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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Sample Delivery and Computer Control Systems for Detecting Leaks in the Main Engines of the Space Shuttle

The main engines of the Space Shuttle use hydrogen and oxygen as the fuel and oxidant. The explosive and fire hazards associated with these two components pose a serious danger to personnel and equipment. Therefore prior to use the main engines undergo extensive leak tests. Instead of using hazardous gases there tests utilize helium as the tracer element. This results in a need to monitor helium in the ppm level continuously for hours. The major challenge in developing such a low level gas monitor is the sample delivery system. This paper discuss a system developed to meet the requirements while also being mobile. Also shown is the calibration technique, stability, and accuracy results for the system.

Griffin, Timothy P.↗
NASA NTRS2001

Detection of Micro-Leaks Through Complex Geometries Under Mechanical Load and at Cryogenic Temperature

Polymer Matrix Composite (PMC) hydrogen tanks have been proposed as an enabling technology for reducing the weight of Single-Stage-to-Orbit reusable launch vehicles where structural mass has a large impact on vehicle performance. A key development issue of these lightweight structures is the leakage of hydrogen through the composite material. The rate of hydrogen leakage can be a function of the material used, method of 6 fabrication used to manufacture the tank, mechanical load the tank must react, internal damage-state of the material, and the temperatures at which the tank must operate. A method for measuring leakage through a geometrically complex structure at cryogenic temperature and under mechanical load was developed, calibrated and used to measure hydrogen leakage through complex X-33 liquid-hydrogen tank structure sections.

Rivers, H. Kevin↗
DOE OSTI2025

Seismic H2: Version 1.0

Seismic-H2 is an integrated software package for geological hydrogen reservoir simulation, optimization, and leakage monitoring. The package includes multiple components: (1) code used for modeling seismic wave propagation in 3D heterogeneous elastic media based on finite-difference method to support detection of geological hydrogen storage reservoir leakage; (2) 3D reservoir simulations of leaks from an underground reservoir and 3D simulations of saline aquifers and depleted gas reservoirs; (3) seismic monitoring costs of passive and active seismic monitoring required for UHS; (4) rock physics calculations and interpolations for converting the reservoir simulations from part (2) into the elastic media models in part (1); (5) pre-processing seismic data; and lastly (6), a GUI interface that combines these different components.

Creasy, Neala↗
NASA NTRS2013

Autonomous Cryogenic Leak Detector for Improving Launch Site Operations

NASA, military, and commercial satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. This project has developed a tapered optical fiber sensor for detecting hydrogen. The invention involves incorporating chemical indicators on the tapered end of an optical fiber using organically modified silicate nanomaterials. The Hazardous Gas Detection Lab (HGDL) at Kennedy Space Center is involved in the design and development of instrumentation that can detect and qualify various mission-critical chemicals. Historically, hydrogen, helium, nitrogen, oxygen, and argon are the first five gases of HGDL focus. The use of these cryogenic fluids in the area of propulsion offers challenges. Due to their extreme low temperatures, these fluids induce contraction of the materials they contact, a potential cause of leakage. Among them, hydrogen is of particular concern. Small sensors are needed in multiple locations without adding to the structural weight. The most vulnerable parts of the engine are the connection flanges on the transfer lines, which have to support cycles of large thermal amplitude. The thermal protection of the engine provides a closed area, increasing the likelihood of an explosive atmosphere. Thus, even a small leak represents an unacceptable hazardous condition during loading operations, in flight, or after an aborted launch. Tapered fibers were first fabricated from 1/1.3-mm core/cladding (silica/ plastic) optical fibers. Typically a 1-ft (approx. 30- cm) section of the 1-mm fiber is cut from the bundle and marked with a pen into five 2-.-in. (.5.7-cm) sections. A propane torch is applied at every alternate mark to burn the jacket and soften the glass core. While the core is softening, the two ends of the fiber are pulled apart slowly to create fine tapers of .- to .-in. (.6- to 12-mm) long on the 1-mm optical fiber. Following this, the non-tapered ends of the fibers are polished to a 0.3-micron finish. Then these fibers were coated with indicators sensitive to hydrogen. The tapered hydrogen detection system with its unique flexibility is the only system that can be placed in many locations inside the vehicles and detect the exact location of leaks, saving millions of dollars for launch vehicle industries.

