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At least 343 records · Page 19

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Identifying Sources of Sulfate Preserved in High Elevation Lava Tubes From Mauna Loa, Hawaii

Volcanic sulfates record a history of their formation pathways in their triple oxygen isotope compositions, making them a powerful target for understanding atmospheric chemistry. To understand how these isotopic signals may be preserved in sulfate minerals, we investigate multiple O and S isotopes of thenardite, mirabilite, and gypsum from in a Mars analog environment: a pair of lava tubes near the summit of Mauna Loa, Hawaii. Based on 16 O-, 17 O- 18 O compositions, the primary oxygen sources for sulfates in the lava tube are atmospheric oxygen (O 2 ), peroxide (H 2 O 2 ), and ozone (O 3 ). We suggest the isotopic signature of O 2 originates from combustion of reduced sulfur gases and/or elemental sulfur at the eruptive source or within the lava tube soon after skylight collapse. Sulfate with isotopic signatures of peroxide and ozone are typically expected from aqueous reactions in cloud droplets. Chemical modeling indicates the observed proportion of ozone sourced sulfate requires pH greater than ~5.4, higher than measured cloud water pH, instead suggesting the observed O 3 signature could not have formed in cloud water droplets. We interpret that sulfate possessing an ozone signature in the lava tube sulfates formed on wetted surfaces of the lava tubes with alkalinity from alteration of basaltic glass. Furthermore, the oxygen and sulfur isotopes of the sulfate are uncorrelated. Multiple sulfur isotopes ( 32 S- 33 S- 34 S- 36 S) from the Mauna Loa sulfates are consistent with ocean island basalt from Pitcairn, suggesting the sulfate-sulfur has not been modified compared to its volcanic source. The findings of this study indicate that oxidation by ozone plays a key role in the formation of sulfate within lava tubes. We also find that combustion is a significant pathway toward sulfuric acid formation in volcanic environments. Similar signatures should be expected on other planets if volcanism is a significant sulfate source, as has been suggested for Mars. If true, sulfates in returned samples from Mars may hold key information on pO 2 , pCO 2 and planetary scale oxygen fluxes at the time of sulfate formation.

Justin Hayles↗

DOE OSTI2014

Multi-tube fuel nozzle with mixing features

A system includes a multi-tube fuel nozzle having an inlet plate and a plurality of tubes adjacent the inlet plate. The inlet plate includes a plurality of apertures, and each aperture includes an inlet feature. Each tube of the plurality of tubes is coupled to an aperture of the plurality of apertures. The multi-tube fuel nozzle includes a differential configuration of inlet features among the plurality of tubes.

42 ENGINEERING↗

DOE OSTI2016

Cap assembly for a bundled tube fuel injector

A cap assembly for a bundled tube fuel injector includes an impingement plate and an aft plate that is disposed downstream from the impingement plate. The aft plate includes a forward side that is axially separated from an aft side. A tube passage extends through the impingement plate and the aft plate. A tube sleeve extends through the impingement plate within the tube passage towards the aft plate. The tube sleeve includes a flange at a forward end and an aft end that is axially separated from the forward end. A retention plate is positioned upstream from the impingement plate. A spring is disposed between the retention plate and the flange. The spring provides a force so as to maintain contact between at least a portion of the aft end of the tube sleeve and the forward side of the aft plate.

42 ENGINEERING↗

DOE OSTI2016

Combustor having mixing tube bundle with baffle arrangement for directing fuel

A combustor includes a tube bundle that extends radially across at least a portion of the combustor. The tube bundle includes an upstream surface axially separated from a downstream surface, and a plurality of tubes extend from the upstream surface through the downstream surface to provide fluid communication through the tube bundle. A barrier extends radially inside the tube bundle between the upstream and downstream surfaces, and a baffle extends axially inside the tube bundle between the upstream surface and the barrier.

42 ENGINEERING↗

DOE OSTI2019

Resistance pressure weld for nuclear reactor fuel rod tube end plug

A fuel rod for a nuclear reactor, including a cladding tube having a first end with an annular end face, a second end with an annular end face, and a cylindrical body portion extending therebetween, and a first tube end plug including a front portion, an annular lip with an annular end face, and a substantially straight cylindrical body portion extending therebetween, wherein the surface area of the annular end face of the first end of the cladding tube and the annular end face of the annular lip of the first tube end plug are substantially equal, and the annular end face of the first end of the cladding tube and the annular end face of the annular lip of the first tube end plug are connected by a resistance pressure weld.

