Search NASA⌕ Search

SEARCH · Search NASA

Results for “PIPES”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

A Simplified Model of VIPER Thermal Management System. Part I: Loop Heat Pipe

NASA’s Volatiles Investigating Polar Exploration Rover (VIPER) uses a combination of loop heat pipes (LHPs) and heaters as the primary hardware to modulate the temperature of the electronic boxes and payloads instruments. LHPs have been designed and instrumented to be capable of passive and active shutdown. The goal of the passive shutdown, using a thermal control valve (TCV) to limit the flow of the working fluid, is to preserve thermal energy and avoid unnecessary heat leaks during lunar night. The goal of the active shutdown on the other hand, is to forcefully increase the vehicle internal temperature to bakeout the payload instruments. Several numerical modeling tools are available to analyze LHP performance under the complex set of operational requirements and environments levied on the VIPER Thermal Management System (TMS). Yet, while those numerical modeling tools are capable of detailed performance analysis, they tend to take large computational resources and long computational time. In this paper, a model of a single LHP developed based on control volume approach is presented. By using the control volume approach, the complex geometry of the LHP, and the components attached to it, are reduced to thermal lump capacitances, thus reducing the computation effort. This paper also describes the effort to correlate the proposed LHP model using thermal vacuum (TVAC) test data.

Loop Heat Pipe↗
NASA NTRSDate not supplied

A Simplified Model of VIPER Thermal Management System. Part I: Loop Heat Pipe

NASA’s Volatiles Investigating Polar Exploration Rover (VIPER) uses a combination of loop heat pipes (LHPs) and heaters as the primary hardware to modulate the temperature of the electronic boxes and payloads instruments. LHPs have been designed and instrumented to be capable of passive and active shutdown. The goal of the passive shutdown, using a thermal control valve (TCV) to limit the flow of the working fluid, is to preserve thermal energy and avoid unnecessary heat leaks during lunar night. The goal of the active shutdown on the other hand, is to forcefully increase the vehicle internal temperature to bakeout the payload instruments. Several numerical modeling tools are available to analyze LHP performance under the complex set of operational requirements and environments levied on the VIPER Thermal Management System (TMS). Yet, while those numerical modeling tools are capable of detailed performance analysis, they tend to take large computational resources and long computational time. In this paper, a model of a single LHP developed based on control volume approach is presented. By using the control volume approach, the complex geometry of the LHP, and the components attached to it, are reduced to thermal lump capacitances, thus reducing the computation effort. This paper also describes the effort to correlate the proposed LHP model using thermal vacuum (TVAC) test data.

Loop Heat Pipe↗
DOE OSTI2022

Silicon Carbide Multilayer Piping for High Temperature sCO 2 Brayton Cycle

Efficiencies of greater than 50% in supercritical carbon dioxide (sCO 2 ) Brayton power cycle systems can be achieved only at turbine inlet temperatures of above 700°C. In support of the push to higher temperatures, a finite element model was developed by Materials Research & Design, Inc. (MR&D) with support from Ceramic Tubular Products, LLC. (CTP) to guide the refinement of CTP’s high temperature ceramic multilayer piping. The multilayer technology combines the advantages of a monolithic silicon carbide (SiC) tube and a SiOC f /SiOC ceramic matrix composite (CMC), the result of which is a material with high-temperature strength and stability, high mechanical and thermal shock resistance, and high corrosion resistance. In addition to fabricating test specimens to refine the finite element model, long-duration, high temperature CO 2 exposure tests were performed by Sandia National Laboratories (SNL) on two varieties of inner monolithic SiC.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Decontamination Process of Internal Part Pipes - 13442

The Marcoule Site, created in 1955 is one of the first nuclear sites in France. It combines the activities of the Research Centre of the French Atomic Energy Commission (CEA) and AREVA industrial operations. Today, a large part of the operations on this site consists of the cleaning and the dismantling of nuclear Installations, once the end of their life cycle has been reached. An example can be the reprocessing plant UP1. This unit, started in 1958 has been stopped in 1997 and its dismantling started quickly thereafter. Technical challenges of the UP1 dismantling are mainly linked to a very high risk of exposure due to a large variety of contaminated equipments and residuals of fission products, potential sources of irradiation. The dismantling of Hall 71 is a typical example of such challenge. This paper will present a solution developed by AREVA Clean-Up business unit, in collaboration with COFIM Industry, to remove contamination incrusted inside the pipes before starting the cutting operations, thus reducing irradiation risk. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Operation and Security Considerations for Heat Pipe Cooled Microreactors