Goswami, Kisholoy↗
NASA NTRSDate not supplied

Exploring the Potential of Hydrogen as a Lift Gas for Nasa’s Scientific Balloon Program

The United States National Aeronautics and Space Administration (NASA) Balloon Program has a rich history of conducting scientific research in the stratosphere, offering a unique platform for experiments in the near-space environment. One critical component of these high-altitude balloons is the choice of lift gas, which is pivotal to achieving the desired altitude and, thus, mission objectives. Traditionally, helium has been the preferred lift gas due to its inert properties and safety considerations. However, the increasing demand and limited global helium reserves have prompted NASA to explore alternative lift gases, with hydrogen emerging as the most logical choice. Hydrogen boasts several advantages, including its abundant availability, cost-effectiveness, and enhanced lift capability compared to helium. Moreover, it can support a wide range of scientific payloads, enabling extended mission durations and increased payload capacities, ultimately strengthening the program’s scientific potential. However, adopting hydrogen as a lift gas is not without challenges. Safety concerns, especially during the launch and recovery phases, are paramount. NASA and the other major players in the scientific ballooning community have been developing stringent safety protocols and engineering solutions to mitigate these risks. This development includes specialized support systems, leak detection mechanisms, and enhanced launch and recovery procedures. Additionally, environmental considerations must be carefully evaluated. Hydrogen release has the potential to increase concentrations of various greenhouse gases, and its usage must be balanced against the benefits it offers to scientific research and exploration. This paper delves into the ongoing research and development efforts to ensure balloon-based research’s long-term sustainability and its ability to continue pushing the boundaries of scientific discovery. This research demonstrates NASA’s commitment to innovation, safety, and environmental responsibility while maintaining its mission to advance our understanding of the Earth and the cosmos.

balloon↗
NASA NTRS2006

Infrared Instrument for Detecting Hydrogen Fires

The figure shows an instrument incorporating an infrared camera for detecting small hydrogen fires. The instrument has been developed as an improved replacement for prior infrared and ultraviolet instruments used to detect hydrogen fires. The need for this or any such instrument arises because hydrogen fires (e.g., those associated with leaks from tanks, valves, and ducts) pose a great danger, yet they emit so little visible light that they are mostly undetectable by the unaided human eye. The main performance advantage offered by the present instrument over prior hydrogen-fire-detecting instruments lies in its greater ability to avoid false alarms by discriminating against reflected infrared light, including that originating in (1) the Sun, (2) welding torches, and (3) deliberately ignited hydrogen flames (e.g., ullage-burn-off flames) that are nearby but outside the field of view intended to be monitored by the instrument. Like prior such instruments, this instrument is based mostly on the principle of detecting infrared emission above a threshold level. However, in addition, this instrument utilizes information on the spatial distribution of infrared light from a source that it detects. Because the combination of spatial and threshold information about a flame tends to constitute a unique signature that differs from that of reflected infrared light originating in a source not in the field of view, the incidence of false alarms is reduced substantially below that of related prior threshold- based instruments.

Youngquist, Robert↗
NASA NTRS2010

SSV Launch Monitoring Strategies: HGDS Design Implementation Through System Maturity

With over 500,000 gallons of liquid hydrogen and liquid oxygen, it is of vital importance to monitor the space shuttle vehicle (SSV) from external tank (ET) load through launch. The Hazardous Gas Detection System (HGDS) was installed as the primary system responsible for monitoring fuel leaks within the orbiter and ET. The HGDS was designed to obtain the lowest possible detection limits with the best resolution while monitoring the SSV for any hydrogen, helium, oxygen, or argon as the main requirement. The HGDS is a redundant mass spectrometer used for real-time monitoring during Power Reactant Storage and Distribution (PRSD) load and ET load through launch or scrub. This system also performs SSV processing leak checks of the Tail Service Mast (TSM) umbilical quick disconnects (QD's), Ground Umbilical Carrier Plate (GUCP) QD's and supports auxiliary power unit (APU) system tests. From design to initial implementation and operations, the HGDS has evolved into a mature and reliable launch support system. This paper will discuss the operational challenges and lessons learned from facing design deficiencies, validation and maintenance efforts, life cycle issues, and evolving requirements

Shoemaker, Marc D.↗
DOE OSTI2020

Development of risk mitigation guidance for sensor placement inside mechanically ventilated enclosures – Phase 1

