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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 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Propellant Delivery via VDC Driven Pump

The SMART (Scalable Mobile Autonomous Rocket engine Test) testbed system initiative at SSC was conceived to attempt to address many of the principal cost drivers in developing and maintaining a rocket engine test facility. The system (optimized to test engines and components generating up to 10K lbf nominal thrust) is serving as a testbed for innovative technologies and processes to provide lower cost test services with a rapid test cadence and expedient turnaround times. The system can also potentially be used as a testbed to test other related technologies relevant to surface situations (e.g., moon, Mars associated with crogenic fluid management, engine/component testing, autonomous operations, etc.). This FY20 CIF project, being conducted as part of the SMART testbed system, is developing and testing a propellant delivery system via electrically driven centrifugal pumps (obviating dependence upon Multi-Layer Pressure Vessels) with configuration and operation by a minimal number of personnel. During FY20 the team identified the requirements and worked with P3 and Masten Space Systems to develop the long lead (9 months after receipt of order) items, the 400 VDC pumps, for delivery in mid FY21. Since control of the 400 VDC pump motor is not well developed the team has established heuristics to control flows in LN2 at off nominal shaft speeds to allow deep throttling of the pump in flow test scenarios. Various test scenarios including nominal i.e. high flow high pressure, high flow low pressure, low flow high pressure, low flow low pressure, minimum throttle step change, and low inlet pressure cavitation testing were developed ahead of the anticipated hardware delivery and test. FY20 COVID Stage 3 conditions restricted access to the center and hindered lab work, so efforts focused on the system design and testing plans along with the project procurement paperwork for the hardware... now with its anticipated delivery in spring FY21. Some limited access to the center is expected by spring/summer FY21 for the continuing second year (FY21) CIF project effort meant to be focused upon system integration and initial testing.

Aaron Head↗
NASA NTRSDate not supplied

Going beyond reliability to achieve robustness

Reliability is the ability to perform well and consistently. More formally, reliability is defined as the mathematical probability that a system does not fail during a specified time period under its specified operating conditions. The specified operating conditions often go beyond the nominal environment to include variations and challenges encountered in operational use. The difficulty is that systems are often operated outside of their specified operating conditions and, if they fail, the designers are in theory blameless. Unanticipated damaging events include internal failures, external disruptions in supporting systems, accidents, and repurposing. The most common explanation of a system failure is human error, which is usually the first assumption of the system designers. Robustness is the capability to perform without failure under a wide range of conditions that go beyond the specified operating conditions. The first step towards improving robustness would be to expand the system’s specified operating conditions to include a wider range of anticipated challenges, especially human error. Beyond this, there is a need for general approach to reduce the impact of unanticipated future events, the unknown unknowns, by improving the system’s general ability to cope. Robustness can be improved by providing additional processing capacity, larger flow control buffers, increased backup storage, more online redundancy, and more capable supervisory monitoring and control.

Harry W Jones↗
NASA NTRSDate not supplied

Viability of Small Dimension Crew Quarters for Surface Habitation

During early planning for the Artemis program’s sustained phase of lunar activity, NASA planners have been held to work towards a NASA reference lunar lander concept. With this activity taking place prior to the awarding of a lander contract, NASA planners cannot assume which of several potential landers will be available. This has limited habitation team engineers to a 12-metric ton mass limit for the reference concept of the lunar Surface Habitat. Consequently, minimal approaches have been applied to many habitat systems and it is important to determine acceptable volume for crew quarters. A number of both NASA and non-NASA surface habitat concepts have proposed relatively small crew quarters due to this constraint. Consequently, there is a need to collect objective test data to confirm or refute the validity of small crew quarters. NASA-STD-3001 is looked to for guidance in its many standards but offers little to no help. While prior versions called for private habitation, the current version – Revision B – calls for “individual privacy” to “accommodate social retreat.” Proposed Revision C modifications change the language slightly to “accommodate sleep and social retreat.” This is not enough guidance to determine the size of a crew quarters or even its capabilities. Unfortunately, only a small number of US spacecraft have included crew quarters, primarily the International Space Station and the Skylab Space Station. The space shuttle orbiter sometimes flew a set of private bunks that some might consider a crew quarters. All of these are dramatically smaller than US standards for minimum jail cells. The first opportunity for NASA to test a small crew quarters in a surface habitat application has been created through the Exploration Atmospheres test series, which is evaluating human performance under reduced cabin pressures. The test is converting the 20-Foot Vacuum Chamber at Johnson Space Center into a habitat, with the lower level outfitted as an EVA test area and the upper two levels for human habitation. The test will place eight people (six test subjects and two technicians) inside the chamber for eleven days. All eight will sleep in private quarters during the test. Volume limitations in the chamber forced extremely small crew quarters, measuring approximately 2 meters in length, 0.85 meters in height, and 0.9 meters in width. The test cabin pressure of 8.2 psi and elevated oxygen also introduces significant material limitations, limiting outfitting options. Nonetheless, the crew quarters design requirements were to accommodate visual separation, auditory separation, olfactory separation, tactile separation, air flow control, lighting control, single person personal computing, physical work surface access, sleep accommodations, non-sleep rest/relaxation, meditation, stretching, two-person meetings, snacking, changing clothes, viewing appearance, video communication, and audio communication. This paper will detail the acceptability of the crew quarters as measured in the October 2021 Exploration Atmosphere test. Based on this data, the viability of the type of crew quarters used in the 20 Foot Chamber will be assessed. Design recommendations for a 30-60-day Surface Habitat crew quarters will be provided, along with recommendations for future testing.

