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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Membrane-Based Water Evaporator for a Space Suit

A membrane-based water evaporator has been developed that is intended to serve as a heat-rejection device for a space suit. This evaporator would replace the current sublimator that is sensitive to contamination of its feedwater. The design of the membrane-based evaporator takes advantage of recent advances in hydrophobic micropore membranes to provide robust heat rejection with much less sensitivity to contamination. The low contamination sensitivity allows use of the heat transport loop as feedwater, eliminating the need for the separate feedwater system used for the sublimator. A cross section of the evaporator is shown in the accompanying figure. The space-suit cooling loop water flows into a distribution plenum, through a narrow annulus lined on both sides with a hydrophobic membrane, into an exit plenum, and returns to the space suit. Two perforated metal tubes encase the membranes and provide structural strength. Evaporation at the membrane inner surface dissipates the waste heat from the space suit. The water vapor passes through the membrane, into a steam duct and is vented to the vacuum environment through a back-pressure valve. The back-pressure setting can be adjusted to regulate the heat-rejection rate and the water outlet temperature.

Ungar, Eugene K.↗
NASA NTRS1981

A MHD channel study for the ETF conceptual design

The procedures and computations used to identify an MHD channel for a 540 mW(I) EFT-scale plant are presented. Under the assumed constraints of maximum E(x), E(y), J(y) and Beta; results show the best plant performance is obtained for active length, L is approximately 12 M, whereas in the initial ETF studies, L is approximately 16 M. As MHD channel length is reduced from 16 M, the channel enthalpy extraction falls off, slowly. This tends to reduce the MHD power output; however, the shorter channels result in lower heat losses to the MHD channel cooling water which allows for the incorporation of more low pressure boiler feedwater heaters into the system and an increase in steam plant efficiency. The net result of these changes is a net increase in the over all MHD/steam plant efficiency. In addition to the sensitivity of various channel parameters, the trade-offs between the level of oxygen enrichment and the electrical stress on the channel are also discussed.

Wang, S. Y.↗
NASA NTRSDate not supplied

Exploration Portable Life Support System Hatch Component Design

The design for the Exploration Extravehicular Mobility Unit (xEMU) is continuously being developed and many previous gaps in technologies have begun initial development. Various Exploration Portable Life Support System (xPLSS) Hatch components had been at a stall in technology development for many years including the Feedwater Supply Assembly, Trace Contaminant Control System, and the thermal loop filters. The challenging requirements and initial design of these components were previously discussed in “Exploration Portable Life Support System Hatch Component Design Challenges and Progress”. NASA has plans to go back to the Moon. The development of each of these components is relevant not only to the xEMU, but also to the International Space Station, Gateway, and commercial space businesses. As the xPLSS is being designed, built, integrated, and tested at the NASA Johnson Space Center, technology solutions will have a direct incorporation path as the xPLSS is matured to meet design and performance goals. This is a follow on paper to discuss the initial implementation of the hatch component designs, changes due to existing challenges, and performance results of these components as the xEMU project completes the first phase of towards flight, known as Design Verification Test (DVT).

Kristina Todd↗
NASA NTRS2009

X-38 Advanced Sublimator

A document discusses a heat rejection device for transferring heat from a space vehicle by venting water into space through the use of a novel, two-stage water distribution system. The system consists of two different, porous media that stop water-borne contaminants from clogging the system and causing operational failures. Feedwater passes through a small nozzle, then into a porous disk made of sintered stainless steel, and then finally into large-pore aluminum foam. The smaller pore layer of the steel disk controls the pressure drop of the feedwater. The ice forms in the foam layer, and then sublimates, leaving any contaminants behind. The pore-size of the foam is two orders of magnitude larger than the current porous plate sublimators, allowing for a greater tolerance for contaminants. Using metallic fibers in the foam also negates problems with compression seen in the use of poly(tetrafluoroethylene) felt.

