Thermal Enhancement Coatings for Microelectronic Systems

1998 ◽  
Vol 120 (3) ◽  
pp. 229-237 ◽  
Author(s):  
L. S. Fletcher ◽  
M. A. Lambert ◽  
E. E. Marotta
Keyword(s):  
Heat Generation ◽  
Thermal Performance ◽  
Electronic Components ◽  
Thermally Induced ◽  
Thermal Enhancement ◽  
Thermally Conducting ◽  
Power Densities

The power densities and heat generation in microelectronic systems have increased dramatically as individual electronic components have been miniaturized. As a result of the growing number of thermally-induced failures in these systems, their thermal performance has become the focus of increasing concern. The use of thermally conducting interstitial coatings within and between electronic components has proven to be one technique suitable for thermal enhancement. This review will address both metallic and nonmetallic coatings suitable for thermal enhancement and discuss some of the major areas of application.

Robust Design Techniques for Evaluating Fuel Cell Thermal Performance

2006 ◽  
Author(s):  
Kenneth J. Kelly ◽  
Gregory C. Pacifico ◽  
Michael Penev ◽  
Andreas Vlahinos
Keyword(s):  
Fuel Cell ◽  
Heat Generation ◽  
Thermal Performance ◽  
Gas Flow ◽  
Internal Heat ◽  
Flow Path ◽  
Coolant Flow ◽  
Design Parameters ◽  
Fuel Cell Stack ◽  
Path Design

The National Renewable Energy Laboratory (NREL) and Plug Power Inc. have been working together to develop fuel cell modeling processes to rapidly assess critical design parameters and evaluate the effects of variation on performance. This paper describes a methodology for investigating key design parameters affecting the thermal performance of a high temperature, polybenzimidazole (PBI)-based fuel cell stack. Nonuniform temperature distributions within the fuel cell stack may cause degraded performance, induce thermo-mechanical stresses, and be a source of reduced stack durability. The three-dimensional (3-D) model developed for this project includes coupled thermal/flow finite element analysis (FEA) of a multi-cell stack integrated with an electrochemical model to determine internal heat generation rates. Sensitivity and optimization algorithms were used to examine the design and derive the best choice of the design parameters. Initial results showed how classic design-of-experiment (DOE) techniques integrated with the model were used to define a response surface and perform sensitivity studies on heat generation rates, fluid flow, bipolar plate channel geometry, fluid properties, and plate thermal material properties. Probabilistic design methods were used to assess the robustness of the design in response to variations in load conditions. The thermal model was also used to develop an alternative coolant flow-path design that yields improved thermal performance. Results from this analysis were recently incorporated into the latest Plug Power coolant flow-path design. This paper presents an evaluation of the effect of variation on key design parameters such as coolant and gas flow rates and addresses uncertainty in material thermal properties.

Performance Enhancement of Air Cooled Heat Sink Used in Inverter Drives of Residential Air Conditioners

2020 ◽  
Vol 28 (01) ◽  
pp. 2050008
Author(s):  
Vignesh Lakshmanan ◽  
Pushpak Doiphode ◽  
Indraneel Samanta
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Sink ◽  
Performance Enhancement ◽  
Air Conditioner ◽  
Electronic Components ◽  
Variable Frequency Drive ◽  
Air Conditioners ◽  
Baseline Case ◽  
Heating Load

Inverter air conditioners are being widely used in the air conditioning sector for energy saving purposes. These air conditioners use an inverter or a variable frequency drive (VFD) to control the compressor operating speed based on cooling or heating load fluctuations. If the heat generated by the electronic components of the VFD is not dissipated properly, it can lead to failure of the VFD. In general, a heat sink is used for dissipating the heat generated by the electronic components of the VFD. The heat sink can be either air cooled or liquid cooled. Using computational fluid dynamics (CFD), this paper deals with optimization of the thermal performance of an air cooled plate-fin heat sink with rectangular fins used in a residential split inverter air conditioner. Commercially available CFD tool has been used for simulations. It has been observed that enhancing fluid flow around the heat sink and improving heat transfer area of the fins significantly improve the thermal performance of the heat sink. By using heat sink with rectangular fins having a stepped profile, it has been possible to improve the heat transfer from the baseline case by 27%. Whereas, by using hollow fins, heat transfer improvement of 20% has been achieved.