Crew Quarters↗
NASA NTRS2020

Maxar Electric Propulsion Development for Deep Space

Maxar has completed development activity for its deep-space electric propulsion system in support of NASA’s Psyche mission. Psyche’s electric propulsion system relies heavily on Maxar’s heritage EP-140 subsystem centered on the SPT-140. The evolution to the EP-140DS demonstrates an expanded thruster discharge capability from 0.9kW through 4.5kW and includes the addition of a constant keeper current function. This system, with development support from industry experts at JPL, will serve as the primary propulsion on board the Psyche spacecraft through the 3.6 year cruise to the Psyche asteroid. Subsystem level testing to validate the first EP-140DS design is complete. Major findings from system testing including xenon flow control loop timing, noise hardening, and constant keeper current and test activities are now being implemented in hardware and the status and plans are discussed.

Chaplin, Vernon↗
NASA NTRSDate not supplied

Development and Qualification Status of the Electric Propulsion Systems for the NASA PPE Mission and Gateway Program

NASA is charged with landing the first American woman and next American man on the South Pole of the Moon and establishing sustainable lunar exploration by the end of the decade. To meet this challenge, NASA’s Gateway will develop and deploy critical infrastructure required for operations on the lunar surface and that enables a sustained presence on and around the moon. NASA’s Power and Propulsion Element (PPE), the first planned element of NASA’s cis-lunar Gateway, leverages prior and ongoing NASA and U.S. industry investments in high-power, long-life solar electric propulsion technology investments. NASA awarded a PPE contract to Maxar Technologies to provide a 50 kW-class SEP spacecraft that meets Gateway’s needs, aligns with industry’s heritage spacecraft buses, and allows extensibility for NASA’s Mars exploration goals. Maxar’s PPE concept design, is based on their high heritage, modular, and highly reliable 1300-series bus architecture. The electric propulsion system features three 12 kW Advanced Electric Propulsion (AEPS) thrusters from Aerojet Rocketdyne and four BHT-6000 thrusters from Busek. Maxar-provided power electronics and xenon flow controllers from Moog are utilized in both the 12kW and 6kW electric propulsion strings on the spacecraft. The paper will present overviews of NASA’s Gateway and the PPE Project, status of the development and qualification activities for the two electric propulsion system, and the planned implementation of PPE electric propulsion system as keystone of NASA’s Gateway. The PPE spacecraft is currently heading into the Critical Design Review, with the qualification and flight electric propulsion hardware fabrication already initiated and significant progress being made toward planned qualifications in support of the planned PPE spacecraft co-manifest launch in 2024.

Electric Propulsion↗
NASA NTRSDate not supplied

PPE Electric Propulsion Advancing to CDR: 12kW String

String level testing is a vital part of electric propulsion development. With the Power and Propulsion Element (PPE) spacecraft flying two new models of Hall Thrusters, this work is even more critical. PPE will have both 6kW and 12kW thruster strings onboard, all powered by Maxar power processing units (PPU). Both strings have recently undergone end-to-end string level hot fire testing to verify the ability of all components to work together. This entails operating the thruster with the Xenon Flow Controller (XFC) and PPUs under both nominal and off-nominal conditions to stress the system and determine weak points. Such testing has long been a standard Maxar practice since our first 1.5kW electric propulsion system in 2004. This paper will focus on Phase 1 of the 12kW testing recently completed at NASA Glenn. The primary conclusion of the test effort was that the 12kW string operated nominally and that the PPU and XFC could operate the thruster within specifications.