Dingell, Chuck↗
NASA NTRS1976

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 7: Metal vapor Rankine topping-steam bottoming cycles

Adding a metal vapor Rankine topper to a steam cycle was studied as a way to increase the mean temperature at which heat is added to the cycle to raise the efficiency of an electric power plant. Potassium and cesium topping fluids were considered. Pressurized fluidized bed or pressurized (with an integrated low-Btu gasifier) boilers were assumed. Included in the cycles was a pressurizing gas turbine with its associated recuperator, and a gas economizer and feedwater heater. One of the ternary systems studied shows plant efficiency of 42.3% with a plant capitalization of $66.7/kW and a cost of electricity of 8.19 mills/MJ (29.5 mills/kWh).

Deegan, P. B.↗
NASA NTRS1979

A fundamental study of liquid spray evaporation at a heated surface

The influence of feedwater temperature and the influence of pulsing nozzle flow on the heat transfer characteristics in the spray evaporative cooling process were investigated. A commercial water circulation heater was installed in the feedwater line between the supply reservoir and the nozzle. A pass through the heater provided water at temperatures up to 50 C at the nozzle; higher temperatures were obtained by multiple heater passes. A thermocouple installed in the water line just upstream of the nozzle provided a measure of the feedwater temperature. Initial tests were run with belljar exhaust orifice number two which provided a pressure in a range about 7mm Hg abs. The feedwater temperature was heated to a temperature of 45 C. Results indicate that for a given system operating pressure, there is an upper limit on the feedwater temperature above which the spray will flash to vapor before hitting the surface to be cooled.

Wierum, F. A.↗
NASA NTRS1985

Space shuttle revitalization system

The Space Shuttle air revitalization system is discussed. The sequential steps in loop closure are examined and a schematic outline of the regenerative air revitalization system is presented. Carbon dioxide reduction subsystem concepts are compared. Schemes are drawn for: static feedwater electrolysis cell, solid polymer electrolyte water electrolysis cell, air revitalization system, nitrogen generation reactions, nitrogen subsystem staging, vapor compression distillation subsystem, thermoelectric integrated membrane evaporation subsystem, catalytic distillation water reclamation subsystem, and space shuttle solid waste management system.

Quattrone, P. D.↗
NASA NTRS2022

Ultra-Pure, High Endurance Liquid Bladder with Volume Sensor for Space Applications

The NASA Portable Life Support System (PLSS) for the Exploration Extravehicular Mobility Unit (xEMU) incorporates a Feedwater Supply Assembly (FSA) to store consumable cooling water. The FSA accepts pure water prior to each Extra-Vehicular Activity (EVA), then supplies this water to a membrane evaporator at ambient suit pressure during the eight hour EVA. The FSA must function reliably for hundreds of EVAs over 15 years of service without introducing contamination that may accumulate and foul the membrane. We present a unique design that combines the benefits of a flexible fluoropolymer bladder with the strength and convenience of a rigid tank, providing an ultra-pure, ambient-pressure reservoir with fill-drain cycle life exceeding 3000, internal pressure tolerance exceeding 100 psi, high volumetric efficiency, near-zero dead volume, optical transparency for visual inspection, simplified mounting, and very low mass. We also incorporate a novel volume sensor suitable for both microgravity and arbitrarily accelerated environments and capable of real-time monitoring with accuracy on the order of 2.5% full scale. Analytical predictions are supported by experimental test data from a mature subscale prototype.

PLSS Portable Life Support System FSA Feedwater Su↗
NASA NTRS2024

Short Exploration Extravehicular Mobility Unit Testing Setup: Evaluation Under Realistic Pressure and Thermal Conditions