Guidance on Sensor Placement was identified as the top research priority for hydrogen sensors at the 2018 HySafe Research Priority Workshop on hydrogen safety in the category Mitigation, Sensors, Hazard Prevention, and Risk Reduction. This paper discusses the initial steps (Phase 1) to develop such guidance for mechanically ventilated enclosures. This work was initiated as an international collaborative effort to respond to emerging market needs related to the design and deployment equipment for hydrogen infrastructure that is often installed in individual equipment cabinets or ventilated enclosures. The ultimate objective of this effort is to develop guidance for an optimal sensor placement such that, when integrated into a facility design and operation, will allow earlier detection at lower levels of incipient leaks, leading to significant hazard reduction. Reliable and consistent early warning of hydrogen leaks will allow for the risk mitigation by reducing or even eliminating the probability of escalation of small leaks into large and uncontrolled events. To address this issue, a study of a real-world mechanically ventilated enclosure containing GH2 equipment was conducted, where CFD modeling of the hydrogen dispersion (performed by AVT and UQTR, and independently by the JRC) was validated by the NREL Sensor laboratory using a Hydrogen Wide Area Monitor (HyWAM) consisting of a 10-point gas and temperature measurement analyzer. In the release test, helium was used as a hydrogen surrogate. Expansion of indoor releases to other larger facilities (including parking structures, vehicle maintenance facilities and potentially tunnels) and incorporation into QRA tools, such as HyRAM is planned for Phase 2. It is anticipated that results of this work will be used to inform national and international standards such as NFPA 2 Hydrogen Technologies Code, Canadian Hydrogen Installation Code (CHIC) and relevant ISO/TC 197 and CEN documents.

08 HYDROGEN↗
NASA NTRS2016

Technology Development for Hydrogen Propellant Storage and Transfer at the Kennedy Space Center (KSC)

The National Aeronautics and Space Administration (NASA) is a major user of liquid hydrogen. In particular, NASA's John F. Kennedy (KSC) Space Center has operated facilities for handling and storing very large quantities of liquid hydrogen (LH2) since the early 1960s. Safe operations pose unique challenges and as a result NASA has invested in technology development to improve operational efficiency and safety. This paper reviews recent innovations including methods of leak and fire detection and aspects of large storage tank health and integrity. We also discuss the use of liquid hydrogen in space and issues we are addressing to ensure safe and efficient operations should hydrogen be used as a propellant derived from in-situ volatiles.

cryogenics↗
NASA NTRS2001

A Quadrupole Ion Trap Mass Spectrometer for Quantitative Analysis of Nitrogen-Purged Compartments within the Space Shuttle

To enter orbit, the Space Shuttle burns 1.8 million liters of liquid hydrogen combined with 0.8 million liters of liquid oxygen through three rocket engines mounted in the aft. NASA monitors the nitrogen-purged aft compartment for increased levels of hydrogen or oxygen in order to detect and determine the severity of a cryogenic fuel leak. Current monitoring is accomplished with a group of mass spectrometer systems located as much as 400 feet away from the Shuttle. It can take up to 45 seconds for gas to reach the mass spectrometer, which precludes monitoring for leaks in the final moments before liftoff (the orbiter engines are started at T-00:06 seconds). To remedy the situation, NASA is developing a small rugged mass spectrometer to be used as point-sensors around the Space Shuttle. As part of this project, numerous mass analyzer technologies are being investigated. Presented here are the preliminary results for one such technology, quadrupole ion trap mass spectrometry (QITMS). A compact QITMS system has been developed in-house at the University of Florida for monitoring trace levels of four primary gases, hydrogen, helium, oxygen, and argon, all in a nitrogen background. Since commercially available QITMS systems are incapable of mass analysis at m/z(exp 2), the home-built system is preferred for the evaluation of QITMS technology.

Ottens, Andrew K.↗
NASA NTRS1999

Propellant Feed System Leak Detection: Lessons Learned From the Linear Aerospike SR-71 Experiment (LASRE)

This paper presents pertinent results and assessment of propellant feed system leak detection as applied to the Linear Aerospike SR-71 Experiment (LASRE) program flown at the NASA Dryden Flight Research Center, Edwards, California. The LASRE was a flight test of an aerospike rocket engine using liquid oxygen and high-pressure gaseous hydrogen as propellants. The flight safety of the crew and the experiment demanded proven technologies and techniques that could detect leaks and assess the integrity of hazardous propellant feed systems. Point source detection and systematic detection were used. Point source detection was adequate for catching gross leakage from components of the propellant feed systems, but insufficient for clearing LASRE to levels of acceptability. Systematic detection, which used high-resolution instrumentation to evaluate the health of the system within a closed volume, provided a better means for assessing leak hazards. Oxygen sensors detected a leak rate of approximately 0.04 cubic inches per second of liquid oxygen. Pressure sensor data revealed speculated cryogenic boiloff through the fittings of the oxygen system, but location of the source(s) was indeterminable. Ultimately, LASRE was cancelled because leak detection techniques were unable to verify that oxygen levels could be maintained below flammability limits.

