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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Development of Versatile Compressor Modeling using Approximation Techniques for Alternative Refrigerants Evaluation

Refrigerants are the life-blood of vapor compression systems that are widely used in Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R) applications. The HVAC&R community is currently transitioning from main-stream refrigerants that have high Global Warming Potential (GWP) to alternative lower-GWP refrigerants. During this transition, it is important to account for the life cycle climate performance of alternative refrigerants since their performance will be different than that of higher-GWP refrigerants. This requires the evaluation of the system performance with the new refrigerants. Unfortunately, it is extremely difficult to predict the realistic performance of new alternative refrigerants without experimental validation. One of the main challenges in this regard is modeling the compressor performance with high fidelity due to the complex interaction of operating parameters, geometry, boundary conditions, and fluid properties. High fidelity compressor models are computationally expensive and require significant pre-processing to evaluate the performance of alternative refrigerants. This paper presents a new approach to modeling compressor performance when alternative refrigerants are used. The new modeling concept relies on using existing compressor performance to create an approximate model that captures the dependence of compressor performance on key operating parameters and fluid properties. The model can be built using a myriad of approximation techniques. This paper focuses on Kriging-based techniques to develop higher fidelity approximate compressor models. Baseline and at least one alternative refrigerant performance data are used to build the model. The model accuracy was evaluated by comparing the model results with compressor performance data using other refrigerants. Preliminary results show that the approximate model can predict the compressor mass flow rate and power consumption within 5%.

Approximation↗
DOE OSTI2011

Robustness and Versatility of Thin Films on Low Temperature Cofired Ceramic (LTCC)

Thin film multilayers have previously been introduced on multilayer low temperature cofired ceramic (LTCC). The ruggedness of a multipurpose Ti-Cu-Pt-Au stack has continued to benefit fabrication and reliability in state-of-theart modules. Space optimization is described, preserving miniaturization of critical spaces and component pads. Additional soldering details are also presented, including trends with solder-stop materials. Feature compensation becomes a simple step in the normal manufacturing flow which enables exact targeting of desired feature sizes. In addition, fine details of the manufacturing process, including ion milling, will be discussed. We will discuss full long-term aging results and structural details that reinforce the reliability and function. Different thin film materials for specific applications can be exploited for additional capabilities such as filters and other integral components. Cross sections verify the results shown. This successful integration of thin films on LTCC points to higher frequencies which require finer lines and spaces. Advancements of these applications become possible due to the associated progression of smaller skin depth and thinner metallic material.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Development of Rhodobacter as a Versatile Microbial Platform for Fuels Production

The overall goal of the project was to genetically engineer the C30 triterpene hydrocarbons – squalene and botryococcene - in the heterologous host, Rhodobacter capsulatus. This host can grow autotrophically on CO 2 , H 2 and O 2 and there were indications of related species that could accept electrons directly from a cathode. Since water can be split into H 2 and O 2 by electrolysis, this provided alternative paths from renewable electrical energy to liquid fuels. The hydrocarbon target could not only provide a ‘drop in’ crude oil substitute, but its hydrophobicity would also provide ease of separation and thereby improve process economics over water miscible fuels such as ethanol. Combined with indications that Rhodobacter has a low baseline maintenance energy requirement, the research was focused on achieving economic feasibility through reduced process costs. This included an examination of bioreactor designs with low energy input for the delivery of the gases for consumption by the organism. The scope of the research therefore ranged from detailed process technoeconomic modeling, to metabolic engineering of the hydrocarbon biosynthetic pathways into Rhodobacter. The project demonstrated technical feasibility of producing triterpene hydrocarbons in Rhodobacter, and even some success in the acceptance of electrons by a consortium of bacteria from an electrode. However, the process economic models indicate that the rates of these biological processes are not yet sufficient to provide a fuel-producing process at typical costs of renewable energy generation such as solar photovoltaics. The project trained over 20 students in this highly interdisciplinary project context, with two of the students taking on faculty positions before the completion of the project.

10 SYNTHETIC FUELS↗
DOE OSTI2015

Versatile spin-polarized electron source

One or more embodiments relate generally to the field of photoelectron spin and, more specifically, to a method and system for creating a controllable spin-polarized electron source. One preferred embodiment of the invention generally comprises: method for creating a controllable spin-polarized electron source comprising the following steps: providing one or more materials, the one or more materials having at least one surface and a material layer adjacent to said surface, wherein said surface comprises highly spin-polarized surface electrons, wherein the direction and spin of the surface electrons are locked together; providing at least one incident light capable of stimulating photoemission of said surface electrons; wherein the photon polarization of said incident light is tunable; and inducing photoemission of the surface electron states.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