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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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Development and Validation of Resistance-Capacitance Model for Phase Change Material Embedded in Porous Media
A simple and effective way to enhance PCM thermal conductivity is by embedding porous materials with high thermal conductivities. In this work, CFD was used to evaluate the melting of PCM embedded in metal foam supplied with constant heat flux. Good agreement between experimental and numerical results has been found with a mean PCM local temperature deviation of 1.62K and 2.97K in two locations. The CFD simulation time was 56 hours for 6.5 hours of flow time. A computationally efficient resistance capacitance-based model (RCM) was developed to improve simulation speed. The proposed RCM exhibited mean local temperature deviations of 1.86K and 2.96K when compared against the experimental data for two thermocouple positions, however, it was approximately 2.5x10 5 times faster than CFD. The charging time deviation was less than 1% compared to CFD, and no significant change in thermal energy stored was observed since the temperature differences were small enough to result in insignificant sensible heat deviation. A simulation cost-effectiveness index (CEI) considering accuracy and computational affordability was introduced; the CEI of the RCM solver is 10 3 times better compared to CFD for the prediction of local PCM temperature.
Data-Driven Detection of Phase Changes in Evolving Distribution Systems.
Abstract not provided.
Programming active cohesive granular matter with mechanically induced phase changes
Interactions of simple robots can be mapped to a discrete algorithm that accurately predicts the ensemble’s emergent behaviors.
A New Approach for Liquid/Vapor Phase Change at Engine-Relevant Conditions.
Abstract not provided.
Data-Driven Detection of Phase Changes in Evolving Distribution Systems.
Abstract not provided.
Practical database enrichment strategies with iterative learning: Neural Network Potentials for Phase Change Memory.
Abstract not provided.
Probing Structural and Magnetic Phase Changes in the Shock Response of Iron with Molecular Dynamics.
Abstract not provided.
High-energy (MeV), heavy ion irradiation of chalcogenide phase change thin films.
Abstract not provided.
Online Data-Driven Detection of Phase Changes in Evolving Distribution Systems
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Phase change indicators for subambient temperatures
Evaluation of organic compounds for temperature indicators for subambient temperatures
Space thermal control by use of solid/solid- phase change materials Annual summary report, 25 Jun. 1968 - 24 Jul. 1969
Solid/solid-phase transition materials for use in passive thermal control
Solar powered absorption cycle heat pump using phase change materials for energy storage
Solar powered heating and cooling system with possible application to residential homes is described. Operating principles of system are defined and illustration of typical energy storage and exchange system is provided.
Feasibility study for automatic reduction of phase change imagery
The feasibility of automatically reducing a form of pictorial aerodynamic heating data is discussed. The imagery, depicting the melting history of a thin coat of fusible temperature indicator painted on an aerodynamically heated model, was previously reduced by manual methods. Careful examination of various lighting theories and approaches led to an experimentally verified illumination concept capable of yielding high-quality imagery. Both digital and video image processing techniques were applied to reduction of the data, and it was demonstrated that either method can be used to develop superimposed contours. Mathematical techniques were developed to find the model-to-image and the inverse image-to-model transformation using six conjugate points, and methods were developed using these transformations to determine heating rates on the model surface. A video system was designed which is able to reduce the imagery rapidly, economically and accurately. Costs for this system were estimated. A study plan was outlined whereby the mathematical transformation techniques developed to produce model coordinate heating data could be applied to operational software, and methods were discussed and costs estimated for obtaining the digital information necessary for this software.
Factors affecting phase-change paint heat-transfer data reduction with emphasis on wall temperatures approaching adiabatic conditions.
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An experimental and theoretical investigation of the liquefaction dynamics of a phase change material in a normal gravity environment
Experimental and theoretical investigations were undertaken to determine the role of gravity-induced free convection upon the liquefaction dynamics of a cylindrical paraffin slab under normal gravity conditions. The experimental equipment consisted of a test cell, a fluid-loop heating system, and a multipoint recorder. The test chamber was annular in shape with an effective radius of 1.585 cm and a length of 5.08 cm. The heating chamber was a 1.906 cm diameter tube going through the center of the test chamber, and connected to the fluid loop heating system. All experimental runs were made with the longitudinal axis of the test cell in the vertical direction to insure that convection was not a function of the angular axis of the cell. Ten melting runs were made at various hot wall temperatures. Also, two pure conduction solidification runs were made to determine an experimental latent heat of fusion.
Electron paramagnetic resonance studies of a viscous nematic liquid crystal. II - Evidence counter to a second-order phase change.
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