Design of Thermal Ground Planes for Cooling of Foldable Smartphones

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Ali Nematollahisarvestani ◽  
Ryan J. Lewis ◽  
Yung-Cheng Lee
Keyword(s):  
Thermal Management ◽  
Temperature Difference ◽  
Ground Plane ◽  
Heat Sources ◽  
Heat Spreader ◽  
Fem Model ◽  
Graphite Sheet ◽  
Promising Solution ◽  
Graphite Heat ◽  
Near Future

Foldable smartphones are expected to be widely commercialized in the near future. Thermal ground plane (TGP), known as vapor chamber or two-dimensional flat heat pipe, is a promising solution for the thermal management of foldable smartphones. There are two approaches to designing a TGP for foldable smartphones. One approach uses two TGPs connected by a graphite bridge and the other approach uses a single, large, and foldable TGP. In this study, different thermal management solutions are simulated for a representative foldable smartphone with screen dimensions of 144 × 138.3 mm2 (twice the screen of iPhone 6 s with a 10 mm gap). In addition, the simulation includes two heat sources representing a main processor with dimensions of 14.45 × 14.41 mm2 and power of 3.3 W (A9 processor in iPhone 6S) and a broadband processor with dimensions of 8.26 × 9.02 mm2 and power of 2.5 W (Qualcomm broadband processor). For the simulation, a finite element method (FEM) model is calibrated and verified by steady-state experiments of two different TGPs. The calibrated model is then used to study three different cases: a graphite heat spreader, two TGPs with a graphite hinge, and a single, large, and foldable TGP. In the fully unfolded configuration, using a graphite heat spreader, the temperature difference across the spreader's surface is about 17 °C. For the design using two TGPs connected by a graphite bridge, the temperature difference is about 7.2 °C. Finally, for the design using a single large TGP with a joint region, the temperature difference is only 1–2 °C. These results suggest that a single foldable TGP or a configuration with two TGPs outperform the graphite sheet solution for the thermal management of foldable smartphones.

Thermal Performance of Natural Graphite Heat Spreaders

2005 ◽  
Author(s):  
Martin Smalc ◽  
Gary Shives ◽  
Gary Chen ◽  
Shrishail Guggari ◽  
Julian Norley ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Management ◽  
Numerical Models ◽  
Laptop Computer ◽  
Natural Graphite ◽  
Heat Spreader ◽  
Graphite Sheet ◽  
Cooling Fan ◽  
Heat Spreaders ◽  
Graphite Heat

Heat spreaders can be made from natural graphite sheet materials. These spreaders take advantage of the anisotropic thermal properties of natural graphite. Natural graphite exhibits a high thermal conductivity in the plane of the sheet combined with a much lower thermal conductivity through the thickness of the sheet. As a result, a natural graphite sheet can function as both a heat spreader and an insulator and can be used to eliminate localized hot spots in electronic components. In some cases, a natural graphite heat spreader can replace a conventional thermal management system consisting of a heat sink and cooling fan. This paper examines the properties of natural graphite heat spreaders and the application of these spreaders to thermal management problems in laptop computers. The thermal and mechanical properties of natural graphite heat spreaders are presented along with a discussion of how those properties are measured. The use of a natural graphite heat spreader to reduce the touch temperature in a laptop computer is presented. Both experimental techniques and numerical models are used to examine performance of the heat spreader in this application.

A Comprehensive Review on Reconfigurable Drones: Classification, Characteristics, Design and Control Technologies

2021 ◽  
pp. 1-27
Author(s):  
Saddam Hocine Derrouaoui ◽  
Yasser Bouzid ◽  
Mohamed Guiatni ◽  
Islam Dib
Keyword(s):  
Fault Tolerant ◽  
Control Strategies ◽  
Cluttered Environments ◽  
Viable Solution ◽  
Promising Solution ◽  
Design Characteristics ◽  
And Performance ◽  
Control Technologies ◽  
And Control ◽  
Near Future

Recently, reconfigurable drones have gained particular attention in the field of automation and flying robots. Unlike the conventional drones, they are characterized by a variable mechanical structure in flight, geometric adaptability, aerial reconfiguration, high number of actuators and control inputs, and variable mathematical model. In addition, they are exploited to flight in more cluttered environments, avoid collisions with obstacles, transport and grab objects, cross narrow and small spaces, decrease different aerial damages, optimize the consumed energy, and improve agility and maneuverability in flight. Moreover, these new drones are considered as a viable solution to provide them with specific and additional functionalities. They are a promising solution in the near future, since they allow increasing considerably the capabilities and performance of classical drones in terms of multi-functionalities, geometric adaptation, design characteristics, consumed energy, control, maneuverability, agility, efficiency, obstacles avoidance, and fault tolerant control. This paper explores very interesting and recent research works, which include the classification, the main characteristics, the various applications, and the existing designs of this particular class of drones. Besides, an in-depth review of the applied control strategies will be presented. The links of the videos displaying the results of these researches will be also shown. A comparative study between the different types of flying vehicles will be established. Finally, several new challenges and future directions for reconfigurable drones will be discussed.

