaken. On the Space Shuttle, humidity condensate from cabin air is recovered in the atmosphere revitalization system, then stored and periodically vented to space vacuum. A Shuttle Condensate Adsorption Device (SCAD) containing sorbent materials similar to those planned for use on the ISS was developed and flown on STS-68 as a continuation of DSO 317, which was flown initially on STS-45 and STS-47.

In a crewed spacecraft environment, atmospheric carbon dioxide (CO2) and moisture control are crucial. Hamilton Sundstrand has developed a stable and efficient amine-based CO2 and water vapor sorbent, SA9T, that is well suited for use in a spacecraft environment. The sorbent is efficiently packaged in pressure-swing regenerable beds that are thermally linked to improve removal efficiency and minimize vehicle thermal loads. Flows are all controlled with a single spool valve. This technology has been baselined for the new Orion spacecraft. However, more data was needed on the operational characteristics of the package in a simulated spacecraft environment. A unit was therefore tested with simulated metabolic loads in a closed chamber at Johnson Space Center during the last third of 2006. Tests were run at a variety of cabin temperatures and with a range of operating conditions varying cycle time, vacuum pressure, air flow rate, and crew activity levels.

Regenerative-type subsystems are being tested at JSC to provide atmosphere revitalization functions of oxygen supply and carbon dioxide (CO2) removal for a future Space Station. Oxygen is supplied by an electrolysis subsystem, developed by General Electric, Wilmington, Mass., which uses the product water from either the CO2 reduction subsystem or a water reclamation process. CO2 is removed and concentrated by an electrochemical process, developed by Life Systems, Inc., Cleveland, Ohio. The concentrated CO2 is reduced in a Sabatier process with the hydrogen from the electrolysis process to water and methane. This subsystem is developed by Hamilton Standard, Windsor Locks, Conn. These subsystems are being integrated into an atmosphere revitalization group. This paper describes the integrated test configuration and the initial checkout test. The feasibility and design compatibility of these subsystems integrated into an air revitalization system is discussed.

This paper describes the development of a membrane-based dehumidification process for space-based applications, such as spacecraft cabins and extra-vehicular-activity (EVA) space suits. Results presented are from 1) screening tests conducted to determine the efficacy of various membranes to separate water vapor from air, and 2) parametric and long-term tests of membranes operated at conditions that simulate the range of environmental conditions (e.g., temperature and relative humidity [RH]) expected in the planned space station. Also included in this paper is a discussion of preliminary designs of membrane-based dehumidification processes for the space station and EVA space suits. These designs result in compact and energy-efficient systems that offer significant advantages over conventional dehumidification processes.

Reduction of metabolic carbon dioxide is one of the essential steps in physiochemical air revitalization for long-duration manned space missions. Under contract with NASA Johnson Space Center, Hamilton Standard is developing an Advanced Carbon Reactor Subsystem (ACRS) to produce water and dense solid carbon from carbon dioxide and hydrogen. The ACRS essentially consists of a Sabatier Methanation Reactor (SMR) to reduce carbon dioxide with hydrogen to methane and water, a gas-liquid separator to remove product water from the methane, and a Carbon Formation Reactor (CFR) to pyrolyze methane to carbon and hydrogen. The hydrogen is recycled to the SMR, while the produce carbon is periodically removed from the CFR. The SMR is well-developed, while the CFR is under development. In this paper, the fundamentals of the SMR and CFR processes are presented and results of Breadboard CFR testing are reported.

Twenty-nine recycled water, eight stored (ground-supplied) water, and twenty-eight humidity condensate samples were collected on board the Mir Space Station during the Phase One Program (1995-1998). These samples were analyzed to determine potability of the recycled and ground-supplied water, to support the development of water quality monitoring procedures and standards, and to assist in the development of water reclamation hardware. This paper describes and summarizes the results of these analyses and lists the lessons learned from this project. Results show that the recycled water and stored water on board Mir, in general, met NASA, Russian Space Agency (RSA), and U.S. Environmental Protection Agency (EPA) standards.

An experimental study was conducted on a Ricardo Hydra single-cylinder light-duty diesel research engine. Start of Injection (SOI) timing sweeps from -350 deg aTDC to -210 deg aTDC were performed on a total number of five pistons including two baseline metal pistons and three coated pistons to investigate the effects of thick thermal barrier coatings (TBCs) on the efficiency and emissions of low-temperature combustion (LTC). A fuel with a high latent heat of vaporization, wet ethanol, was chosen to eliminate the undesired effects of thick TBCs on volumetric efficiency. Additionally, the higher surface temperatures of the TBCs can be used to help vaporize the high heat of vaporization fuel and avoid excessive wall wetting. A specialized injector with a 60° included angle was used to target the fuel spray at the surface of the coated piston.