Electric propulsion↗
NASA NTRSDate not supplied

Development and Qualification Status of the Electric Propulsion Systems for the NASA PPE Mission and Gateway Program

NASA is charged with landing the first American woman and next American man on the South Pole of the Moon and establishing sustainable lunar exploration by the end of the decade. To meet this challenge, NASA’s Gateway will develop and deploy critical infrastructure required for operations on the lunar surface and that enables a sustained presence on and around the moon. NASA’s Power and Propulsion Element (PPE), the first planned element of NASA’s cis-lunar Gateway, leverages prior and ongoing NASA and U.S. industry investments in high-power, long-life solar electric propulsion technology investments. NASA awarded a PPE contract to Maxar Technologies to provide a 50 kW-class SEP spacecraft that meets Gateway’s needs, aligns with industry’s heritage spacecraft buses, and allows extensibility for NASA’s Mars exploration goals. Maxar’s PPE concept design, is based on their high heritage, modular, and highly reliable 1300-series bus architecture. The electric propulsion system features three 12 kW Advanced Electric Propulsion (AEPS) thrusters from Aerojet Rocketdyne and four BHT-6000 thrusters from Busek. Maxar-provided power electronics and xenon flow controllers from Moog are utilized in both the 12kW and 6kW electric propulsion strings on the spacecraft. The paper will present overviews of NASA’s Gateway and the PPE Project, status of the development and qualification activities for the two electric propulsion system, and the planned implementation of PPE electric propulsion system as keystone of NASA’s Gateway. The PPE spacecraft is currently heading into the Critical Design Review, with the qualification and flight electric propulsion hardware fabrication already initiated and significant progress being made toward planned qualifications in support of the planned PPE spacecraft co-manifest launch in 2024.

Electric Propulsion↗
NASA NTRSDate not supplied

A Provably Correct Floating-Point Implementation of Well Clear Avionics Concepts

The NASA DAIDALUS library provides formal definitions for Detect-and-Avoid avionics concepts such as when an aircraft is well-clear with respect to the surrounding air traffic, i.e., it does not operate in such proximity to create a collision hazard. While several properties are proven correct for DAIDALUS assuming ideal real number arithmetic, an actual implementation that uses floating-point numbers may behave unexpectedly because of round-off errors and run-time exceptions. This paper presents an experience report on the application of a formal methods toolchain to extract and verify floating-point C code from a real-valued specification of the well-clear module of DAIDALUS. This toolchain comprises the PVS theorem prover, the PRECiSA floating-point analyzer and code generator, and the Frama-C analysis suite. The generated code is automatically instrumented to detect when the control flow of the floating-point program may diverge from the ideal real number specification, and it is annotated with contracts that state the maximum accumulated round-off error. The absence of overflows is also formally verified for the generated code. In order to apply the toolchain to an industrial case study such as DAIDALUS, a formally verified pre-processing of the input specification is performed, which includes a program slicing and several semantic-preserving simplifications.

Program verification↗
NASA NTRSDate not supplied

Flight Metal Plasma Thruster (MPT) Development, Qualification, and Thrust Measurement Campaign

A torsional thrust stand, calibrated for impulse bits in the range of 0.1mNs -0.5 mNs, was used to measure impulse bits during two campaigns at the NASA/GRC VF-3 Vacuum test Facility. Metal Plasma Thrusters (MPTs) with targets of Molybdenum, Copper and Stainless Steel (as used in upper stages of launch vehicles that are abandoned in LEO) were tested. This paper describes data from Mo targets (called pucks). The Cu and ss data will be presented elsewhere. Model predictions (based on a simple circuit model and published plasma parameters) were validated by data from the calibrated torsional thrust stand. The Metal Plasma Thruster uses solid metal propellant, hence requires no liquids, gases, flow valves or flow controls and has no moving parts. Total impulse ~5000Ns/U provides orbit raising and drag compensation capability.