Microreactors and small modular reactors (SMRs) are anticipated to be key elements in the United States' carbon-free energy portfolio, serving as reliable power sources for remote communities, disaster relief zones, extraterrestrial deployments, and backup power needs. Microreactors employ technologies that are substantially more advanced and recent compared to conventional reactors. Furthermore, they are of a drastically smaller scale and are designed to be operated in a diverse set of locations, offering operational flexibility and mobility. In addition, the autonomous or semi-autonomous operation of microreactors with minimal or no on-site staff is anticipated. These factors give rise to specific challenges with regards to their safety and security. The present work investigates considerations related to heat pipe operation, reactor transport, and cyber/cyberphysical security to ensure the indirect and direct consequences of nefarious actors’ actions are understood and can be mitigated by design or through physical security measures. In addition, future directions are proposed for consideration by both HPMR designers and for regulators.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Heat Pipe Modeling with Sockeye

This presentation gives an overview of the models in the heat pipe code Sockeye, as well as the current status of its validation.

42 ENGINEERING↗
DOE OSTI2025

Heat Pipe Modeling Capabilities in Sockeye

Presentation to be given in a meeting with stakeholders of the Nuclear Energy Advanced Modeling and Simulation program for modeling related to microreactors. This presentation gives an overview of the capabilities and status of the heat pipe code Sockeye.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2026

Surrogates for Valve-Controlled Pipe Flow: Accelerating Nuclear Reactor Design

Neural surrogate models are developed to replace expensive steady-state RANS CFD simulations for valve-controlled pipe flow in nuclear reactor design. Using parametric CFD data generated with MOOSE Pronghorn across a range of valve geometry and flow conditions, three approaches are compared: a POD-based reduced-order model, a structured UNet on a cylindrical grid, and unstructured models (DeepONet and BiStride MeshGraphNet) on nondimensionalized point clouds. POD achieves the highest accuracy (99%) with fast inference but requires storing all solution snapshots, while the DeepONet and BSMS-GNN both achieve ~89% accuracy at sub-second inference, with the BSMS-GNN offering superior geometric generalizability. These surrogates enable rapid ranking of candidate valve designs and can warm-start CFD solvers to accelerate convergence, supporting agentic design iteration on the Prometheus platform.

42 - ENGINEERING↗
DOE OSTI2018

Effect of Tempered Martensite and Ferrite/Bainite on Corrosion Behavior of Low Alloy Steel Used for Flexible Pipe Exposed to High-Temperature Brine Environment

Immersion experiments and electrochemical measurements were carried out to study the effect of tempered martensite and ferrite/bainite on corrosion behavior of low alloy steel used for flexible pipe exposed to high-temperature brine environment in terms of microstructure morphology, corrosion rate, corrosion products characteristics, potentiodynamic polarization curves and electrochemical impedance spectroscopy. The experimental results indicated that the proportion of high-angle grain boundaries of tempered martensite steel was greater than ferrite/bainite steel. The corrosion rate of ferrite/bainite steel was lower than tempered martensite steel. With increasing immersion time, the structure of corrosion products formed on the surface of ferrite/bainite steel was more compact and denser than tempered martensite steel. In addition, the current density of ferrite/bainite steel was lower than tempered martensite steel. The charge transfer resistance and total impedance of ferrite/bainite steel were larger than tempered martensite steel. Thus, the corrosion resistance of ferrite/bainite steel exposed to high-temperature brine environment was excellent compared to the tempered martensite steel.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Corrosion Resistances of Steel Pipe Coated with Two Types of Enamel by Two Coating Processes

The corrosion behaviors of uncoated, enamel-coated, and epoxy-coated steel samples were evaluated in 3.5 wt.% NaCl solution with open-circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization tests. Two types of enamel (powder and slurry) were coated on steel samples in electrostatic and wet spraying processes, respectively. Twelve 25 mm × 25 mm steel samples were cut from an API 5L X65 pipe of 323.850 mm in outer diameter and 9.525 mm in wall thickness. They were divided into four groups of three identical samples. Each group represents one of the four conditions: uncoated, powder enamel-coated, slurry enamel-coated and epoxy-coated. Scanning electron microscopy images revealed that the powder and slurry enamel coatings were approximately 180 and 235 µm thick, respectively. The powder enamel coating has fewer but larger isolated pores than the slurry enamel coating. Electrochemical tests consistently indicated that the powder and slurry enamel coatings provided slightly better and worse corrosion protection to the coated steel samples, respectively, than the epoxy coating. The charge transfer resistances of all the coated samples are approximately 10{sup 8} times larger than that of the uncoated samples. All the coated samples were unlikely corroded within 2 h of immersion.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Asymptotic hydrogen redistribution analysis in yttrium-hydride-moderated heat-pipe-cooled microreactors using DireWolf

