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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 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Manifold Integrated Pyrovalve

The Manifold Integrated Pyrovalve (MI-PV) provides a state-of-the-art, low mass, low volume, normally-closed (NC) pyrotechnic isolation valve configuration which is optimized for small free-flier applications. Small scale free-flier (e.g. CubeSat) applications require high pressure fluid isolation valves with leak rates low enough to endure long pad stays, and often have severe mass and volume limitations. The MI-PV utilizes a unique configuration where the shear section and the pyrotechnic ram assembly (PRA) are installed directly into a ported gas manifold, allowing elimination of heavy fluid fittings and connections. This configuration can be readily scaled and adapted to the needs of other long duration missions.

valve pyrovalve pyrotechnic↗
DOE OSTI2016

Hydraulic and mixing evaluations for SRS miscible liquid solutions

The hydraulic results demonstrate that pump head pressure of 20 psi recirculates about 5.6 liters/min flowrate through the existing 0.131-inch orifice when a valve connected to NT-41 is closed. In case of the valve open to NT-41, the solution flowrates to Savannah River Site (SRS) tanks, NT-21 and NT-41, are found to be about 0.5 lpm and 5.2 lpm, respectively. The modeling calculations for the mixing operations of miscible fluids contained in the SRS HB-Line tank NT-21 were performed by taking a three-dimensional Computational Fluid Dynamics (CFD) approach. The CFD modeling results were benchmarked against the literature results and the previous SRNL test results to validate the model. Final performance calculations were performed for the nominal case by using the validated model to quantify the mixing time for the HB-Line tank. The results demonstrate that when a pump recirculates a solution volume of 5.7 liters every minute out of the 72-liter tank contents containing two acid solutions of 2.7 M and 0 M concentrations (i.e., water), a minimum mixing time of 1.5 hours is adequate for the tank contents to get the tank contents adequately mixed. In addition, the sensitivity results for the tank contents of 8 M existing solution and 1.5 M incoming species show that the mixing time takes about 2 hours to get the solutions mixed. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Benefits of digitalizing and employing simulation to increase plant system performance and ensure compliance with technical specifications - 109

The essential services water system in a BWR nuclear power plant was affected by corrosion, soiling and blockages due to ageing. Those episodes affected safety margins hindering the Technical Specifications compliance during periodic system testing. Tecnatom designed, implemented and tested a design modification for the on-line monitoring of this system by integrating it in the existing Digital Control System (DCS). Key system parameters were acquired in real time to be displayed in the Human System Interface, used in performing calculations and stored their historical evolution. The objective was to optimize monitoring and surveillance of the essential service water system. Furthermore, Tecnatom developed an engineering simulator ('What if' simulator) consisting of a hydraulic model of the system. This simulator takes as inputs each heat exchanger performance parameters from the plant DCS, allows the user to change the essential services water system configuration (valves position, UHS level...) and calculates theoretical process values predicting the system real behavior. In a second stage, more system instruments were wired to the DCS for Technical Specifications compliance automatic surveillance regarding opening and closing times of system valves. Operating experience shows important benefits after the digitalization. It enhances on-line information of system operation and automates calculation of load loss factor of each heat exchanger. It eases the evaluation of blockages and soiling in the system allowing optimization of cleaning proceedings. System Surveillance Requirements and Test Requirements reports have been automated optimizing the operation workload. The simulator use enables to identify optimal system configuration increasing safety margins of the system and ensuring Technical Specifications fulfillment. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Failure Diagnosis for the Holdup Tank System via ISFA

This paper discusses the use of the integrated system failure analysis (ISFA) technique for fault diagnosis for the holdup tank system. ISFA is a simulation-based, qualitative and integrated approach used to study fault propagation in systems containing both hardware and software subsystems. The holdup tank system consists of a tank containing a fluid whose level is controlled by an inlet valve and an outlet valve. We introduce the component and functional models of the system, quantify the main parameters and simulate possible failure-propagation paths based on the fault propagation approach, ISFA. The results show that most component failures in the holdup tank system can be identified clearly and that ISFA is viable as a technique for fault diagnosis. Since ISFA is a qualitative technique that can be used in the very early stages of system design, this case study provides indications that it can be used early to study design aspects that relate to robustness and fault tolerance. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2017

Multifunctional Optoelectronic-Spintronic Device Based on Hybrid Organometal Trihalide Perovskites

A novel “hybrid” optoelectronic–spintronic (O-S) device that contains an organometal trihalide perovskite (OTP)-based solar cell or light-emitting diode coupled to an inorganic spin valve is presented. The synergy between the OTP and spin valve components results in two new functionalities: nonlinear magnetophotoconductivity and hysteretic magnetoelectroluminescence.

