Gregory Nellis
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View article: Low-Cost Heliostat for High-Flux Small-Area Receivers (Final Technical Report)
Low-Cost Heliostat for High-Flux Small-Area Receivers (Final Technical Report) Open
This project analyzed a two-stage heliostat concept consisting of a tracking stage and a concentrating stage. The tracking stage uses mirrors mounted on a common drive that move to track the sun. The concentrating stage consists of station…
View article: Further experimental work in mixed gas Joule-Thomson cryocooling
Further experimental work in mixed gas Joule-Thomson cryocooling Open
Miniature Joule-Thomson (JT) cryocoolers are attractive for many applications due to their small size and resulting fast cool-down time. Finned-tube heat exchangers are one of the most widely used heat exchanger for miniature JT cryocooler…
View article: Static friction testing of various materials in liquid nitrogen
Static friction testing of various materials in liquid nitrogen Open
The Deep Underground Neutrino Experiment will utilize charge readout planes (CRPs) that are submerged within liquid argon. These charge readout planes are part of a drift detector used measure the cascade of charged particles generated by …
View article: Characterization of the thermal properties of OFHC copper at cryogenic temperature
Characterization of the thermal properties of OFHC copper at cryogenic temperature Open
Advancements in electronics technology that operate at cryogenic temperature require the study of thermal properties of the materials and interfaces used to connect these systems to a source of cooling. A test facility has been developed t…
View article: Liquid-Film Flow Rate From Measurements of Disturbance Wave Characteristics for Applications in Thin Film Flow
Liquid-Film Flow Rate From Measurements of Disturbance Wave Characteristics for Applications in Thin Film Flow Open
This paper discusses the development of a liquid-film thickness measurement technique using laser refractometry and the extension of this technique to enable the measurements of wave height, shape, frequency and velocity. The measurement t…
View article: 3D structures and methods therefor
3D structures and methods therefor Open
Aspects of the disclosure are directed to methods and/or apparatuses involving one or more of a conductive polymer, deposition of a conductive polymer and 3D (three-dimensional) printing of a continuous bead of material. As may be implemen…
View article: Forced Convection Heat Rejection System for Mars Surface Applications
Forced Convection Heat Rejection System for Mars Surface Applications Open
A forced convection heat exchanger for waste heat rejection to the Martian atmosphere is designed based on existing heat transfer and pressure drop correlations for low-Reynolds-number finned tube arrays. The design is optimized to determi…
View article: Influence of winding topologies and encapsulation materials on FSPM machine thermal performance
Influence of winding topologies and encapsulation materials on FSPM machine thermal performance Open
This study investigates the thermal impact of using different winding topologies and different winding encapsulation materials on dual‐stator 6/4 flux‐switching permanent magnet (FSPM) machine with water jacket cooling. The thermal perform…
View article: Experimental validation and refinement of mixture optimization for a mixed gas Joule-Thomson cycle
Experimental validation and refinement of mixture optimization for a mixed gas Joule-Thomson cycle Open
An initial prototype of a mixed gas Joule-Thomson (JT) cryocooler was constructed and installed in a test facility to experimentally validate and refine a computational tool developed to optimize the gas mixture composition for a Joule-Tho…
View article: Data for: Modeling and Experimental Testing of Periodic Flow Regenerators for sCO2 Cycles
Data for: Modeling and Experimental Testing of Periodic Flow Regenerators for sCO2 Cycles Open
This file gives all of the temperature, pressure, and mass flow measurements averaged for one cycle under constant test conditions. Each of the runs is on a different tab of the document.
View article: Supercritical Brayton Power Conversion with a Direct Cooled Reactor for Space Power
Supercritical Brayton Power Conversion with a Direct Cooled Reactor for Space Power Open
To achieve future goals in space exploration a long life, compact power system will be necessary, and nuclear power sources are a promising option. The goal of this project is to achieve mass optimization with a supercritical Brayton Cycle…
View article: Advanced Air-Side Heat Transfer Surface Geometries Enabled by Additive Manufacturing
Advanced Air-Side Heat Transfer Surface Geometries Enabled by Additive Manufacturing Open
In a world with a decreasing supply of fresh water, industry is looking for design solutions that depend less on the availability of water. Dry-cooled condensers are one possibility, but they must compete with traditional water-cooled cond…
View article: Additive Manufacturing of Heat Exchangers
Additive Manufacturing of Heat Exchangers Open
The Advanced Research Project Agency (ARPA) includes the Advanced Research In Dry cooling (ARID) program. The objective of the ARID program is to develop technologies that allow power plants to achieve high thermal-to-electric energy conve…
View article: Mixture optimization for mixed gas Joule-Thomson cycle
Mixture optimization for mixed gas Joule-Thomson cycle Open
An appropriate gas mixture can provide lower temperatures and higher cooling power when used in a Joule-Thomson (JT) cycle than is possible with a pure fluid. However, selecting gas mixtures to meet specific cooling loads and cycle paramet…
View article: Detailed energy model of the National Institute of Standards and Technology Net-Zero Energy Residential Test Facility: Development, modification, and validation
Detailed energy model of the National Institute of Standards and Technology Net-Zero Energy Residential Test Facility: Development, modification, and validation Open
The NIST Net-Zero Energy Residential Test Facility (NZERTF) is a highly instrumented, highly configurable, single-family, net-zero energy house occupied by a virtual family of four. A detailed transient model of the NZERTF and the accompan…