Electric Propulsion↗
NASA NTRSDate not supplied

Flight MPT Development, Qualification and Thrust Measurement Campaign

A torsional thrust stand, calibrated for impulse bits in the range of 0.1mNs -0.5 mNs, was used to measure impulse bits during two campaigns at the NASA/GRC VF-3 Vacuum test Facility. Metal Plasma Thrusters (MPTs) with targets of Molybdenum, Copper and Stainless Steel (as used in upper stages of launch vehicles that are abandoned in LEO) were tested. This paper describes data from Mo targets (called pucks). The Cu and ss data will be presented elsewhere. Model predictions (based on a simple circuit model and published plasma parameters) were validated by data from the calibrated torsional thrust stand. The Metal Plasma Thruster uses solid metal propellant, hence requires no liquids, gases, flow valves or flow controls and has no moving parts. Total impulse ~5000Ns/U provides orbit raising and drag compensation capability.

Electric Propulsion↗
NASA NTRSDate not supplied

12-kW Advanced Electric Propulsion System Hall Current Thruster Qualification and Production Status

The AEPS contract was awarded to AR in May of 2016 with the goal of developing a 12.5kW Hall Thruster System, including the Hall Current Thruster (HCT), Power Processor Unit (PPU) and Xenon Flow Controller (XFC). It was originally targeted to support the Asteroid Redirect Mission, which was cancelled early in the project. The project was subsequently restructured to support the Gateway PPE propulsion mission, with modified scope that consisted of the development, qualification and delivery of three 12kW flight thrusters. The PPU and XFC components were designed and development hardware fabricated with initial testing performed prior to being de-scoped from the contract. System level testing was performed by AR using these engineering components in early 2022 at the Aerospace Corporation’s EP-3 test facility.

Hall thruster↗
DOE OSTI2017

Evaluation of Alternative Refrigerants for Mini-Split Air Conditioners

The phase-out of hydrochlorofluorocarbons (HCFC) refrigerants in developing countries is currently underway according to the Montreal Protocol. R-22 is one of the most commonly used HCFCs in the developing nations. It is extremely well suited for air conditioning and refrigeration (AC&R) in high ambient temperature environments. Non-Article 5 countries have already gone through the phase-out of HCFCs and settled on using R-410A as the refrigerant of choice for AC applications. Previous studies have shown that R-410A results in significant capacity and performance degradation at higher ambient temperature conditions. As such, there is a growing concern on finding alternative refrigerants to R-22 that would have zero ODP, lower GWP, and at the same time maintain acceptable performance at higher ambient temperatures. Furthermore, the developed world s transition through higher global warming potential (GWP) refrigerants like HFC and HFC blends resulted in significant direct CO2 equivalent emissions. It is imperative to develop a bridge for developing nations to avoid the transition from HCFC to HFC and then from HFC to alternative lower GWP refrigerants. This paper summarizes data from an experimental campaign on alternative refrigerant evaluation for R-22 and R-410A substitutes for mini-split air conditioners designed for high ambient environments. The experimental evaluation was performed according to ANSI/ASHRAE Standard 37 and the performance was rated at test conditions specified by ANSI/AHRI 210-240 and ISO 5151. Additional tests were conducted at outdoor ambient temperatures of 52 C (125.6 F) and 55 C (131 F) to evaluate their performance at high ambient conditions. Alternative refrigerants, some of which are proprietary, included R-444B, DR-3, N-20b, ARM-20b, R-290, and DR-93 as alternatives to R-22 and R-32, DR-55, L41-2, ARM-71A, and HPR-2A as alternatives to R-410A. The units performances were first verified using the baseline refrigerant and then drop-in refrigerant evaluation followed including soft optimization to ensure refrigerant performance is adequately represented. The soft optimization included: 1) charge optimization, 2) lubricant change, and 3) flow control. The paper presents the relative performances (efficiency and capacity) of the alternative refrigerants compared to the baseline refrigerants at the different operating conditions. Paper concludes with remarks about the suitability of alternative refrigerants for R-22 and R-410A applications in high ambient temperature regions.