The purpose of Short Exploration Extravehicular Mobility Unit (SxEMU) thermal vacuum testing was to verify the functionality of the Design Verification Testing (DVT) prototype xEMU (SxEMU for this test) at vacuum pressures and extreme space and lunar surface temperature conditions. The SxEMU Thermal Vacuum Test was the culmination of the DVT xEMU project. This paper’s focus is on the pre-Extravehicular Activity (EVA) test setup, and general performance of the SxEMU Portable Life Support Subsystem (xPLSS), with focus on the performance of the Primary Oxygen Assembly (POA) and Secondary Oxygen Assembly (SOA), including Secondary Oxygen Regulator (SOR) takeover and the POA and SOA low-setpoint change inhibit. The initial pre-EVA test preparation included recharging the batteries and replenishing consumables, including test-system water, oxygen assemblies (with gaseous nitrogen), and the integrated thermal loops, including the Feedwater Supply Assemblies. xPLSS functionality testing included carbon dioxide (CO2) removal via the Rapid Cycle Amine swingbed system, thermal loop temperature control, and monitoring of suit ventilation loop pressure, temperature, and CO2 percentages. Testing evaluated automatic takeover of suit pressure control by the SOR after the primary oxygen supply is depleted. The Primary Oxygen Regulator and SOR low-setpoint change inhibit function prevents the crewmember from inadvertently setting the primary regulator to a low pressure setpoint during an EVA.

xPLSS↗
NASA NTRS2008

International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Erickson, Robert J.↗
NASA NTRS2010

Three Years of on Orbit ISS Oxygen Generation System Operation 2007-2010

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) has accumulated 240 days of continuous operation at varied oxygen production rates within the US Laboratory Module (LAB) since it was first activated in July 2007. OGS relocated from the ISS LAB to Node 3 during 20A Flight (February 2010). The OGS rack delivery was accelerated for on-orbit checkout in the LAB, and it was launched to ISS in July of 2006. During the on-orbit checkout interval within the LAB from July 2007 to October 2008, OGS operational times were limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Longer runtimes are now achievable due to the continuous feedwater availability after ULF2 delivery and activation of the USOS Water Recovery System (WRS) racks. OGS is considered a critical function to maintaining six crew capability. There have been a number of failures which interrupted or threatened to interrupt oxygen production. Filters in the recirculation loop have clogged and have been replaced, Hydrogen sensors have fallen out of specifications, a pump delta pressure sensor failed, a pump failed to start, and the voltage on the cell stack increased out of tolerance. This paper will discuss the operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Diderich, Greg S.↗
NASA NTRS2017

Development Specification for the Feedwater Supply Assembly (FSA), FSA-431 with Integrated Auxiliary Feedwater Supply Assembly (AFSA), FSA-531

The FSA with Integrated Aux FSA Specification establishes the requirements for design, performance, and testing of the FSA-431/FSA-531 assembly in compliance with CTSD-ADV-780, Development Specification for the Advanced EMU (AEMU) Portable Life Support System (PLSS). This section contains the technical design and performance requirements for the integrated assembly of the Feedwater Supply Assembly and Auxiliary Feedwater Supply Assembly for the Advanced EVA Development Portable Life Support Subsystem (PLSS).

Anchondo, Ian↗
NASA NTRS1990

Reexamination of METMAN, Recommendations on Enhancement of LCVG, and Development of New Concepts for EMU Heat Sink

METMAN is a 41-node transient metabolic computer code developed in 1970 and revised in 1989 by Lockheed Engineering and Sciences, Inc. This program relies on a mathematical model to predict the transient temperature distribution in a body influenced by metabolic heat generation and thermal interaction with the environment. A more complex 315-node model is also available that not only simulates the thermal response of a body exposed to a warm environment, but is also capable of describing the thermal response resulting from exposure to a cold environment. It is important to compare the two models for the prediction of the body's thermal response to metabolic heat generation and exposure to various environmental conditions. Discrepancies between the twi models may warrant an investigation of METMAN to ensure its validity for describing the body's thermal response in space environment. The Liquid Cooling and Ventilation Garment is a subsystem of the Extravehicular Mobility Unit (EMU). This garment, worn under the pressure suit, contains the liquid cooling tubing and gas ventilation manifolds; its purpose is to alleviate or reduce thermal stress resulting from metabolic heat generation. There is renewed interest in modifying this garment through identification of the locus of maximum heat transfer at body-liquid cooled tubing interface. The sublimator is a vital component of the Primary Life Support System (PLSS) in the EMU. It acts as a heat sink to remove heat and humidity from the gas ventilating circuit and the liquid cooling loop of the LCVG. The deficiency of the sublimator is that the ice, used as the heat sink, sublimates into space. There is an effort to minimize water losses in the feedwater circuit of the EMU. This requires developing new concepts to design an alternative heat sink system. Efforts are directed to review and verify the heat transfer formulation of the analytical model employed by METMAN. A conceptual investigation of regenerative non-venting heat-sink subsystem for the EMU is recommended.

