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

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Tube-in-tube ionic liquid heat exchanger employing a selectively permeable tube

A tube-in-tube heat exchanger utilizes a selectively permeable tube having a selective permeable layer to allow the refrigerant to transfer into an ionic liquid to generate heating or cooling. The ionic liquid then provides heating or cooling to a heat transfer fluid through a non-permeable layer or tube. The system may be configured as a shell and tube design, with the third fluid free to flow on the outside of the shell, or as a shell and tube-in-tube, with a central tube containing a first liquid, a second tube containing a second liquid, and an outer shell containing the third liquid. The selectively permeable tube may include an anion or cation selectively permeable layer and this layer may be supported by a support layer or tube.

Bahar, Bamdad↗
DOE OSTI2024

Tube-in-tube ionic liquid heat exchanger employing a selectively permeable tube

A tube-in-tube heat exchanger utilizes a selectively permeable tube having a selective permeable layer to allow the refrigerant to transfer into an ionic liquid to generate heating or cooling. The ionic liquid then provides heating or cooling to a heat transfer fluid through a non-permeable layer or tube. The system may be configured as a shell and tube design, with the third fluid free to flow on the outside of the shell, or as a shell and tube-in-tube, with a central tube containing a first liquid, a second tube containing a second liquid, and an outer shell containing the third liquid. The selectively permeable tube may include an anion or cation selectively permeable layer and this layer may be supported by a support layer or tube.

Bahar, Bamdad↗
DOE OSTI2017

THE TOPOLOGY OF CANONICAL FLUX TUBES IN FLARED JET GEOMETRY

Magnetized plasma jets are generally modeled as magnetic flux tubes filled with flowing plasma governed by magnetohydrodynamics (MHD). We outline here a more fundamental approach based on flux tubes of canonical vorticity, where canonical vorticity is defined as the circulation of the species’ canonical momentum. This approach extends the concept of magnetic flux tube evolution to include the effects of finite particle momentum and enables visualization of the topology of plasma jets in regimes beyond MHD. A flared, current-carrying magnetic flux tube in an ion-electron plasma with finite ion momentum is thus equivalent to either a pair of electron and ion flow flux tubes, a pair of electron and ion canonical momentum flux tubes, or a pair of electron and ion canonical vorticity flux tubes. We examine the morphology of all these flux tubes for increasing electrical currents, different radial current profiles, different electron Mach numbers, and a fixed, flared, axisymmetric magnetic geometry. Calculations of gauge-invariant relative canonical helicities track the evolution of magnetic, cross, and kinetic helicities in the system, and show that ion flow fields can unwind to compensate for an increasing magnetic twist. The results demonstrate that including a species’ finite momentum can result in a very long collimated canonical vorticity flux tube even if the magnetic flux tube is flared. With finite momentum, particle density gradients must be normal to canonical vorticities, not to magnetic fields, so observations of collimated astrophysical jets could be images of canonical vorticity flux tubes instead of magnetic flux tubes.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Development of an Innovative Inspection Tool for Superheater Tubes in Fossil Fuel Power Plants

Fossil fuel power plants are complex systems containing multiple components that require periodic health monitoring. Failures in these systems can lead to increased downtime for the plant, reduction of power, and significant cost for repairs. Inspections of the plant’s superheater tubes are typically manual, laborious, and extremely time-consuming. This is due to their small diameter size (between 1.3 and 7.6 cm) and the coiled structure of the tubing. In addition, the tubes are often stacked close to each other, limiting access for external inspection. This paper presents the development and testing of an electrically powered pipe crawler that can navigate inside 5 cm diameter tubes and provide an assessment of their health. The crawler utilizes peristaltic motion within the tubes via interconnected modules for gripping and extending. The modular nature of the system allows it to traverse through straight sections and multiple 90° and 180° bends. Additional modules in the system include an ultrasonic sensor for tube thickness measurements, as well as environmental sensors, a light detecting and ranging (LiDAR) sensor, and camera. Furthermore, these modules utilize a gear system that allows for 360° rotation and provides a means to inspect the entire internal circumference of the tubes.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Heat Transfer Coefficients of Additively Manufactured Tubes with Internal Pin Fins for Supercritical Carbon Dioxide Cycle Recuperators