Alternative Refrigerant↗
DOE OSTI2018

End-System Aware Peak Link Utilization Transport for Big Data Transfer over Dedicated Connections

High-performance networks provisioning 10/40-Gbps dedicated channels have been rapidly developed andincreasingly deployed to support big data transfers on the order of terabytes or petabytes in large-scale network-intensiveapplications. However, end users have not seen corresponding increase in application throughput mainly because traditional end-to-end transport methods are not optimized for such connections. New congestion or flow control mechanisms are desirable to meet the challenges brought to transport protocol design by dedicated connections. The advent and proliferation of multi-core processors make it now possible to improve application throughput by providing multiple processing and network resources to a single data transfer. Based on the existing PLUT method, we proposed a new dynamic buffer management scheme and an automatic parallelism tuning mechanism to achieve the maximal bottleneck rate. The performance superiority of PLUT is justified by the experimental results collected over a local 10Gbps dedicated connection.

Rao, Nageswara↗
DOE OSTI2018

Method to provide meta-stable operation of a DC microgrid comprising a pulsed load

A Hamiltonian surface shaping power flow control (HSSPFC) method is used to analyze the meta-stability and adjust pulsed power loads on a DC electric power distribution network. Pulsed power loads are nonlinear, time-variant systems that cause nonlinear limit-cycles. During the on periods of a pulsed load, the system can be in an unstable state and is damped back to stability during the off state of the load. Therefore, over the entire period of the pulse the system may only be assessed as meta-stable. As shown through simulation, HIL and hardware results, the HSSPFC method is more accurate than the other small-signal approaches, such as Eigenvalues, Nyquist, and Floquet theory, and can reveal important details about the transient responses and performance.

Wilson, David G.↗
DOE OSTI2019

Falling particle solar receivers

Falling particle solar receivers, systems, and methods are disclosed that include one non-linear falling particle curtain or two or more falling particle curtains within a solar receiver that receives incident solar radiation. The particles heated in the solar receiver may be used to heat a secondary fluid. In an embodiment, the particles may be recirculated to improve energy capture and thermal efficiency. In other embodiments, an air curtain may be used across the aperture of the receiver, and flow-control devices may be used to evenly spread particles across the width of the receiver inlet. Finally, feed particles may be preheated using heat from the solar receiver.

14 SOLAR ENERGY↗
DOE OSTI2019

Effect of Impurities in CO2 at Supercritical Pressure on Alloy Compatibility (EPRI)

Direct-fired supercritical CO2 (sCO2) cycles are expected to result in sCO2 with higher impurity levels compared to indirect-fired cycles. Prior work at ambient pressure showed minimal effects of O2 and H2O additions, however, a new experimental rig has been built to have flowing controlled impurity levels at supercritical pressures at ≤800°C. Based on industry input, the first experiment was conducted at 750°C/300 bar in CO2+1%O2-0.25%H2O using 500-h cycles for up to 5,000 h. Compared to research grade sCO2, the results indicate faster reaction rates for Fe-based alloys like 310HN and smaller increases for Ni-based alloys like alloys 617B and 282. It is difficult to quantify the 310HN rate increase because of scale spallation. Characterization of the 5,000 h specimens indicated a thicker reaction product formed, which has not been observed in previous impurity studies at ambient pressure. These results suggest that more studies of impurity effects are needed at supercritical pressures including steels at lower temperatures.

Pint, Bruce↗
DOE OSTI2020

Incineration system and process

An incineration system includes an inlet channel supplying an inlet stream comprising a waste gas containing at least one volatile organic compound, a waste gas sensor measuring at least one property of the waste gas, an oxidizing gas supply controllably providing oxidizing gas to the inlet channel, an incinerator receiving the inlet stream from the inlet channel, an ignitor initiating combustion of the inlet stream in the reaction zone of the incinerator, and a controller receiving data from the waste gas sensor and controlling flow of oxidizing gas from the oxidizing gas supply into the inlet channel. The spiral heat exchanger defines a reaction zone, an incoming path from the inlet channels to the reaction zone, and an outgoing path from the reaction zone to an exhaust channel. The incoming path and the outgoing path extend in alternating concentric spirals with the incoming path being countercurrent to the outgoing path.

42 ENGINEERING↗
DOE OSTI2021

Expanding thermite reactions for downhole applications

Methods and apparatus for forming platforms and flow control features in underground wells is described, using modified thermite reactions to form a ceramic plug in place. The reactive package is engineered to expand laterally, filling the well, and may be used to form a ceramic bridge plug, porous ceramic screen sections, or mitigate lost circulation of drilling fluids. These objectives are achieved through the design of the reactive package and through use of carefully chosen reaction additives that control the molten product rheology, solidification temperature, and pore generations and sustainment.

Lowry, William Edward↗