scholarly journals Experimental Study on Thermal Performance of a Bent Copper-Water Heat Pipe

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shuangshuang Miao ◽  
Jiajia Sui ◽  
Yulong Zhang ◽  
Feng Yao ◽  
Xiangdong Liu
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Critical Heat Flux ◽  
Working Conditions ◽  
Thermal Performance ◽  
Heat Input ◽  
High Heat ◽  
High Heat Flux ◽  
Electronic Components ◽  
Copper Water

Vapor-liquid phase change is regarded as an efficient cooling method for high-heat-flux electronic components. The copper-water bent heat pipes are particularly suited to the circumstances of confined space or misplaced heat and cold sources for high-heat-flux electronic components. In this paper, the steady and transient thermal performance of a bent copper-water heat pipe is studied based on a performance test system. The effects of cooling temperature, working conditions on the critical heat flux, and equivalent thermal conductivity have been examined and analyzed. Moreover, the influences of heat input and working conditions on the thermal response of a bent heat pipe have also been discussed. The results indicate that the critical heat flux is enhanced due to the increases in cooling temperature and the lengths of the evaporator and condenser. In addition, the critical heat flux is improved by extending the cooling length only when the operating temperature is higher than 50°C. The improvement on the equivalent thermal by increasing the heating length is more evident than that by increasing cooling length. It is also demonstrated by the experiment that the bent copper-water heat pipe can respond quickly to the variation of heat input and possesses superior transient heat transfer performance.

Uneven heat generation and thermal performance of spindle bearings

2018 ◽  
Vol 126 ◽  
pp. 324-335 ◽  
Author(s):  
Yanfei Zhang ◽  
Xiao hu Li ◽  
Jun Hong ◽  
Ke Yan ◽  
Sen Li
Keyword(s):  
Heat Generation ◽  
Thermal Performance

Experimental Characterization of a Carbon Fiber Composite Material Heat Sink in Boiling Heat Transfer Using FC-72

2006 ◽  
Author(s):  
Venugopal Gandikota ◽  
Harish Chengalvala ◽  
Amy S. Fleischer ◽  
G. F. Jones
Keyword(s):  
Heat Transfer ◽  
Composite Material ◽  
Carbon Fiber ◽  
Thermal Management ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Fluxes ◽  
Two Phase ◽  
Operating Temperatures ◽  
Power Densities

The on-going trend towards increasing device performance while shrinking device size often results in escalating power densities and high operating temperatures. High operating temperatures may lead to reduced reliability and induced thermal stresses. Therefore, it is necessary to employ new and innovative thermal management techniques to maintain a suitable junction temperature at high power densities. For this reason, there is interest in a variety of liquid cooling techniques. This study analyzes a composite material heat sink. The heat sink consists of a very large number of small cross-section fins fabricated from carbon pitch fibers and epoxy. These carbon pitch fibers have a high thermal conductivity along the length of the fin. It is expected that the longer length will result in more heat transfer surface area and a more effective heat sink. This experimental study characterizes the thermal performance of the carbon-fiber heat sink in a two-phase closed loop thermosyphon using FC-72 as the operating fluid. The influence of heat load, thermosyphon fill volume, and condenser operating temperature on the overall thermal performance is examined. The results of this experiment provide significant insight into the possible implementation and benefits of carbon fiber heat sink technology in two-phase flow leading to significant improvements in thermal management strategies for advanced electronics. The carbon fiber heat sink yielded heat transfer coefficients in the range of 1300-1500 W/m2 K for heat fluxes in the range up to 3.2 W/cm2. Resistances in the range of 0.20 K/W – 0.23 K/W were achieved for the same heat fluxes. Condenser temperature and fill ratio did not show a significant effect on any of the results.