36 MATERIALS SCIENCE↗
DOE OSTI2020

First-Principles Quantum Transport Modeling of Spin-Transfer and Spin-Orbit Torques in Magnetic Multilayers

A unified approach for computing (i) spin-transfer torque in magnetic trilayers like spin valve and magnetic tunnel junction, where injected charge current flows perpendicularly to interfaces, and (ii) spin-orbit torque in magnetic bilayers of the type ferromagnet/spin-orbit-coupled material, where injected charge current flows parallel to the interface, was reviewed. The experimentally explored and technologically relevant spin-orbit-coupled materials include 5d heavy metals, topological insulators, Weyl semimetals, and transition metal dichalcogenides. This approach requires to construct the torque operator for a given Hamiltonian of the device and the steady-state nonequilibrium density matrix, where the latter is expressed in terms of the nonequilibrium Green’s functions and split into three contributions. Tracing these contributions with the torque operator automatically yields field-like and damping-like components of spin-transfer torque or spin-orbit torque vector, which is particularly advantageous for spin-orbit torque where the direction of these components depends on the unknown-in-advance orientation of the current-driven nonequilibrium spin density in the presence of spin-orbit coupling. Illustrative examples are provided by computing spin-transfer torque in a one-dimensional toy model of a magnetic tunnel junction and realistic Co/Cu/Co spin valve, both of which are described by first-principles Hamiltonians obtained from noncollinear density functional theory calculations, as well as by computing spin-orbit torque in a ferromagnetic layer described by a tight-binding Hamiltonian which includes spin-orbit proximity effect within ferromagnetic monolayers assumed to be generated by the adjacent monolayer transition metal dichalcogenide. In addition, it is shown here how spin-orbit proximity effect, quantified by computing (via first-principles retarded Green’s function) spectral functions and spin textures on monolayers of realistic ferromagnetic material like Co in contact with heavy metal or monolayer transition metal dichalcogenide, can be tailored to enhance the magnitude of spin-orbit torque. Furthermore, errors made in the calculation of spin-transfer torque are quantified when using Hamiltonian from collinear density functional theory, with rigidly rotated magnetic moments to create noncollinear magnetization configurations, instead of proper (but computationally more expensive) self-consistent Hamiltonian obtained from noncollinear density functional theory.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Beyond Annulus Size: Imaging for TAVR Planning

Purpose of Review: The aim of this article is to review the role of imaging in pre-procedural assessment prior to transcatheter aortic valve replacement (TAVR)—with a focus on relevant anatomic findings apart from the size of the aortic annulus. Recent Findings: Pre-procedure imaging prior to TAVR heavily emphasizes assessment of the aortic annulus for appropriate valve sizing, with computed tomography angiography (CTA) emerging as the test of choice due to its ability to assess not only the aortic annulus but also the thoracoabdominal aorta and peripheral vasculature. Some patients with underlying kidney disease may be at increased risk of renal dysfunction following contrast-enhanced CTA; however, alternate imaging techniques can be performed to mitigate this risk such as magnetic resonance imaging. Summary: Familiarity with underlying anatomic variability and pathology relevant to TAVR implantation in addition to annulus size, as well as imaging approaches in patients with renal dysfunction, will allow radiologists to better contribute to multidisciplinary discussion for potential TAVR candidates.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Benchmark study of the DTU OWC chamber with both two-way and one-way absorption

This paper reports on a benchmark study based on small-scale (1:50) measurements of a single, oscillating water column chamber mounted sideways in a long flume. The geometry of the OWC chamber is extracted from a barge-like, attenuator-type floating concept “KNSwing” with 40 chambers targeted for deployment in the Danish part of the North Sea. In addition to traditional two-way energy extraction we also consider one-way energy extraction with passive venting and compare chamber response, pressures and total absorbed energy between the two methods. A blind study was established for the numerical modeling, with participants applying several implementations of weakly nonlinear potential flow theory and commercial Navier–Stokes solvers (CFD). Both compressible and incompressible models were used for the air phase. Potential flow calculations predict more energy absorption near the chamber resonance for one-way absorption than for two-way absorption, but the opposite is found from the experimental measurements. This outcome is mainly attributed to energy losses in the experimental passive valve system, but this conclusion must be confirmed by better experimental measurements. Modeling the one-way valve in CFD proved to be very challenging and only one team was able to provide results which were generally closer to the experiments. The study illustrates the challenges associated with both numerical and experimental analysis of OWC chambers. Air compressibility effects were not found to be important at this scale, even with the large volume of additional air used for the one-way case.