Barger, Earl Brian↗

DOE OSTI2021

Resistance pressure weld for nuclear reactor fuel rod tube end plug

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2021

Integrated tube-trailer and stationary ground storage system and method for enhanced pressure consolidation operations for refueling of gaseous fuels

An enhanced operating method and an integrated tube-trailers and stationary ground storage system are provided for implementing enhanced pressure consolidation operations for refueling gaseous fuels. The integrated tube-trailers and stationary ground storage system includes gaseous fuel supply tube-trailers and stationary ground storage including at least one or more stationary pressure vessels. A compressor can be supplied by both the stationary ground storage and the tube-trailers. The stationary ground storage can provide higher pressure to the compressor than the tube-trailers, enabling enhanced compressor throughput during refueling operation, and enhanced utilization of tube-trailers payload.

Elgowainy, Amgad↗

DOE OSTI2022

Measurement of Convective Heat Transfer Coefficients with Supercritical CO2 in Novel Additively Manufactured Helically Patterned Pin Fin Tubes Using the Wilson Plot Technique

This paper describes the measurement of convective heat transfer coefficients and friction factors for sCO2 flowing in pin-fin patterned pipes in the Heat Exchange and Experimental Testing (HEET) facility at the US DoE’s National Energy Technology Laboratory (NETL) in Morgantown, WV. The measurement procedures in the HEET rig were validated by conducting benchmark tests with smooth stainless-steel tube and comparing the results with published correlations for Nusselt number (Nu) and friction factor. Over typical Reynolds number range in sCO2, the measured Nu and friction factors were within 7% of classical correlations for smooth tube flow.The candidate pin fin patterned pipes were additively manufactured (AM) at the Oak Ridge National Laboratory. The pins were circular or elliptical in cross-section. Pin length to diameter aspect ratios were 1.33 and 2, while the pin diameter to tube diameter ratio was 0.188 and 0.125. Tests were performed for ReD varying from 6.9×104 to 2.2×105 and at conditions equivalent to the low pressure outlet (8.69 MPa, 361 K) of the low temperature recuperator (LTR) in an indirect sCO2 power cycle. The Wilson plot technique was utilized to measure the bulk heat transfer coefficients.For the better performing design (tube A, pin length to tube diameter ratio: 1.33, pin diameter to tube diameter ratio: 0.188), the local heat transfer coefficient increased by 112% relative to the Dittus-Boelter correlation at the LTR low pressure outlet. This corresponded to a 282% increase in the product of the heat transfer coefficient and the surface area. Large pressure drops across the test articles were observed.

Searle, Matthew↗

DOE OSTI2022

Flow Boiling Heat Transfer Characteristics of Water for Metal-foam-filled Horizontal Tubes

The goal of this paper is to enhance the in-tube flow boiling heat transfer of water while accounting for potential increase in pressure drop. Metal foams are a class of cellular structure with large surface-area-to-volume ratio and tortuous structure which has shown promising results for various energy conversion and storage applications. The higher heat transfer area and higher nucleation sites density due to the porous media can effectively enhance the heat transfer of water in both single-phase and two-phase operations. This paper presents the local heat transfer and pressure drop measurements of water in a partially metal-foam-filled horizontal copper tube. The ranges of parameters in the experiments are: mass flux from 80 to 200 kg/s-m2, heat flux from 3.5 to 105 kW/m2, and vapor quality from subcooled to 0.3. The results in the metal-foam-filled tube are compared with that of the bare copper tube. The effect of metal foam on the thermal hydraulic characteristics is discussed and analyzed. In addition, the two-phase flow behavior in a transparent tube filled with the same metal foam was visualized and investigated by high-speed imaging system. The experiments were also conducted in the tube without the metal foam for comparison.

Nawaz, Kashif↗

DOE OSTI2022

Enhanced Pool Boiling of Low-Pressure Refrigerants on Round Tubes- An Experimental Evaluation

Pool boiling heat transfer is one of the most effective heat transfer methos and crucial for several energy conversion processes such as electronic cooling, steam generation, water purification and thermal management. Enhancing boiling heat transfer around the tubes enables higher heat flux, which can improve the efficiency and lead to compact heat exchangers. Delaying the onset of critical heat flux (CHF) allows for higher CHFs and protects equipment during anomalous transient conditions. Growing interest in process intensification and delayed CHF has motivated the current study. An experimental approach has been deployed to investigate a potential technique to enhance the pool boiling performance around small diameter tubes by open cell metal foams. The findings for nucleate pool boiling of Novec HFE 7000 on the externally enhanced and smooth tubes are reported. The enhanced tube comprised of compressed aluminum foam brazed around. All the samples were horizontally oriented, and the experiments were performed under ambient pressure conditions. The heat transfer measurements for the smooth tubes were compared with several existing correlations and established the baseline. The preliminary results showed that the aluminum foam effectively enhanced the heat transfer coefficient and delayed the onset of critical heat flux. In addition, the pool boiling process around the round tube sample was visualized from both side and front views to comprehend the heat transfer mechanisms underlying substantial enhancement observed during experiments.

