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Results for “diffusivity”

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 1,459 records · Page 81
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Monitoring of Unvented Roofs with Fibrous Insulation, Diffusion Vents, and Interior Vapor Control in a Cold Climate

Unvented roof assemblies have been accepted in North American building codes since 2007; code-compliant construction calls for a minimum thickness of “air-impermeable insulation” (based on climate zone) to avoid cold-weather condensation and moisture risks. This is typically implemented with polyurethane spray foam insulation; however, negatives of this material include high first cost and possible adverse environmental impacts. Implementing unvented roofs in a moisture-safe manner with air-permeable fibrous fill insulations (e.g., fiberglass or cellulose) could potentially reduce the first cost of unvented roof designs, allowing for more widespread use. Building unvented roofs in a cost-effective, airtight, and moisture-safe manner opens up options for high-performance house designers and builders.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Optimal Header Design for Diffusion Bonded Heat Exchangers

Microchannel heat exchangers have seen increasing adoption in many high-pressure applications in recent decades but are subject to particulate fouling from the relatively small channel size compared to traditional designs. Typical cleaning methods require process shutdown, heat exchanger removal, cleaning, then reassembly. The objective of this project was to refine and transfer technology to enable header design improvements for Cleaning-in-Place (CIP), allowing for reduced/negligible process interruption for the cleaning process. The technology transfer was from Sandia National Laboratories (Sandia) to Vacuum Process Engineering, Inc. (VPE). This primary purpose of CIP was developed while considering channel flow uniformity and heat exchanger cost. The project phases were to 1) capture and define potential improvement options, 2) evaluate options with both simulation and experiments, and 3) transfer design knowledge to the industry partner. These efforts resulted in improved header designs from the first known focused effort in this area. The improved designs will help the entire microchannel heat exchanger field that has applications in supercritical CO 2 power cycles, hydrogen (fuel cell) vehicle fueling, liquified natural gas processing, and more.

42 ENGINEERING↗
DOE OSTI2023

Storage and Diffusion of Carbon and Nitrogen in Crustal Materials

Nitrogen is a primary constituent of Earth’s atmosphere and an essential component of many biological processes. Recent developments in understanding N incorporation into silicate minerals suggest that the solid earth and lithosphere could provide a substantial reservoir for the planetary N budget. Furthermore, determining the concentration and distribution of low abundances of N in silicates presents a significant challenge in microanalysis. We tested capabilities for high spatial resolution quantification of low levels of N using EPMA with the goal of developing standards to be used in coupled N and noble gas analyses of silicate minerals. We investigated the concentration and distribution of N in a suite of ammonium-bearing silicate minerals that reflect the dominant N-bearing phases of the lithosphere: tobelite, buddingtonite, ammonioleucite, tsaregorodtsevite, and hyalophane. These minerals form during NH 4 -rich alteration of K-bearing silicate minerals, and the bonding environment of N in each mineral is likely to differ based on crystal structure. Using an optimized analytical routine for N quantification enables sensitivity approaching 0.02 weight% N and high-resolution quantitative mapping of sub-micron variations in N contents.

58 GEOSCIENCES↗
DOE OSTI2022

Exponential integrators for non-linear diffusion

The goal of this project is to compare the performance of exponential time integrators with traditional methods such as diagonally implicit Runge-Kutta methods in the context of solving the system of reduced magnetohydrodynamics (RMHD). In this report, we present initial results of a proof of concept study that shows that exponential integrators can be an efficient alternative to traditional integration schemes.

42 ENGINEERING↗
DOE OSTI2022

CalTestBed - Opus 12 - Study of Diffusion Media and Polymer Electrolyte Materials in Devices for CO2 to Fuels (CRADA Final Report)

Capturing carbon dioxide is one of the great ways to reduce the CO2 in the atmosphere while providing valuable renewable energy. Opus 12 is a Cyclotron Road startup using a membrane-electrode assembly (MEA) design. LBNL helped Opus 12 optimize its MEA design in this project through materials characterization and in situ studies. The finding of this project was used to develop a set of ideas for their MEA improvement under different operating conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