Thermal modeling with solid/liquid phase change of the thermal energy storage experiment
A thermal model which simulates combined conduction and phase change characteristics of thermal energy storage (TES) materials is presented. Both the model and results are presented for the purpose of benchmarking the conduction and phase change capabilities of recently developed and unvalidated microgravity TES computer programs. Specifically, operation of TES-1 is simulated. A two-dimensional SINDA85 model of the TES experiment in cylindrical coordinates was constructed. The phase change model accounts for latent heat stored in, or released from, a node undergoing melting and freezing.
Startup Modeling of the Receiver of NASA' s 2-Kilowatt Solar Dynamic Power System
A simplie ed approach to predict the thermal startup transient of the receiver of NASA’ s experimental 2-kW solar dynamic (SD) system, designed for the generation of power in space, is presented in this paper. This system is being tested at the NASA Lewis Research Center (NASA‐LeRC) under low-Earth-orbit simulated conditions as part of the SD ground test demonstration program, which aims to address technology issues, develop experience, and validate theoretical models for future use of solar dynamic technology in space. One important technical issue being studiedisthetheoreticalmodeling ofthetransient-modeperformanceofSDsystems,whichhasdirectimpact on off-design operation and control in an Earth-orbital environment. Preliminary correlation between experiment and existing theoretical predictions has suggested the need for improving existing models, such as the closed cycle engine program (CCEP), an in-house NASA computer code. Computational predictions based on the theoretical modelpresented in this papershowsignie cantimprovement in regardto startup receiverperformance. To validate this model, comparisons between the experimental results obtained from the tests performed at the NASA ‐LeRC, and the computational predictions, are presented and discussed. The predictions of the simplie ed model show a close match with experimental results for values of solar energy near those reported in the experimental tests. Some predictions from the CCEP and pertinent discussion are also presented.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).