16 TIDAL AND WAVE POWER↗
DOE OSTI2017

Novel volumetric method for highly repeatable injection in microchip electrophoresis

A novel injector for microchip electrophoresis (MCE) has been designed and evaluated that achieves very high repeatability of injection volume suitable for quantitative analysis. It eliminates the injection biases in electrokinetic injection and the dependence on pressure and sample properties in hydrodynamic injection. The microfluidic injector, made of poly(dimethylsiloxane) (PDMS), operates similarly to an HPLC injection valve. It contains a channel segment (chamber) with a well-defined volume that serves as an “injection loop”. Using on-chip microvalves, the chamber can be connected to the sample source during the “loading” step, and to the CE separation channel during the “injection” step. Once the valves are opened in the second state, electrophoretic potential is applied to separate the sample. For evaluation and demonstration purposes, the microinjector was connected to a 75 μm ID capillary and UV absorbance detector. For single compounds, a relative standard deviation (RSD) of peak area as low as 1.04% (n = 11) was obtained, and for compound mixtures, RSD as low as 0.40% (n = 4) was observed. Using the same microchip, the performance of this new injection technique was compared to hydrodynamic injection and found to have improved repeatability and less dependence on sample viscosity. Furthermore, a non-radioactive version of the positron-emission tomography (PET) imaging probe, FLT, was successfully separated from its known 3 structurally-similar byproducts with baseline resolution, demonstrating the potential for rapid, quantitative analysis of impurities to ensure the safety of batches of short-lived radiotracers. Both the separation efficiency and injection repeatability were found to be substantially higher when using the novel volumetric injection approach compared to electrokinetic injection (performed in the same chip). This novel microinjector provides a straightforward way to improve the performance of hydrodynamic injection and enables extremely repeatable sample volume injection in MCE. It could be used in any MCE application where volume repeatability is needed, including the quantitation of impurities in pharmaceutical or radiopharmaceutical samples.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

The design of an additive manufactured dual arm manipulator system

Additive manufacturing (AM), commonly referred to as 3D printing, was originally used for rapid prototyping. However, research into new technologies has allowed AM to become applicable far beyond prototype fabrication. Oak Ridge National Laboratory (ORNL), sponsored by the Office of Naval Research, has designed and developed an anthropomorphic seven degree-of-freedom (DOF) dual arm hydraulic manipulator using metal AM technologies. The titanium manipulators were designed for subsea use. All electrical and fluidic passageways are printed into each arm. The novel, cam-based design uses low-flow, energy efficient valves. The hydraulic power unit is built into the base of the hydraulic arms’ mount. This article will detail the novel AM design of the hydraulic manipulator system. It will cover the manipulators’ pitch and rotary link designs, custom valves, hydraulic power unit, and the motivation for a dual arm design. This article will also describe lessons learned throughout the project and draw conclusions for future applications.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Multi-level computational exploration of advanced combustion engine operating strategies

Advanced combustion engine (ACE) research is typically carried out on single-cylinder research engines. These engines are designed to tightly control fueling and conditions at intake valve closure (IVC) and to precisely measure in-cylinder conditions and emissions. However, to be able to measure and control engine operation so precisely, these research engines typically do not feature intake and exhaust tracts that resemble those in production engines, specifically in regards to turbomachinery, heat exchangers, and exhaust gas recirculation (EGR) systems. For this reason, these research engines are effective for understanding in-cylinder combustion parameters such as heat release rate, burn duration, combustion efficiency, pollutant formation, and exhaust valve opening (EVO) conditions. Here, this paper applies high fidelity simulations to determine the feasibility of achieving a chosen single cylinder engine operating point on a production type homogeneous charge compression ignition (HCCI) engine, using a partial fuel stratification (PFS) strategy. To accomplish this, a Converge 3 dimensional (3D) – computational fluid dynamics (CFD) model of the experimental combustion chamber and intake and exhaust runners was created to simulate the experimental engine. This model was used to simulate an operating point achieved experimentally, as well as to determine the sensitivity of the operating point to variations in intake pressure, intake temperature, injection timing, injected mass, and EGR fraction. The results from these simulations were fed into a 1-dimensional engine simulation created in AVL Boost, featuring production-type intake and exhaust systems, including turbomachinery and heat exchangers necessary to create the required IVC conditions. This full engine simulation was used to assess the cycle efficiency of the engine at the experimental operating condition, and to assess whether changes to this operating point in intake temperature, intake pressure, direct injection timing, or fueling are beneficial to the cycle efficiency and engine-out emissions. In addition, the sensitivity of promising engine operating points to injection timing and injection mass are determined to evaluate the potential stability of these operating points.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2017

