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Introduction to Electronic Cooling
Published in Mathew V. K., Tapano Kumar Hotta, Hybrid Genetic Optimization for IC Chips Thermal Control, 2022
Mathew V. K., Tapano Kumar Hotta
Most of the consumer-based electronic products and low-end applications of electronics deal with heat dissipation in the form of natural convection and surface radiation. However, natural convection has an edge over radiation due to its low operating cost, high system reliability, and noise-free operation. Here, the buoyancy forces due to the density difference cause the fluid movement. Natural convection cooling is characterized by non-dimensional parameters like Grashof number (Gr) and Rayleigh number (Ra). However, for higher cooling rates of the electronic components, natural convection air cooling is not preferred as a result of which, forced convection air cooling is achieved using external means like a fan or blower. Here the buoyancy forces are negligibly small. The forced convection cooling is characterized by Reynolds number (Re).
Thermal Management of Switched Reluctance Machines
Published in Berker Bilgin, James Weisheng Jiang, Ali Emadi, Switched Reluctance Motor Drives, 2019
Yinye Yang, Jianbin Liang, Elizabeth Rowan, James Weisheng Jiang
The transfer of heat generated within an SRM to an external heat sink depends on various factors, such as the mode of heat transfer, the effective heat transfer area and geometry, the working fluid used for cooling, the flow rate, and temperature of the cooling media. The simplest cooling technique is dissipating the heat to ambient by natural convection. Typically, the heat dissipation can be improved by increasing the heat transfer surface area with added fins on the housing. A more complicated forced air-cooling system can be used to further increase the heat dissipation. For example, a shaft mounted fan can be employed to enhance the heat transfer from the housing fins, the end windings, and rotor surfaces. However, for high current densities, using air as the cooling fluid may not be sufficient, and some form of liquid cooling may be required for better removal of heat. Typical rules of thumb for cooling techniques and associated heat transfer coefficients are listed in Table 14.1 [12]. Higher heat transfer coefficients enable higher current density and, hence, higher machine output power; however, at the expense of higher system complexity and energy cost.
Thermal Analysis
Published in Xiaolin Chen, Yijun Liu, Finite Element Modeling and Simulation with ANSYS Workbench, 2018
Problem Description: Heat sinks are commonly used to enhance heat dissipation from electronic devices. In the case study, we conduct thermal analysis of a heat sink made of aluminum with thermal conductivity k = 170 W/(m · K), density ρ = 2800 kg/m3, specific heat c = 870 J/(kg · K), Young's modulus E = 70 GPa, Poisson's ratio ν = 0.3 and thermal expansion coefficient α = 22 × 10−6/°C. A fan forces air over all surfaces of the heat sink except for the base, where a heat flux q’ is prescribed. The surrounding air is 28°C with a heat transfer coefficient of h = 30 W/(m2 · °C). (Part A): Study the steady-state thermal response of the heat sink with an initial temperature of 28°C and a constant heat flux input of q’ = 1000 W/m2. (Part B): Suppose the heat flux is a square wave function with period of 90 seconds and magnitudes transitioning between 0 and 1000 W/m2. Study the transient thermal response of the heat sink in 180 seconds by using the steady-state solution as the initial condition. (Part C): Suppose the base of the heat sink is fixed. Study the thermal stress response of the heat sink by using the steady-state solution as the temperature load.
Thermally conductive adhesives from covalent-bonding of reduced graphene oxide to acrylic copolymer
Published in The Journal of Adhesion, 2019
Minh Canh Vu, Young Han Bae, Min Ji Yu, Won-Kook Choi, Md. Akhtarul Islam, Sung-Ryong Kim
In the last decades, there have been revolutionary changes in the electronic and communication industries. Today the products of these industries serve many elements of human civilization, from large-scale industries to individuals. Along with that, there has been a dominating trend in these industries towards the miniaturization of their products. Integrated circuit chips (ICC) in miniature form, however, perform multi-functions compared to the previous generation ICC and consume electrical energy at a much higher rate. Thus, the rate of heat generation increases in a highly densed electronic devices demanding thermal management with high rate of heat-dissipation to heat sinks.[1] Failure to rapid heat-dissipation threatens the longevity and in some cases, reliability of the components.
An Experimental Investigation on Thermal Performance of Ultra-Thin Heat Pipes with Superhydrophilic Copper Braids
Published in Heat Transfer Engineering, 2021
Hui-Chung Cheng, Te-Hsuan Chen, Hsu-Sheng Huang, Ping-Hei Chen
By packing more transistors in an integrated circuit (IC), electronic products such as mobile devices, computers, and consumer electronics have become increasingly thinner, lighter, and better performing. However, under this trend of component miniaturization and higher efficiency, a heat dissipation problem occurs in ICs because more heat is generated in a smaller space. Without proper techniques for heat dissipation, operational efficiency decreases, malfunctions are more likely, and the product lifetime is shortened. Therefore, the thermal management of all crucial electronic components should be a key consideration in the design of electronic devices. Consequently, many heat dissipation mechanisms have been developed and investigated to improve thermal management in electronic devices. In small electronic devices, the cooling space is limited. To deal with the problem of high heat flux in a restricted space, ultra-thin heat pipes (UTHPs) have become an important component in cooling systems. Due to the phase change of the working fluid in the heat pipe, the latent heat can be used to dissipate large amounts of concentrated heat in a short time; a heat pipe’s heat transfer coefficient is at least ten times larger than that of natural convection [1]. The heat pipe comprises the container, working fluid, and wick structure. The container is typically made from a metal, such as copper and aluminum, due to their high strength and conductivity [2]. Working fluids typically have a high surface tension, high thermal conductivity, and low viscosity [3]. The wick structure provides the capillary force for the working fluid [4, 5]. Because the quality of the wick greatly affects the heat transfer efficiency of a heat pipe, wick structure design is important.
Benzoxazine-epoxy thermosets with smectic phase structures for high thermal conductive materials
Published in Liquid Crystals, 2019
Ying Liu, Sheng Gao, Xinjian Gong, Qingbin Xue, Zaijun Lu
Today, electronic devices are moving toward miniaturization, integration, and high power density. The heat accumulation problem is becoming more and more prominent. Effective heat dissipation has become one of the most important factors in improving the reliability and service life of electronic devices. However, the most heat-resistant polymers used in electronic devices have low thermal conductivity (TC). Therefore, it is highly necessary to develop a heat-resistant polymer having high TC.