Yang, Cheng-Min↗

DOE OSTI2023

Method of making an annular radioisotope target having a helical coil-shaped foil ribbon between cladding tubes

An annular radioisotope target and method therefor that includes an inner cladding tube and a helical coil-shaped foil ribbon disposed over the inner cladding tube. The helical coil-shaped foil ribbon has a first end, a second end, a first edge and a second edge. An outer cladding tube is disposed over the helical coil-shaped foil ribbon and inner cladding tube, and end caps are attached to the outer cladding tube and the inner cladding tube.

Ripley, Edward B.↗

DOE OSTI2016

Design of a Supercritical Carbon Dioxide Corrosion Test Rig for Tube-to-Tubesheet Joint and High Temperature Insulation Testing

Supercritical carbon dioxide (S-CO{sub 2}) Brayton cycles are attractive for thermal power generation since they offer highly efficient means of power generation (thermal solar, coal, nuclear, etc.) with a compact footprint, resulting in potential cost savings. The University of California, Berkeley (UCB) is developing an S-CO{sub 2}- Brayton Cycle design for advanced reactors using sodium and molten salt coolants. Coiled tube gas heaters (CTGH) made from 316L stainless steel are presently foreseen to transfer heat from a sodium or molten salt coolant at atmospheric pressure (approximately 0.1 MPa) to an S-CO{sub 2} power conversion fluid at very high pressure (approximately 20 MPa or more). CTGHs operate at temperatures of 400 to 700 deg. C where time-dependent creep is an important design issue. Given the high external pressure conditions and compressive stress, the highest stresses and creep rates in CTGH are expected to occur at the tube-to-tubesheet joints. UCB has developed different diffusion bonding techniques to fabricate 316L stainless steel tube-to-tubesheet joint dummies representative of the final design: press fitting and diffusion bonding, tube expansion and diffusion bonding as well as hybrid friction diffusion bonding. High pressure/temperature testing of such joints in an S-CO{sub 2} environment is important prior to deployment and will be foreseen with the corrosion test rig introduced in this work. This summary provides a brief overview of an Innovative S-CO, creep corrosion test rig for tube-to-tube sheet joint testing currently under construction at UCB. In contrast to other comparable test rigs, the design (1) makes the samples an active part of the pressure barrier and (2) uses internal insulation to reduce the temperature at the vessel wall, allowing the vessel to be manufactured from commercial carbon steel. (authors)

42 ENGINEERING↗

DOE OSTI2022

A correlation-based approach for evaluating mechanical properties of nuclear fuel cladding tubes

The present work offers and evaluates a correlation-based approach to determine the tensile properties of nuclear fuel cladding tubes. A set of model materials with known properties (i.e., austenitic and ferritic steels, fcc- and hcp-alloys) were tested to build a correlation between conventional tensile tests and ring (hoop) and tube (axial) tests. It was shown that close-to-linear relationships exist for the basic mechanical properties (i.e., yield and ultimate stress, uniform and total elongation) between the uniaxial tensile test data and the ring and tube test data. Using the ring and tube specimen geometries, the feasibility of the approach was demonstrated via manufacturing and testing specimens from irradiated Zr and FeCrAl nuclear fuel cladding tubes. Limitations caused by specific deformation mechanisms (e.g., high ductility of 304L steel) were discussed in detail. The approach can be extended to other tubular products with different geometry and dimensions.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Flux Pinning-Induced Stress in a Long Hollow Cylindrical Superconductor Restricted by a Metal Tube

The tensile stress in a hollow cylindrical superconductor completely restricted by a metal tube in a parallel magnetic field is investigated. Using the plane strain approach, analytical expressions for the stress distribution of the superconductor and the contact stress between the metal tube and the superconductor are obtained and show that both the ratio of Young’s modulus and thickness ratio of the high-temperature superconductors and the metal tube significantly affect the stress distribution in the superconductor explicitly. In addition, the flux pinning-induced stress in the above-mentioned superconductor is systematically studied by the exponential critical state model during the field cooling process. The results indicate that the metal tube can reduce effectively the tensile stress in the hollow cylindrical superconductor during the magnetization process. The findings suggest that the appropriate selection of material parameters and size of the metal tube can improve superconductor performance efficiently.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Strength Variation in Processing Multiport Extrusion Tubes of A1100 and A3102 Alloys