This paper describes the measurement of convective heat transfer coefficients and friction factors for sCO 2 flowing in additively manufactured tubes with internal pin fins at the US DOE’s National Energy Technology Laboratory in Morgantown, WV. The measurement procedures 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 Reynolds numbers (ReD) ranging from 5 × 10 4 to 2.5 × 10 5 , measured Nu was within 5% of the Dittus-Boelter correlation and measured friction factors were within 5% of the McAdams correlation 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 and were printed at a 30⁰ angle relative to the inner wall (to meet AM constraints). The pin arrangement was helical to promote enhanced heat transfer due to swirl flow. Pin length to diameter aspect ratio was 1.33, 2, and 8, while the pin diameter to tube diameter ratio was 0.188, 0.125, and 0.063. Tests were performed for ReD varying from 6.9 × 10 4 to 2.2 × 10 5 and at conditions equivalent to the low pressure (LP) outlet (8.69 MPa, 361 K) and the high pressure (HP) inlet (20.7 MPa, 350 K) of the low temperature recuperator (LTR) in an indirect sCO 2 cycle. The Wilson plot technique was utilized to measure the bulk heat transfer coefficients. For the best performing design (tube A, pin length to tube diameter ratio: 1.33, pin diameter to tube diameter ratio: 0.19), the local heat transfer coefficient increased by 136% relative to the Dittus-Boelter correlation at the LTR low pressure outlet and 194% at the LTR high pressure inlet. These correspond to a 282% and a 271% increase in the product of the heat transfer coefficient and surface area (adjusted for fin efficiency) product, respectively. Large pressure drops across the test articles were observed. For Tube Design A, the average friction factor, across the range of ReD considered, was significantly larger than the McAdams correlation at both the LTR LP outlet and the LTR HP inlet. A thermal performance factor was utilized to express the ratio of material required to build a finned heat exchanger relative to a finless heat exchanger with the same heat duty and pumping power. Tube Design A was estimated to decrease the required heat exchanger material by 13%.

Searle, Matthew↗
DOE OSTI2020

Experimental and Numerical Investigation of a Miniature Additively Manufactured Vortex Tube

Ranque–Hilsch vortex tubes are simple devices that can produce a cooling effect using compressed air. A key advantage of vortex tubes is the lack of moving solid parts; however, their efficiencies are relatively low. The present study focuses on the development of a miniature variable-diameter tube using additive manufacturing. A metal-based 3D printing technique was utilized to fabricate this vortex tube monolithically. Computational fluid dynamics simulations employing software STAR-CCM + with a compressible Reynolds-Averaged Navier–Stokes (RANS) approach and the elliptic-blending lag k-epsilon turbulence model have been applied to model thermofluid processes inside the vortex tube, to good agreement with the experiment. In conclusion, a temperature decrease of 13.3 °C and a cooling power of approximately 4 W were experimentally achieved with a pressure ratio of 4 in the air at normal conditions. This result shows promise for the goal of utilizing additive manufacturing to design and build complex-geometry vortex tubes intended for use with cryogenic fluids.

08 HYDROGEN↗
DOE OSTI2014

Characterization of ultrafine-grained aluminum tubes processed by Tube Cyclic Extrusion–Compression (TCEC)

Tube Cyclic Extrusion–Compression as a novel severe plastic deformation technique for tubes was utilized for processing ultrafine grained 1050 aluminum alloy for the first time. In this method, aluminum tube is fully constrained and deformed between mandrel and chamber with a small neck zone. The material deformation during Tube Cyclic Extrusion–Compression processing analyzed and the grain refinement mechanism were described. The capability of Tube Cyclic Extrusion–Compression in grain refinement of the aluminum alloy was demonstrated by transmission electron microscopy observations and X-ray diffraction line profile analysis. The micrographs of the evolved microstructure show grain size of 850 nm and 550 nm after the first and second processing cycles of Tube Cyclic Extrusion–Compression, respectively. Mechanical properties of the initial and processed specimens were extracted from ring-hoop tensile tests. The documented results confirm grain refinement by showing remarkable increase in the yield and ultimate strengths. The main increase in strength and decrease in elongation take place after the first cycle. The microhardness assessments illustrate increase from the initial value of 29 Hv to 44 and 49 Hv respectively after the first and second cycles of Tube Cyclic Extrusion–Compression. There is a good homogeneity in peripheral microhardness and microhardness across the tube thickness. - Highlights: • Tubes of AA1050 for the first time were successfully SPD processed by TCEC. • The grain size was refined to 550 nm after two cycles of TCEC. • Notable increase in the strength and decrease in the elongation were documented. • The microhardness increased to 49 Hv from the initial value of 29 Hv. • Good homogeneity in the microhardness distribution was recorded.