Yttrium hydride (YH x ) is one of the materials being considered for moderating thermal and epithermal nuclear microreactors. One potential issue with YH x use is that the hydrogen redistributes in the hydride when thermal and concentration gradients are present. This hydrogen redistribution leads to spatial gradients in the hydrogen concentration, thus affecting neutron transport in the reactor. Here, by building upon observations in prior works, this paper aims to gain a better understanding of the reactivity feedback associated with such hydrogen redistributions. In particular, we wish to understand the sign (+/–) of the hydrogen redistribution neutronic feedback, its order of magnitude, and its underlying physical causes. To achieve this goal, the DireWolf multiphysics software driver was used to solve the coupled radiation transport, heat transfer, heat pipe two-phase flow, and hydrogen redistribution equations for the Simplified Microreactor Benchmark Assessment (SiMBA) problem, a full-core microreactor numerical benchmark developed at Idaho National Laboratory.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2024

Autonomous control for Heat-Pipe microreactor using Data-Driven model predictive control

To enable a self-regulating capability for heat pipe (HP) microreactors, an anticipatory control strategy achieved via model predictive control (MPC) could proactively respond to potential disturbances and deviations in operating setpoints. This paper demonstrates data-driven methods for predicting the distribution and transient of temperatures and heat fluxes at selected components and regions in a 37-HP system, based on which the optimal control actions in response to changes in user-defined setpoints can be found. We present the development and validation of linear state-space model, feedfoward, and recurrent neural networks. Here, we compare the performance of MPCs with different modeling approaches in terms of following setpoints for temperatures and averaged output heat fluxes. The accuracies of the three data-driven models are similar, but the control actions initiated by neural-network-based MPC can better adapt to drastic changes in setpoints yet generate the smallest errors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

Hydrogen accelerated fatigue crack growth of friction stir welded X52 steel pipe

Friction stir welded steel pipelines were tested in high pressure hydrogen gas to examine the effects of hydrogen accelerated fatigue crack growth. Fatigue crack growth rate (da/dN) vs. stress-intensity factor range (ΔK) relationships were measured for an X52 friction stir welded pipe tested in 21 MPa hydrogen gas at a frequency of 1 Hz and R = 0.5. Tests were performed on three regions: base metal (BM), center of friction stir weld (FSW), and 15 mm off-center of the weld. For all three material regions, tests in hydrogen exhibited accelerated fatigue crack growth rates that exceeded an order of magnitude compared to companion tests in air. Among tests in hydrogen, fatigue crack growth rates were modestly higher in the FSW than the BM and 15 mm off-center tests. Select regions of the fracture surfaces associated with specified ΔK levels were examined which revealed intergranular fracture in the BM and 15 mm off-center specimens but an absence of intergranular features in the FSW specimens. In conclusion, the X52 friction stir weld and base metal tested in hydrogen exhibited fatigue crack growth rate relationships that are comparable to those for conventional arc welded steel pipeline of similar strength found in the literature.

08 HYDROGEN↗
DOE OSTI2026

Evaluating hydrogen permeation through medium-density and high-density polyethylene pipes to enable a hydrogen-compatible infrastructure

As the United States and the global community pursue energy abundance and resilience, hydrogen is becoming a critical energy carrier. The future of hydrogen transport depends on one thing: verifying that today’s pipelines are hydrogen ready. This study investigates the permeation behavior of medium-density polyethylene (MDPE) and high-density polyethylene (HDPE) pipelines under pure hydrogen gas environment at various pressures and temperatures. Using thermal desorption analysis (TDA) and direct pipe permeability measurements, hydrogen loss rates are quantified, revealing minimal permeation losses (< 10.5 g/km/day) under realistic operating conditions. Effects of temperature and pressure with Standard Dimension Ratios (SDR), were evaluated to determine their influence on permeation rates of MDPE and HDPE pipelines. In addition, ex-situ density and degree of crystallinity (DOC) of MDPE and HDPEs after hydrogen exposure were also investigated to understand pressure-dependency of polymer properties. The findings provide essential data for assessing polymer-based pipeline materials for safe and reliable hydrogen transport.

08 HYDROGEN↗