Cost comparison of printed circuit heat exchanger to low cost periodic flow regenerator for use as recuperator in a s-CO 2 Brayton cycle

Supercritical Carbon Dioxide (sCO 2 ) power cycles have the potential to deliver high efficiency at low cost. However, in order for an sCO 2 cycle to reach high efficiency, highly effective recuperators are needed. These recuperative heat exchangers must transfer heat at a rate that is substantially larger than the heat transfer to the cycle itself and can therefore represent a significant portion of the power block costs. Regenerators are proposed as a cost saving alternative to high cost printed circuit recuperators for this application. A regenerator is an indirect heat exchanger which periodically stores and releases heat to the working fluid. The simple design of a regenerator can be made more inexpensively compared to current options. The objective of this paper is a detailed evaluation of regenerators as a competing technology for recuperators within an sCO 2 Brayton cycle. The level of the analysis presented here is sufficient to identify issues with the regenerator system in order to direct future work and also to clarify the potential advantage of pursuing this technology. A reduced order model of a regenerator is implemented into a cycle model of an sCO 2 Brayton cycle. An economic analysis investigates the cost savings that is possible by switching from recuperative heat exchangers to switched-bed regenerators. The cost of the regenerators was estimated using the amount of material required if the pressure vessel is sized using ASME Boiler Pressure Vessel Code (BPVC) requirements. The cost of the associated valves is found to be substantial for the regenerator system and is estimated in collaboration with an industrial valve supplier. The result of this analysis suggests that a 21.2% reduction in the contribution to the Levelized Cost of Electricity (LCoE) from the power block can be realized by switching to a regenerator-based system.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Multiple injection for improving knock, gaseous and particulate matter emissions in direct injection SI engines

Advances in fuel injector technology have enabled research and development on a large variety of direct injection spark ignition (DISI) engine fueling strategies targeted to improve engine performance and reduce engine-out emissions. This study explores the effect of multiple injections on knock, engine efficiency and stability, and particulate number and gaseous emissions on a single-cylinder DISI research engine. Work to date on multiple injections in the literature is reviewed, and then two aspects of multiple injection strategies are experimentally investigated: the number of injections (up to five times in a cycle); and the timing of the injections (classified relative to the timing of intake valve opening and closing). A boosted, single-cylinder research engine equipped with a state-of-the-art piezoelectric hollow cone spray direct injector and research-grade E10 gasoline was used for the study. The results show multiple injections maintain torque and combustion stability compared with single injection and slightly increase the knock limits and indicated thermal efficiencies (maximum 0.7% absolute, 2.8% relative compared with single-injection baseline) due to improved heat release phasing, especially with an additional late injection during the intake valve closed (compression stroke) period. The gaseous pollutant emissions including nitrogen oxides and unburned hydrocarbons were reduced by 25% with multiple injections, particularly with injection during the compression stroke. In contrast, carbon monoxide emissions increased with multiple injections for all conditions. Increasing the number of injection events significantly reduced particulate number emissions (half with each additional injection), and the decrease in particulate number was not sensitive to the injection timing.

42 ENGINEERING↗
DOE OSTI2019

Preliminary experimental comparison and feasibility analysis of CO2/R134a mixture in Organic Rankine Cycle for waste heat recovery from diesel engines