36 MATERIALS SCIENCE↗
DOE OSTI2014

SU-E-I-25: Determining Tube Current, Tube Voltage and Pitch Suitable for Low- Dose Lung Screening CT

Purpose: The quality of a computed tomography (CT) image and the dose delivered during its acquisition depend upon the acquisition parameters used. Tube current, tube voltage, and pitch are acquisition parameters that potentially affect image quality and dose. This study investigated physicians' abilities to characterize small, solid nodules in low-dose CT images for combinations of current, voltage and pitch, for three CT scanner models. Methods: Lung CT images was acquired of a Data Spectrum anthropomorphic torso phantom with various combinations of pitch, tube current, and tube voltage; this phantom was used because acrylic beads of various sizes could be placed within the lung compartments to simulate nodules. The phantom was imaged on two 16-slice scanners and a 64-slice scanner. The acquisition parameters spanned a range of estimated CTDI levels; the CTDI estimates from the acquisition software were verified by measurement. Several experienced radiologists viewed the phantom lung CT images and noted nodule location, size and shape, as well as the acceptability of overall image quality. Results: Image quality for assessment of nodules was deemed unsatisfactory for all scanners at 80 kV (any tube current) and at 35 mA (any tube voltage). Tube current of 50 mA or more at 120 kV resulted in similar assessments from all three scanners. Physician-measured sphere diameters were closer to actual diameters for larger spheres, higher tube current, and higher kV. Pitch influenced size measurements less for larger spheres than for smaller spheres. CTDI was typically overestimated by the scanner software compared to measurement. Conclusion: Based on this survey of acquisition parameters, a low-dose CT protocol of 120 kV, 50 mA, and pitch of 1.4 is recommended to balance patient dose and acceptable image quality. For three models of scanners, this protocol resulted in estimated CTDIs from 2.9–3.6 mGy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Branched tube network and temperature regulating garment with branched tube network

In an embodiment of the present disclosure, a garment for regulating a temperature of a wearer is provided. The garment includes a fabric configured to be worn by the wearer. The fabric includes channels parallel to a primary surface of the fabric. The garment includes a branched tube network for circulating a working fluid. The branched tube network is disposed in the channels of the fabric. The branched tube network includes a plurality of tubes wherein at least one end of each tube of the plurality of tubes is branched and connected to two daughter tubes, or more, the connection having a branch angle of between 1 and 359 degrees, inclusive. The tube network has at least two levels of branches.

Fan, Jintu↗
DOE OSTI2021

Ultra-low-density digitally architected carbon with a strutted tube-in-tube structure

Porous materials with engineered stretching-dominated lattice designs, which offer attractive mechanical properties with ultra-light weight and large surface area for wide-ranging applications, have recently achieved near-ideal linear scaling between stiffness and density. Here, rather than optimizing the microlattice topology, we explore a different approach to strengthen low-density structural materials by designing tube-in-tube beam structures. We develop a process to transform fully dense, three-dimensional printed polymeric beams into graphitic carbon hollow tube-in-tube sandwich morphologies, where, similar to grass stems, the inner and outer tubes are connected through a network of struts. Compression tests and computational modelling show that this change in beam morphology dramatically slows down the decrease in stiffness with decreasing density. In situ pillar compression experiments further demonstrate large deformation recovery after 30–50% compression and high specific damping merit index. Lastly, our strutted tube-in-tube design opens up the space and realizes highly desirable high modulus–low density and high modulus–high damping material structures.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Enhanced pool boiling heat transfer with metal foam tubes in inline tube bundle configuration

Flooded evaporators, commonly known as shell-and-tube heat exchangers, are widely used in large-scale industrial refrigeration and air-conditioning systems due to their high pool boiling heat transfer efficiency. However, their bulky configuration requires a large refrigerant inventory, which poses safety challenges—particularly when employing next-generation A2L refrigerants that are mildly flammable. Here, to address this issue, the development of compact heat exchangers with enhanced heat transfer performance is essential. In this study, a novel metal foam tube design is proposed to augment pool boiling heat transfer. Experiments were conducted at a saturation temperature of 20 °C and across a heat flux range of 7–60 kW m −2 . The tests were conducted for both smooth and metal foam tubes with an inline tube bundle configuration and for a pitch–to–diameter (P/D) ratios of 1.3 and 1.5. Pool boiling performance was evaluated for next-generation hydrofluoroolefin (HFO) refrigerants, R1234yf and R1234ze(E), with R134a serving as the baseline fluid. The results indicate that the heat transfer coefficient (HTC) of R1234yf is comparable to R134a, while R1234ze(E) shows slightly lower performance. Importantly, the metal foam tubes achieved up to a 217% enhancement in HTC compared to smooth tubes.