The manufacturing process of multiport extrusion tubes generally includes homogenization, extrusion, roll leveling and heat treatment. In order to investigate the influence of the manufacturing procedures on strength variation of multiport extrusion tubes made of A1100 and A3102 alloys, the tube fabrication experiments and following materials characterization are carried out. The alloys’ stress–strain curves after every processing procedure are measured, and pressure-bearing capacity of the tubes is tested. The tubes’ strength and pressure-bearing capacity reach the peak values after straightening process and drop to the minimum after annealing. The contributions of solid solution hardening, grain boundary hardening and constituent particle strengthening to yield strength are evaluated. It is deduced that cluster hardening is the dominant strengthening mechanism for the as-homogenized and as-extruded samples; the contribution of clusters is second to work hardening after straightening process; slight cold work in conjunction with high-temperature annealing accelerates abnormal grain growth. The loss of strength increment from clusters can be interpreted by the remarkable reduction of high-angle grain boundaries after abnormal grain growth.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Effect of curvature on extensional stiffness matrix of 2-D braided composite tubes

In the micromechanical analysis of braided composite tubes, the effects of curvature are often ignored. This approach is acceptable for thin-walled tubes with a large radius. However, in case of small diameter thick-walled tubes, such an approach may lead to inaccurate results. Therefore, it is of interest to determine when the curvature effects of tubular geometry become important in micromechanics. In this study, the extensional stiffness matrix of 2-D braided composite tubes was calculated using a curved unit-cell. The periodicity was imposed in circumferential and longitudinal directions of the tube. The extensional stiffness coefficients were calculated by simulating an internal pressure test, uniaxial tensile test, and torsion test. The obtained stiffness coefficients were compared to those obtained using a flat unit-cell. The results of curved unit-cell were different from that of flat unit-cell. The differences in stiffness coefficients, calculated using curved and flat unit cells were as high as 13%.

42 ENGINEERING↗

DOE OSTI2025

Advances in understanding vacuum break dynamics in liquid helium-cooled tubes for accelerator beamline applications

Understanding air propagation and condensation following a catastrophic vacuum break in particle accelerator beamlines cooled by liquid helium is essential for ensuring operational safety. This review summarizes experimental and theoretical work conducted in our cryogenics lab to address this issue. Systematic measurements were performed to study nitrogen gas propagation in uniform copper tubes cooled by both normal liquid helium (He I) and superfluid helium (He II). These experiments revealed a nearly exponential deceleration of the gas front, with stronger deceleration observed in He II-cooled tubes. To interpret these results, a one-dimensional (1D) theoretical model was developed, incorporating gas dynamics, heat transfer, and condensation mechanisms. The model successfully reproduced key experimental observations in the uniform tube system. However, recent experiments involving a bulky copper cavity designed to mimic the geometry of a superconducting radiofrequency (SRF) cavity revealed strong anisotropic flow patterns of nitrogen gas within the cavity, highlighting limitations in extrapolating results from simplified tube geometries to real accelerator beamlines. To address these complexities, we outline plans for systematic studies using tubes with multiple bulky cavities and the development of a two-dimensional (2D) model to simulate gas dynamics in these more intricate configurations. As a result, these efforts aim to provide a comprehensive understanding of vacuum breaks in particle accelerators and improve predictive capabilities for their operational safety.

Beamline tube↗

DOE OSTI2022

Numerical simulation of falling film sensible heat transfer over round horizontal tubes

Numerical simulations are performed to explore the heat transfer characteristics of falling films over horizontal round tubes with uniform heat flux imposed for a range of Reynolds numbers spanning the droplet, jet, and sheet regimes. Simulations results agree well with available experimental measurements. The study analyzes the local as well as average heat transfer behavior under the different flow modes. The numerical results show that the local Nusselt number (Nu) distribution depends on the flow features in each mode and varies substantially in all directions for the respective mode. In the droplet mode, the Nu value varies significantly as the droplet impinges and the remnant liquid-bridge retracts (peak instantaneous Nu near 6), followed by wave propagation over the tube surface with peak Nu around 0.25. For the jet modes, the local maximum in the heat transfer occurs off-center to the impingement location with magnitudes of peak Nu = 3.1 for the inline jet mode and Nu = 2.7 for the staggered jet mode, while on the rest of the tube surface, it has an inverse relation with the liquid film thickness. Substantial variations in the heat transfer value are also recorded in the middle of the two impinging jets with Nu = 0.95 in the inline jet mode where the neighboring jets do not interact, and Nu = 0.60 in the crest region of the staggered jet mode where the neighboring jets interact with each other. In the sheet mode, the Nu was seen to depend on the thickness of the liquid waves traversing over the tube surface. Lower Nu values were recorded beneath the crest location of the liquid waves, which increases (1.4–11.6% depending on circumferential location) abruptly in magnitude at the advancing fronts of the waves. The temperature distribution in the liquid film in each of the modes was examined to evaluate the mechanism of heat transfer process. This study also compares the local heat transfer coefficient distribution with the analytical heat transfer models derived to predict heat transfer performance over horizontal tube surfaces.

42 ENGINEERING↗