Philip D. Myers

Molten Salt Spectroscopy for Quantification of Radiative Absorption in Novel Metal Chloride-Enhanced Thermal Storage Media

This study describes the development and characterization of novel high-temperature thermal storage media, based on inclusion of transition metal chlorides in the potassium–sodium chloride eutectic system, (K–Na)Cl (melting temperature of 657 � C, latent heat of 278 J/g). At the melting temperature of (K–Na)Cl, infrared (IR) radiation can play a major role in the overall heat transfer process—90% of spectral blackbody radiation falls in the range of 2–13lm. The authors propose inclusion of small amounts (less than 0.2 wt.%) of IR-active transition metal chlorides to increase radiative absorption and thereby enhance heat transfer rates. A new IR-reflectance apparatus was developed to allow for determination of the spectral absorption coefficient of the newly formulated phase-change materials (PCMs) in the molten state. The apparatus consisted of an alumina crucible coated at the bottom with a reflective (platinum) or absorptive (graphite) surface, a heated ceramic crucible-holder, and a combination of zinc sulfide (ZnS) and zinc selenide (ZnSe) windows for containment of the salt and allowance of inert purge gas flow. Using this apparatus, IR spectra were obtained for various transition metal chloride additives in (K–Na)Cl and improved IR activity, and radiative transfer properties were quantified. Further, thermophysical properties relevant to thermal energy storage (i.e., melting temperature and latent heat) are measured for the pure and additive-enhanced thermal storage media. [DOI: 10.1115/1.4029934]

Modeling friction factor in pipeline flow using a GMDH-type neural network

Abstract The standard methods of calculating the fluid friction factor, the Colebrook–White and Haaland equations, require iterative solution of an implicit, transcendental function which entails high computational costs for large-scale piping networks while introducing as much as 15% error. This study applies the group method of data handling to the development of an artificial neural network optimized by multi-objective genetic algorithms to find an explicit polynomial model for friction factor. We developed a relatively simple and explicit model for friction factor that performs well over the entire range of applicability of the Colebrook–White equation: Reynolds number from 4,000 to 108 with relative roughness ranging from 5 × 10−6 to 0.05. For a network with only two hidden layers and a total of five neurons, this model was found to have a mean relative error of only 3.4% in comparison with the Colebrook–White equation; a determination coefficient (R2) over the range of input data was calculated to be 0.9954. The accuracy and simplicity of this model may make it preferable to traditional, transcendental representations of fluid friction factor. Further, this method of model development can be applied to any pertinent data-set—that is to say, the model can be tuned to the physical situation and input data range of interest.

Development of Mold Compounds With Ultralow Coefficient of Thermal Expansion and High Glass Transition Temperature for Fan-Out Wafer-Level Packaging

Coefficient of thermal expansion (CTE) mismatch between an underfill encapsulant material and integrated circuit chips mounted on a substrate is the major reason for device failure in a fan-out wafer-level packaging (FOWLP) assembly. In this paper, a variety of moldable polymer composite systems with evenly dispersed dielectric nanoparticles or microparticles and minimal cure shrinkage for FOWLP assemblies have been investigated. Most importantly, a low CTE of 6.6 ppm/°C and a high glass transition temperature (Tg) above 300 °C were achieved through a processing methodology that exhibits fairly good repeatability. A special surfactant treatment of the particle surfaces has played a crucial role in further enhancing the thermomechanical properties, yield, and repeatability of the composite material.

Chloride Salt Systems for High Temperature Thermal Energy Storage: Properties and Applications

There is substantial potential to increase the operating temperatures of concentrating solar power (CSP) plants, thereby increasing the Carnot efficiency. Coupled with viable thermal energy storage (TES) strategies, this would bring us closer to achieving the goals of the U.S. Department of Energy Sunshot Initiative. Current TES media employ molten inorganic salts (namely, nitrate salts) for thermal storage, but they are limited in application to lower temperatures: generally, below 600°C. While sufficient for parabolic trough power plants, these materials are inadequate for use with the higher operating temperatures achievable in solar power tower-type CSP plants. For these higher temperatures, chloride salts are more ideal candidate storage media, either for sensible heat storage in the molten salt (e.g, a dual-tank storage arrangement) or for sensible and latent heat thermal energy storage (LHTES) as phase change materials (PCMs). Their melting points and those of their eutectic mixtures cover a broad range of potential operating temperatures, up to and including 800.7°C, the melting point of pure NaCl.This paper examines these salt systems and presents relevant properties and potential applications in high temperature (>400°C) utility scale solar thermal power generation. A preliminary screening of pure chloride salts based on available literature yields a list of promising candidate salts. Eutectic mixtures of these salts are also considered; the eutectic systems were modeled using the thermodynamic database software, FactSage. Thermophysical properties (melting point, latent heat) are summarized for each salt system. Radiative properties are also addressed, since at these temperatures, thermal radiation can become a significant mode of heat transfer. Candidate containment materials and strategies are discussed, along with the attendant potential for corrosion. Finally, cost data for these systems are presented, allowing for meaningful comparison among these systems and other materials in the context of utility scale thermal energy storage units.Copyright