Metal foam tubes↗
DOE OSTI2018

Adapted tube cleaning practices to reduce particulate contamination at hydrogen fueling stations

The higher rate of component failure and downtime during initial operation in hydrogen stations is not well understood. The National Renewable Energy Laboratory (NREL) has been collecting failed components from retail and research hydrogen fueling stations in California and Colorado and analyzing them using an optical zoom and scanning electron microscope. The results show stainless steel metal particulate contamination. While it is difficult to definitively know the origin of the contaminants, a possible source of the metal particulates is improper tube cleaning practices. To understand the impact of different cleaning procedures, NREL performed an experiment to quantify the particulates introduced from newly cut tubes. The process of tube cutting, threading and beveling, which is performed most often during station fabrication, is shown to introduce metal contaminants and thus is an area that could benefit from improved cleaning practices. This paper shows how these particulates can be reduced, which could prevent station downtime and costly repair. These results are from the initial phase of a project in which NREL intends to further investigate the sources of particulate contamination in hydrogen stations.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2018

Novel Capsule Fill Tube Assemblies for the Hydrodynamic Growth Radiography Targets

Capsule Fill Tube Assemblies (CFTAs) consist of an ablator capsule and fill tube via a laser drilled funnel hole. This hole then tapers from 17 μm diameter at the outer surface of the ablator capsule to less than 5 μm diameter on the inside of the capsule over approximately 200 μm of wall thickness. Demand for better understanding of the fill tube perturbation during the capsule implosion has driven advancements in the fill tube design. Engineering efforts have been made on Hydrodynamic Growth Radiography Assemblies (HGRs) using multiple tube design variations, including alternative angles, depths, sizes, and location with engineered defects to showcase fill tube effects during an implosion. Furthermore, testing has shown that these CFTAs and HGRs have survived all fabrication and transport to from General Atomics to Lawrence Livermore National Laboratory. These assemblies have also passed cryogenic testing at General Atomics. An overview of alternative CFTA designs, fabrication methods and developments will be presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Penetration of Ar and He RF-driven plasma jets into micrometer-sized capillary tubes

The penetration and propagation of cold atmospheric pressure plasmas into volumes having sub-millimeter to micrometer sizes with large aspect ratios is required for enabling an effective disinfection of the inside of catheter tubes, tooth cavities, skin pores and enhance plasma catalysis in porous catalysts. Here, we report on a study using a low voltage RF driven argon and helium plasma jets with the plasma generation outside a capillary tube with a large aspect ratio followed by its penetration and propagation inside the capillary. We present the experimental determination of the limitations on the penetration diameter, and the underpinning mechanisms of the plasma propagation and penetration process. Experimental results include time resolved imaging of plasma propagation and penetration in capillaries with different internal diameter and surface electric field measurements. We found that the time between the plasma jet in first contact with the capillary tube surface and the subsequent penetration into the capillary tube spans several RF cycles due to electric fields at the plasma-tube interface below 4 kV cm –1 . These low electric fields require Penning ionization and/or stepwise ionization and hence a buildup of the metastable and electron density is required to achieve a sufficiently large ionization rate near the capillary tube inlet to enable penetration and propagation. Furthermore, it is found that the propagation of the argon jet into the capillary occurs during the positive half cycle of the RF waveform and is very similar to the propagation of the jet in surrounding air.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

The Effect of Antiphase Boundary Tubes on the Hardness of FeAl

The high work hardening rate unique to ordered intermetallic alloys has long been attributed to antiphase boundary (APB) tubes. In this work, APB tubes are introduced in Fe–40 at. pct Al and Fe–43 at. pct Al by cold-rolling and then removed by annealing. The presence and absence of APB tubes is verified with magnetic measurements. When APB tubes are annealed out the hardness does not change, thus indicating that APB tubes do not contribute to strengthening.

36 MATERIALS SCIENCE↗