Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

/pdf/light-emitting-diodes-ubzde6g9qc.pdf

Light-emitting diodes

Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

A review of Ga2O3 materials, processing, and devices

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

The thermal anisotropy inherent in pin fins fabricated of polymer matrix composites necessitates the use of two-dimensional orthotropic relations for the prediction of the temperature distribution and heat transfer rate in large Biot number fins. Such fins offer a promising alternative to conventional metallic fins and heat sinks for electronic cooling applications, providing the benefits of moldability, lower density, lower fabrication energy and reduced cost. To realize these benefits and to compete favorably with the heat rejection capability of metallic fins and heat sinks, the polymer composite components must be thermally-optimized for the least-material configuration. This paper begins with a brief review of the available literature and a previously derived rigorous analytic model for orthotropic pin fins. The parametric trends are explored and attention is focused on identifying the least-material pin fin aspect ratio for a range of volumes and operating conditions. The orthotropic least-material configuration is found to closely approximate the aspect ratio associated with an isotropic fin. Simplified equations are proposed and analyzed for the cooling rate of an orthotropic pin fin. Further it is combined together with the least-material relation in order to design a least-material natural convection heat sink. The performance of the polymer least-material heat sinks is evaluated and compared, using common metrics, to conventional aluminum heat sinks

Analysis and Design of a Least Material Orthotropic Pin Fin Heat Sinks

Influence of chip/encapsulant delamination on the thermo-structural behavior of a thermally-pulsed plastic IC package

A coefficient of performance (COP/sub T/) analysis for plate fin heat sinks in forced convection is presented and shown to provide a viable technique for combining least-material optimization with the entropy minimization methodology. The COP/sub T/ metric relates the heat sink cooling capability to the invested fan pumping work and the thermodynamic work required to manufacture and assemble the heat sink. The proposed optimization methodology maximizes the forced convection cooling that can be achieved by a heat sink occupying a specified volume, with a fixed energy investment and entropy generation rate. In addition, the study identifies the presence of an optimal resource allocation ratio, providing the most favorable distribution of existing energy resources, between heat sink manufacturing and operation, over a fixed product life cycle.

https://ieeexplore.ieee.org/iel5/7908/21811/01012535.pdf

Least-energy optimization of forced convection plate-fin heat sinks

We investigated two phase heat transfer in staggered and inline micro pin fin arrays, using deionized water and HFE-7200 as working fluids with exit qualities up to 90%,. The inline and staggered arrays have equivalent pin fin width of 153μm and height of 305μm on a heated base area of 0.96cm width by 2.88cm length. Mass fluxes ranged from 200 kg/m2s to 600 kg/m2s for HFE-7200 and 400 kg/m2s to 1300 kg/m2s for water. Base heat fluxes ranged from 27 W/cm2 to 118 W/cm2 for water, and 1 W/cm2 to 36 W/cm2 for HFE-7200. Average heat transfer coefficient data were obtained and successfully correlated to 3% MAE for water and 10-13% MAE for HFE-7200 in these pin fin arrays.

http://ieeexplore.ieee.org/iel7/6882079/6892251/06892284.pdf

High vapor quality two phase heat transfer in staggered and inline micro pin fin arrays

An extensive numerical and experimental study of deep reactive ion etched (DRIE) thin film Pb(Zr,Ti)O3 (PZT) membranes used to enhance heat transfer between an immersed integrated circuit and a dielectric fluid is presented Modal and harmonic analysis of the vibrating PZT membranes was performed using finite element techniques for a frequency range from 0 to 5 MHz Experimental and numerical results showed that as the size of the PZT membranes increased, their fundamental resonance frequency decreased and they exhibited an increase in the number of resonance points in a given frequency range Square and rectangular PZT membranes showed similar resonant characteristics, while elliptic membranes displayed more resonant points than circular devices For a specified frequency range and equivalent surface areas, square membranes had more resonant points than circular membranes When the thin film PZT membranes are immersed in a dielectric fluid, substantial vortices and turbulences, along with distinct particle flow paths, were observed

https://iopscience.iop.org/article/10.1088/0964-1726/14/6/017/pdf

Avram Bar-Cohen

Papers

Analysis and Design of a Least Material Orthotropic Pin Fin Heat Sinks

Influence of chip/encapsulant delamination on the thermo-structural behavior of a thermally-pulsed plastic IC package

Least-energy optimization of forced convection plate-fin heat sinks

High vapor quality two phase heat transfer in staggered and inline micro pin fin arrays

Design, fabrication, and characterization of thin film PZT membranes for high flux electronics cooling applications