Comprehensive study on nanofluid and ionanofluid for heat transfer enhancement: A review on current and future perspective

Thermal conductivity is a key parameter for thermal design and management of the electronic components in their passive cooling processes. In this work, thermal and electrical conductivities of six groups of binary Mg alloys (Mg–Al, Mg–Zn, Mg–Sn, Mg–Zr, Mg–Mn, and Mg–Ca) in as-cast, as-solution, and annealed states were measured and the corresponding microstructures were observed. In both as-cast and as-solution states, thermal/electrical conductivities of the six groups of Mg alloys decreased with composition. Effects of solution treatment and annealing on thermal/electrical conductivities of the as-cast samples were also investigated and discussed. Moreover, the specific thermal/electrical resistivity (thermal/electrical resistivity increment of the alloy derived from one atom addition) of the solute elements for Mg alloys was drawn as follows, Zn < Al < Ca < Sn < Mn < Zr. Atomic volume difference of the solute elements with Mg atom (ΔV/V
 Mg), valency, and configuration of extra-nuclear electron of the solute were believed as the main reasons for the differences.

Thermal and electrical conductivity of binary magnesium alloys

Effect of non-covalent functionalisation on thermal and mechanical properties of graphene-polymer nanocomposites

Experimental Investigations of Heat Transfer Mechanisms of a Pulsating Heat Pipe

Comparison and optimization of single-phase liquid cooling devices for the heat dissipation of high-power LED arrays

Heat dissipation design and analysis of high power LED array using the finite element method

Design of fins with a grooved heat pipe for dissipation of heat from high-powered automotive LED headlights

The thermal management of microelectronics has become a critical issue in Microsystems and optoelectronic industries. This is particularly evident with the development of high power density and high heat flux in MEMS, IC, and LED components and devices, which has further increased the demand for materials with high thermal performance. To enhance the performance of current thermal modules, the development of advanced materials to replace conventional monolithic materials is crucial. The energy storage characteristics exhibited by materials during phase change helps them to maintain a constant temperature and conserve energy. Microencapsulation is the technique of enclosing phase change materials within a high polymer shell to form microcapsules, called microencapsulated phase change materials (MPCMs). Mixing MPCMs into matrix materials makes it possible to control the temperature of systems. This study evaluates the thermal performance of an MPCM (manufactured as powder with 10–30 μm size) mixed substrate, and results show that the manufacturing process does not destroy the structure of MPCM. The time required for a substrate mixed with MPCM to reach thermal steady state was delayed, compared to the time required for substrates without MPCM. The higher the percentage of MPCM, the longer it took to reach steady state. In addition, the heat transfer efficiency of the MPCM in its solid state was lower than in its liquid state. This heat transfer behavior was quite different from that found in bulk-size materials. These results suggest the application of MPCM for the thermal control of microelectronics, thermal management of modern Microsystems technologies, and the conservation of green house energy.

The thermal evaluation of the substrate mixed with microencapsulated phase change materials for MEMS packaging applications

This study was to design and develop the efficient heat dissipation methods for light emitting diode (LED). There are two major achievements in the study: (1) Chips level: Improve the LED packaging materials and layers assembly of LED. This novel design was to introduce additional thin copper layer materials on LED base assembly with geometry that can reduce thermal resistance and increase thermal diffusion efficiency. The design was then being calculated on its heat transfer behavior using simulation with 3-D finite element method. The experimental and simulation results of various packaging area parameters were presented with respect to 0.75W, 1W and 3W LED chips. Both experimental and simulation results show close agreement that through the design of additional packaging arrangement it can reduce the thermal equilibrium temperature of LED. It was found that the addition of 9cm2 copper-packaged area improves the thermal dissipation of LED, resulting in a reduction of chip temperature lower 5°C than non-packaging pattern. (2) System level: Design and develop heat pipe structures as heat sink for a LED illuminator set. The experiments were conducted to investigate the cooling characteristics of heat pipes by changing working fluid mass and working angle. Additionally, both discrete hotspot of LED and central heating of heat pipe were studied. The results of heat pipe experiments show that when the experimental set of LED illuminator was used in horizontal angles, resulting in the heat pipe which fills 2.52g water volume has the best thermal properties than others. Resulting in the heat source temperature maintain in 50°C. Whereas others have higher temperature results due to the steam inside pipe choked. The experiment and simulation results show in this study provide very useful contributions for the application of heat dissipation for LED both in chip level packages and system level performance.

Heat dissipation performance for the application of light emitting diode

As the need for speed and precision in modern manufacturing technologies increases, linear motors are attracting considerable research attention. Heat management and thermal deformation associated with linear motors comprise a major concern tied to the demand for machining accuracy. Here we describe a three-dimensional finite-element simulation analysis method that utilizes a three-phase linear synchronous motor for thermally characterizing a feed-driven system. We also present results from simulations and experiments aimed at verifying system thermal time constants and temperature distributions. These results demonstrate that the proposed analytical method is capable of making accurate and useful predictions of temperature and thermal behavior distributions for linear motors in terms of conventional heat generation in various transient and steady-state phases. It is our hope that these results will support future efforts to design modern feed-driven systems equipped with linear motors.

De-Shau Huang

Papers

Heat dissipation design and analysis of high power LED array using the finite element method

Design of fins with a grooved heat pipe for dissipation of heat from high-powered automotive LED headlights

The thermal evaluation of the substrate mixed with microencapsulated phase change materials for MEMS packaging applications

Heat dissipation performance for the application of light emitting diode

Three-Phase Linear Motor Heat Transfer Analysis Using the Finite-Element Method