Karimi, Amir↗
NASA NTRSDate not supplied

SERFE Water Quality Results

NASA has been developing a new spacesuit, called the Exploration Extravehicular Mobility Unit (xEMU) for over a decade. This spacesuit is underdevelopment to support missions to the International Space Station (ISS) and also to the Moon. Improvements in the life and robustness of the Portable Life Support System (PLSS) has been a major objective of these efforts. Water quality, and how that impacts the performance of the life support system hardware, are areas where improvements could greatly help to achieve these goals. The Suit Water Membrane Evaporator (SWME) was chosen as the technology to provide cooling to the xEMU and has undergone several iterations of development over this period. An ISS flight experiment centered around the SWME and other thermal loop technologies was developed and has been under test in an ISS EXpedite PRocessing of Experiments to the Space Station (EXPRESS) rack since November of 2020. In addition to the SWME, The SWME EXPRESS Rack Flight Experiment (SERFE) contains several technology demonstrations from the xEMU project and has been demonstrating their performance in micro-gravity and over an extended duration. This paper will summarize the results of the water quality analysis performed to date throughout the SERFE testing program. Special care was taken to select materials, process hardware, and control the quality of the feedwater used in SERFE testing so that it would be representative of a thermal control system that could be used on a spacesuit for a lunar mission. In addition, the testing schedule, including periods of quiescence in between tests, was also selected to simulate a real mission profile in ways that would be critical to water quality. Results include data and analysis on microbial activity, biocidal iodine, metals, organic carbon, and several other customary indicators of water quality in an operational system. Testing spans over a year and a half of wetted life of the SERFE Flight Unit and the SERFE Ground Unit.

Colin Campbell↗
NASA NTRS2009

Investigation of Transient Performance for a Sublimator

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100%. However, sublimators are currently being considered to operate in a cyclical topping mode during low lunar orbit for Altair and possibly Orion, which represents a new mode of operation for sublimators. In this mission phase, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization during various feedwater timing scenarios. The X-38 sublimator, which represents the state of the art in sublimator technology, was used to understand this behavior and to quantify the feedwater performance. Data from various scenarios will be analyzed to investigate feedwater utilization under the cyclical conditions. This paper will also provide recommendations for future sublimator designs and/or feedwater control.

Leimkuehler, Thomas O.↗
NASA NTRS1979

Conceptual design of thermal energy storage systems for near term electric utility applications

Potential concepts for near term electric utility applications were identified. The most promising ones for conceptual design were evaluated for their economic feasibility and cost benefits. The screening process resulted in selecting two coal-fired and two nuclear plants for detailed conceptual design. The coal plants utilized peaking turbines and the nuclear plants varied the feedwater extraction to change power output. It was shown that the performance and costs of even the best of these systems could not compete in near term utility applications with cycling coal plants and typical gas turbines available for peaking power. Lower electricity costs, greater flexibility of operation, and other benefits can be provided by cycling coal plants for greater than 1500 hours of peaking or by gas turbines for less than 1500 hours if oil is available and its cost does not increase significantly.

Hall, E. W.↗
NASA NTRS2010

Investigation of Transient Performance for a Sublimator

Sublimators have been used as heat rejection devices for a variety of space applications including the Apollo Lunar Module and the Extravehicular Mobility Unit (EMU). Sublimators typically operate with steady-state feedwater utilization at or near 100 %. However, Sublimators are currently being considered to operate in a cyclical topping mode during low lunar orbit for Altair and possibly Orion. The cyclical topping mode represents a new mode of operation for sublimators. In this operational mode, the sublimator will be repeatedly started and stopped during each orbit to provide supplemental heat rejection for the portion of the orbit where the radiative sink temperature exceeds the system setpoint temperature. This paper will investigate the effects of these transient starts and stops on the feedwater utilization for various feedwater timing scenarios.

Sheth, Rubik B.↗