Hass, Neal↗
NASA NTRS2012

Pressure Dome for High-Pressure Electrolyzer

A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom segment and is trapped by the flange on the top dome segment when these components are bolted together with high-strength bolts. The pressure dome has several unique features. It is made (to ASME Pressure Vessel guidelines) in a high-strength aluminum alloy with the strength of stainless steel and the weight benefits of aluminum. The flange of the upper dome portion contains specially machined flats for mounting the dome, and other flats dedicated to the special feedthroughs for electrical connections. A pressure dome can be increased in length to house larger stacks (more cells) of the same diameter with the simple addition of a cylindrical segment. To aid in dome assembly, two stainless steel rings are employed. One is used beneath the heads of the high-strength bolts in lieu of individual hardened washers, and another is used instead of individual nuts. Like electrolyzers could be operated at low or high pressures simply by operating the electrolyzer outside or inside a pressurized dome.

Norman, Timothy↗
NASA NTRS1994

Microfabricated Hydrogen Sensor Technology for Aerospace and Commercial Applications

Leaks on the Space Shuttle while on the Launch Pad have generated interest in hydrogen leak monitoring technology. An effective leak monitoring system requires reliable hydrogen sensors, hardware, and software to monitor the sensors. The system should process the sensor outputs and provide real-time leak monitoring information to the operator. This paper discusses the progress in developing such a complete leak monitoring system. Advanced microfabricated hydrogen sensors are being fabricated at Case Western Reserve University (CWRU) and tested at NASA Lewis Research Center (LeRC) and Gencorp Aerojet (Aerojet). Changes in the hydrogen concentrations are detected using a PdAg on silicon Schottky diode structure. Sensor temperature control is achieved with a temperature sensor and heater fabricated onto the sensor chip. Results of the characterization of these sensors are presented. These sensors can detect low concentrations of hydrogen in inert environments with high sensitivity and quick response time. Aerojet is developing the hardware and software for a multipoint leak monitoring system designed to provide leak source and magnitude information in real time. The monitoring system processes data from the hydrogen sensors and presents the operator with a visual indication of the leak location and magnitude. Work has commenced on integrating the NASA LeRC-CWRU hydrogen sensors with the Aerojet designed monitoring system. Although the leak monitoring system was designed for hydrogen propulsion systems, the possible applications of this monitoring system are wide ranged. Possible commercialization of the system will also be discussed.

Hunter, Gary W.↗
NASA NTRS2001

A Quadrupole Ion Trap Mass Spectrometer for Quantitative Analysis of Nitrogen-Purged Compartments within the Space Shuttle

To enter orbit the Space Shuttle burns 1.8 million liters of liquid hydrogen combined with 0.8 million liters of liquid oxygen through three rocket engines mounted in the aft. NASA monitors the nitrogen-purged aft compartment for increased levels of hydrogen or oxygen in order to detect and determine the severity of a cryogenic fuel leak. Current monitoring is accomplished with a group of mass spectrometer systems located as much as 400 feet away from the shuttle. It can take up to 45 seconds for gas to reach the mass spectrometer, which precludes monitoring for leaks in the final moments before liftoff (the orbiter engines are started at T-00:06 seconds). To remedy the situation, NASA is developing a small rugged mass spectrometer to be used as point-sources around the Space Shuttle.

Ottens, Andrew K.↗
NASA NTRS2008

Nanosensors for Evaluating Hazardous Environments

Personnel working in a confined environment can be exposed to hazardous gases, and certain gases can be extremely dangerous even in concentrations as low as a few parts per billion. Nanosensors can be placed in multiple locations over a large area, thus allowing for more precise and timely detection of gas leaks. ASRC Aerospace and its research partners are developing nanosensors to detect various gases, including hydrogen, ammonia, nitrogen tetroxide, and hydrazine. Initial laboratory testing demonstrated the capability to detect these gases in concentrations lower than parts per million, and current testing is evaluating sensitivity at concentration levels three orders of magnitude lower. Testing and development continue to improve the response and recovery times and to increase the sensitivity of the devices. The development team is evaluating different coatings and electrodes to determine the optimum configuration for detecting and identifying a variety of gases. The small footprint of the nanosensors allows several devices to be placed into a single substrate. Each sensor is responsive in a different way to different gases. Embedding multiple devices into a single substrate results in better reliability and less frequent calibrations. The use of different coatings for individual elements of a multichannel sensor allows different gases to be identified. The sensor system is implemented by the use of a custom multichannel signal conditioner amplifier built on a small multichip module. This device processes the output of the sensors and transmits a signal that can be monitored and analyzed remotely.