Analytical study of thermal variation impact on dynamics of a spindle bearing system

2019 ◽  
Vol 233 (4) ◽  
pp. 871-898 ◽  
Author(s):  
Mohammed Alfares ◽  
Omar Saleem ◽  
Majed Majeed
Keyword(s):  
Differential Equations ◽  
Thermal Effect ◽  
Heat Generation ◽  
Thermal Model ◽  
Nonlinear Dynamical System ◽  
Rotating Shaft ◽  
Thermally Induced ◽  
Spindle Bearing ◽  
The Impact ◽  
Bearing System

Changes in the thermal status of machine tools spindle-bearing system can have a noticeable effect on the performance of the machine itself, and therefore studying the thermal effect on the performance ball bearing during service is important. For this purpose, a study was carried out where a simple rotating shaft system supported by two angular contact ball bearings was taken into consideration. Heat was generated due to the contact between the balls and rings of the bearing. This thermal effect on the dynamics of the system was studied using a transient thermal model. The system was divided into nodes; each was assumed to be a uniform temperature. Thermal energy balance was used on each node to obtain a set of differential equations. ODE solver in MATLAB was used to solve the resulting system of differential equations. The thermal model considered an initial preload as well as the thermal preload that is caused by the uneven expansion of bearing components. In this research, a 5 DOF nonlinear dynamical system model is integrated with a spindle-bearing thermal model and then utilized to study the impact of preload variations on the spindle-bearing system of a grinding machine. The effect of different system parameters such as speed of rotation, type of bearing, ambient temperature, type of oil, initial preload on temperature output and thermal growth within the system was studied. The study shows that the heat generation rate is directly proportional to the rotational speed of the shaft and higher thermally induced preload is reached at higher speeds. It is also noticed that initial preload has a small effect on the heat generation, thermally induced preload, and temperature of the bearing. Also, the dominant frequency values of the spindle system generally increase with changing thermally induced preload values. This study is useful in predicting the thermal profile as well as preload value resulting in the bearing assembly, which in turn will be used to predict variation in the dynamics of the system.

Thermal Performance Analysis for High-Speed Spindle of Horizontal Machining Center

2011 ◽  
Vol 179-180 ◽  
pp. 298-303
Author(s):  
Zhi Feng Liu ◽  
Zhong Hua Chu ◽  
Qiang Cheng ◽  
Guang Bo Liu
Keyword(s):  
Heat Generation ◽  
Thermal Performance ◽  
High Speed ◽  
Three Dimensional ◽  
Stable Condition ◽  
Machining Process ◽  
Analysis Model ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
Radiation Mechanism

In order to show the thermal performance of spindle by rule and line, firstly, this paper presents a three-dimensional finite element analysis model for thermal analysis of high speed spindle; Then by studying the heat generation and radiation mechanism of the spindle, temperature distribution has been analyzed accurately and intuitively under the heat-stable condition based on the three-dimensional model; Finally effective actions have been proposed to improve the condition of the spindle's heat generation, and thus can guarantee the highly effective characteristic of the spindle in machining process.

Effects of Servers' Rack Location and Power Loading Configurations on the Thermal Management of Data Center Racks' Array

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
S. A. Nada ◽  
K. E. Elfeky
Keyword(s):  
Energy Efficiency ◽  
Thermal Management ◽  
Thermal Performance ◽  
Data Center ◽  
Real Data ◽  
Heat Index ◽  
Power Loading ◽  
And Performance ◽  
High Level ◽  
Power Densities

Effects of server/rack locations and server loading configurations on the thermal performance of data center racks' array are experimentally investigated using a scaled physical model simulating real data. Front and rear rack temperatures profiles, server temperatures, and performance indices supply/return heat index (SHI/RHI) are used to evaluate the thermal management of the racks' array. The results showed that (i) servers located in high level rack cabinet have the worst thermal performance, (ii) middle racks of the rack row showed optimum thermal performance and energy efficiency, and (iii) locating the servers of high power densities in the middle of the racks row improves the thermal performance and energy efficiency of the racks array.

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