This paper presents results of a preliminary experimental study of the Organic Rankine Cycle (ORC) using CO2/R134a mixture based on an expansion valve. The goal of the research was to examine the feasibility and effectiveness of using CO 2 mixtures to improve system performance and expand the range of condensation temperature for ORC system. The mixture of CO 2 /R134a (0.6/0.4) on a mass basis was selected for comparison with pure CO 2 in both the preheating ORC (P-ORC) and the preheating regenerative ORC (PR-ORC). Then, the feasibility and application potential of CO 2 /R134a (0.6/0.4) mixture for waste heat recovery from engines was tested under ambient cooling conditions. Preliminary experimental results using an expansion valve indicate that CO 2 /R134a (0.6/0.4) mixture exhibits better system performance than pure CO 2 . For PR-ORC using CO 2 /R134a (0.6/0.4) mixture, assuming a turbine isentropic efficiency of 0.7, the net power output estimation, thermal efficiency and exergy efficiency reached up to 5.30 kW, 10.14% and 24.34%, respectively. For the fitting value at an expansion inlet pressure of 10 MPa, the net power output estimation, thermal efficiency and exergy efficiency using CO2/R134a (0.6/0.4) mixture achieved increases of 23.3%, 16.4% and 23.7%, respectively, versus results using pure CO2 as the working fluid. Finally, experiments showed that the ORC system using CO2/R134a (0.6/0.4) mixture is capable of operating stably under ambient cooling conditions (25.2-31.5 °C), demonstrating that CO 2 /R134a mixture can expand the range of condensation temperature and alleviate the low-temperature condensation issue encountered with CO 2 . Under the ambient cooling source, it is expected that ORC using CO 2 /R134a (0.6/0.4) mixture will improve the thermal efficiency of a diesel engine by 1.9%.

42 ENGINEERING↗
DOE OSTI2016

Development and evaluation of virtual refrigerant mass flow sensors for fault detection and diagnostics

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study evaluates three VRMFs for estimating refrigerant mass flow rate. The first model uses a compressor map that relates refrigerant flow rate to measurements of inlet and outlet pressure, and inlet temperature measurements. The second model uses an energy-balance method on the compressor that uses a compressor map for power consumption, which is relatively independent of compressor faults that influence mass flow rate. The third model is developed using an empirical correlation for an electronic expansion valve (EEV) based on an orifice equation. The three VRMFs are shown to work well in estimating refrigerant mass flow rate for various systems under fault-free conditions with less than 5% RMS error. Each of the three mass flow rate estimates can be utilized to diagnose and track the following faults: 1) loss of compressor performance, 2) fouled condenser or evaporator filter, 3) faulty expansion device, respectively. For example, a compressor refrigerant flow map model only provides an accurate estimation when the compressor operates normally. When a compressor is not delivering the expected flow due to a leaky suction or discharge valve or other internal fault, the energy-balance or EEV model can provide accurate flow estimates. In this paper, the flow differences provide an indication of loss of compressor performance and can be used for fault detection and diagnostics.

Kim, Woohyun↗
DOE OSTI2024

Effect of Inlet Throttling on Thermohydraulic Instability in a Large Scale Waterbased RCCS: A System-Level Analysis with RELAP5-3D

This paper presents results from system -level modeling of a water -based reactor cavity cooling system using RELAP5-3D. The computational model is benchmarked with experimental data from a half -scale RCCS test facility at Argonne National Laboratory. The model prediction is first compared with a two-phase oscillatory baseline experimental case where mixed accuracy is obtained. The model shows reasonable prediction of mass flow rate, pressure, and temperature but significant overprediction of void fraction. The model prediction is then compared with a fault case where the inlet of the risers is gradually reduced using a throttling valve. As the valve is closed, the model is able to predict some major flow phenomena observed in the experiment such as the dampening of oscillations, the reintroduction of oscillations, as well as boiling, flashing, and geysering in the risers. However, the timeline of these events are not well captured by the model. The model is also used to investigate the evolution of flow regime in the chimney. This work highlights that the semiempirical constitutive relations used in RELAP-3D could have a strong influence on the accuracy of the model in two-phase oscillatory flows.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

Optically pumped polarized 3 He ++ ion source development for RHIC/EIC

The proposed polarized 3 He ++ acceleration in RHIC and the future Electron-Ion Collider will require about 2×10 11 ions in the source pulse. A new technique had been proposed for production of high intensity polarized 3 He ++ ion beams. It is based on ionization and accumulation of the 3 He gas (polarized by metastability-exchange optical pumping and in the 5T high magnetic field) in the existing Electron Beam Ion Source (EBIS). A novel 3 He cryogenic purification and storage technique was developed to provide the required gas purity. An original gas refill and polarized 3 He gas injection to the EBIS long drift tubes, (which serves as the storage cell) were developed to ensure polarization preservation. An infrared laser system for optical pumping and polarization measurements in the high 3–5 T field has been developed. The 3 He polarization 80–85% (and sufficiently long ~30 min relaxation time) was obtained in the “open” cell configuration with refilling valve tube inlet and isolation valve closed. The development of the spin-rotator and 3 He 4 He absolute nuclear polarimeter at 6 MeV 3 He ++ beam energy is also presented here in this work.

43 PARTICLE ACCELERATORS↗