Source record↗
NASA NTRS2008

The Summer of Hydrogen

Ground crew veterans at Kennedy Space Center still talk about what they call "the summer of hydrogen"-the long, frustrating months in 1990 when the shuttle fleet was grounded by an elusive hydrogen leak that foiled our efforts to fill the orbiter's external fuel tank. Columbia (STS-35) was on Launch Pad A for a scheduled May 30 launch when we discovered the hydrogen leak during - tanking. The external fuel tank is loaded through the orbiter. Liquid hydrogen flows through a 17-inch umbilical between the orbiter and the tank. During fueling, we purge the aft fuselage with gaseous nitrogen to reduce the risk of fire, and we have a leak-detection system in the mobile launch platform, which samples (via tygon tubing) the atmosphere in and around the vehicle, drawing it down to a mass spectrometer that analyzes its composition. When we progressed to the stage of tanking where liquid hydrogen flows through the vehicle, the concentration of hydrogen approached four percent-the limit above which it would be dangerously flammable. We had a leak. We did everything we could think of to find it, and the contractor who supplied the flight hardware was there every day, working alongside us. We did tanking tests, which involved instrumenting the suspected leak sources, and cryo-loaded the external tank to try to isolate precisely where the leak originated. We switched out umbilicals; we replaced the seals between the umbilical and the orbiter. We inspected the seals microscopically and found no flaws. We replaced the recirculation pumps, and we found and replaced a damaged teflon seal in a main propulsion system detent cover, which holds the prevalve-the main valve supplying hydrogen to Space Shuttle Main Engine 3 -in the open position. The seal passed leak tests at ambient temperature but leaked when cryogenic temperatures were applied. We added new leak sensors-up to twenty at a time and tried to be methodical in our placements to narrow down the possible sources of the problem. We even switched orbiters, sending Columbia back to the Vehicle Assembly Building and bringing out Atlantis, scheduled to fly as STS-38. Two shuttles on their mobile launchers passing in the night was a majestic sight, but not one you want to see if you're trying to get an orbiter launched. None of this told us where the leak was, or if we were dealing with more than one leak source.

Weber, Philip↗
NASA NTRS2002

Development of Microfabricated Chemical Gas Sensors and Sensor Arrays for Aerospace Applications

Aerospace applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. In particular, factors such as minimal sensor size, weight, and power consumption are particularly important. Development areas which have potential aerospace applications include launch vehicle leak detection, engine health monitoring, fire detection, and environmental monitoring. Sensor development for these applications is based on progress in three types of technology: 1) Micromachining and microfabrication (Microsystem) technology to fabricate miniaturized sensors. 2) The use of nanocrystalline materials to develop sensors with improved stability combined with higher sensitivity. 3) The development of high temperature semiconductors, especially silicon carbide. However, due to issues of selectivity and cross-sensitivity, individual sensors are limited in the amount of information that they can provide in environments that contain multiple chemical species. Thus, sensor arrays are being developed to address detection needs in such multi-species environments. This paper discusses the needs of space applications as well as the point-contact sensor technology and sensor arrays being developed to address these needs. Sensors to measure hydrogen, hydrocarbons, hydrazine, nitrogen oxides (NO,), carbon monoxide, oxygen, and carbon dioxide are being developed as well as arrays for leak, fire, and emissions detection. Demonstrations of the technology will also be discussed. It is concluded that microfabricated sensor technology has significant potential for use in a range of aerospace applications.

Hunter, G. W.↗
NASA NTRS2005

Microfabricated Chemical Gas Sensors and Sensor Arrays for Aerospace Applications

Aerospace applications require the development of chemical sensors with capabilities beyond those of commercially available sensors. In particular, factors such as minimal sensor size, weight, and power consumption are particularly important. Development areas which have potential aerospace applications include launch vehicle leak detection, engine health monitoring, and fire detection. Sensor development for these applications is based on progress in three types of technology: 1) Micromachining and microfabrication (Microsystem) technology to fabricate miniaturized sensors; 2) The use of nanocrystalline materials to develop sensors with improved stability combined with higher sensitivity; 3) The development of high temperature semiconductors, especially silicon carbide. This presentation discusses the needs of space applications as well as the point-contact sensor technology and sensor arrays being developed to address these needs. Sensors to measure hydrogen, hydrocarbons, nitrogen oxides (NO,), carbon monoxide, oxygen, and carbon dioxide are being developed as well as arrays for leak, fire, and emissions detection. Demonstrations of the technology will also be discussed. It is concluded that microfabricated sensor technology has significant potential for use in a range of aerospace applications.

Hunter, Gary W.↗