scholarly journals The Bearing Stiffness Effect on In-Wheel Motors

2020 ◽  
Vol 12 (10) ◽  
pp. 4070
Author(s):  
Matej Biček ◽  
Raphaël Connes ◽  
Senad Omerović ◽  
Aydin Gündüz ◽  
Robert Kunc ◽  
...  
Keyword(s):  
Thermal Management ◽  
Electric Vehicles ◽  
Automotive Industry ◽  
Motor Performance ◽  
Mechanical Design ◽  
Critical Component ◽  
Wide Range ◽  
Bearing Stiffness ◽  
Promising Solution ◽  
Electromagnetic Performance

In-wheel motors offer a promising solution for novel drivetrain architectures of future electric vehicles that could penetrate into the automotive industry by transferring the drive directly inside the wheels. The available literature mainly deals with the optimization of electromagnetically active parts; however, the mechanical design of electromagnetically passive parts that indirectly influence motor performance also require detailed analysis and extensive validation. To meet the optimal performance of an in-wheel motor, the mechanical design requires optimization of housing elements, thermal management, mechanical tolerancing and hub bearing selection. All of the mentioned factors have an indirect influence on the electromagnetic performance of the IWM and sustainability; therefore, the following paper identifies the hub bearing as a critical component for the in-wheel motor application. Acting loads are reviewed and their effect on component deformation is studied via analytically and numerically determined stiffness as well as later validated by measurements on the component and assembly level to ensure deformation envelope and functionality within a wide range of operations.

Thermodynamic peculiarities of alpha-type Stirling engines for low-temperature difference power generation: Optimisation of operating parameters and heat exchangers using a third-order model

2013 ◽  
Vol 228 (11) ◽  
pp. 1936-1947 ◽  
Author(s):  
Benedikt Hoegel ◽  
Dirk Pons ◽  
Michael Gschwendtner ◽  
Alan Tucker ◽  
Mathieu Sellier
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Operating Parameters ◽  
Heat Sources ◽  
Third Order ◽  
Concentrated Solar Energy ◽  
Stirling Engines ◽  
Temperature Heat

Low-temperature heat sources such as waste heat and geothermal energy in the range from 100 ℃ to 200 ℃ are widely available and their potential is largely untapped. Stirling engines are one possibility to convert this heat to a usable power output. Much work has been done to optimise Stirling engines for high-temperature heat sources such as external combustion or concentrated solar energy but only little is known about suitable engine layouts at lower temperature differences. With the reduced temperature difference, changes become necessary not only in the heat exchangers and the regenerator but also in the operating parameters such as frequency and phase angle. This paper shows results obtained from a third-order simulation model that help to identify beneficial parameter combinations, and explains the differences of low and high-temperature engines.

Fundamental Study on Thermal Characteristics of Heat Spreaders

2011 ◽  
Author(s):  
Yasushi Koito ◽  
Yusaku Nonaka ◽  
Toshio Tomimura
Keyword(s):  
Thermal Management ◽  
Theoretical Study ◽  
Thermal Characteristics ◽  
Thermal Design ◽  
Design Parameters ◽  
Heat Spreader ◽  
Fundamental Study ◽  
Discharge Characteristics ◽  
Heat Spreaders ◽  
Large Heat

A heat spreader is one of the solutions for thermal management of electronic and photonic systems. By placing the heat spreader between a small heat source and a large heat sink, the heat flux is spread from the former to the latter, resulting in a lower thermal spreading resistance between them. There are many types of heat spreaders known today having different heat transfer modes, shapes and sizes. This paper describes the theoretical study to present the fundamental data for the rational use and thermal design of heat spreaders. Two-dimensional disk-shaped mathematical model of the heat spreader is constructed, and the dimensionless numerical analysis is performed to investigate the thermal spreading characteristics of the heat spreaders. From the numerical results, the temperature distribution and the heat flow inside the heat spreaders are visualized, and then the effects of design parameters are clarified. The discussion is also made on the discharge characteristics of the heat spreaders. Moreover, a simple equation is proposed to evaluate the heat spreaders.

Research on Temperature Difference Controlling of Hot Rolling H-Beam

2014 ◽  
Vol 898 ◽  
pp. 221-224
Author(s):  
Jin Hong Ma ◽  
Bin Tao ◽  
Xiao Han Yao
Keyword(s):  
Temperature Difference ◽  
Equivalent Stress ◽  
Cooling Water ◽  
Rolling Process ◽  
Element Analysis ◽  
Fem Model ◽  
Product Size ◽  
H Beam ◽  
Section Result ◽  
Stress And Strain Distribution

Complex shape of H-beam section and uneven elimination of heat on the section result in too big temperature difference between web and flange. At the same time,as the roller cooling water forms tank on H-beam web, the section temperature difference further increases. Based on finite element analysis software DEFORM-3D, the FEM model of finished product size of H194×150×6×9 is established. Thermo-mechanical coupled method is adopted to simulate the rolling process of H-beam. The cooling water influence on section temperature distribution, equivalent stress and strain distribution is analyzed. The section temperature change characteristic are studied to provide reference for further research.

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