Book•
Cooling techniques for electronic equipment
07 Nov 1980-
TL;DR: In this article, the authors present practical guides for Natural Convection and Radiation Cooling for Electronic Components. But they do not consider the effects of thermal stresses in lead wires, Solder Joints and Plated Throughholes.
Abstract: Evaluating the Cooling Requirements. Designing the Electronic Chassis. Conduction Cooling for Chassis and Circuit Boards. Mounting and Cooling Techniques for Electronic Components. Practical Guides for Natural Convection and Radiation Cooling. Forced--Air Cooling for Electronics. Thermal Stresses in Lead Wires, Solder Joints, and Plated Throughholes. Predicting the Fatigue Life in Thermal Cycling and Vibration Environment. Transient Cooling for Electronic Systems. Special Applications for Tough Cooling Jobs. Effective Cooling for Large Racks and Cabinets. Finite Element Methods for Mathematical Modeling. Environmental Stress Screening Techniques. References. Index.
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TL;DR: The Prandtl number is found to have a significant impact on the thermal characteristics of the recirculating wake, and the local minimum heat transfer rate along the cylinder surface is found at the position where the swells of the isotherms form.
Abstract: The effect of the Prandtl number (Pr) on the flow and heat transfer from a porous circular cylinder with internal heat generation in the mixed convection regime is numerically investigated. The steady flow regime is considered over the ranges of the Reynolds number (Re), Darcy number (Da), and Richardson number (Ri), varying from 5 to 40, 10-6 to 10-2, and 0 to 2, respectively. The wake structure, the temperature distribution, and the heat transfer rate are discussed. Besides precipitating the growth of the recirculating wake, the Prandtl number is found to have a significant impact on the thermal characteristics. The concave isotherms, resembling a saddle-shaped structure, occur behind the cylinder at larger Pr, resulting in swells of the isotherms pairing off at the lateral sides. These swells are found to have a negative effect on heat transfer owing to a relatively smaller temperature gradient there. Then, the heat transfer rate in terms of the local Nusselt number (Nu) and enhancement ratio (Er) is calculated, which is closely related to Pr, Re, Da, and Ri. The local minimum heat transfer rate along the cylinder surface is found at the position where the swells of the isotherms form.
5 citations
Proceedings Article•
01 Mar 2019
TL;DR: In this paper, the thermal and electromagnetic effects of varying the ground plane thickness and aperture size of the 5G integrated base station antennas are investigated using a double-sided PCB structure with antennas and digital beamforming chips on the opposite sides.
Abstract: The thermal and electromagnetic effects of varying the ground plane thickness and aperture size of the 5G integrated base station antennas are investigated. A double-sided PCB structure is designed with antennas and digital beamforming chips on the opposite sides. Fully-passive cooling is achieved by using fanless CPU coolers attached to the chips. The simulation results indicate that as compared to the standard counterparts, much better cooling performance can be achieved using relatively thick ground planes with extended aperture sizes, with no significant effect on the electromagnetic properties.
5 citations
29 May 1996
TL;DR: In this article, the authors present a solution methodology for the optimal placement of convectively and conductively air-cooled electronic components on planar printed wiring boards considering thermal and electrical/cost design objectives.
Abstract: This paper presents a solution methodology for the optimal placement of convectively and conductively air-cooled electronic components on planar printed wiring boards considering thermal and electrical/cost design objectives. The methodology combines the use of a heat transfer solver for the prediction of the temperature distribution among the electronic components and a genetic algorithm for the adaptive search of optimal or near optimal solutions and a multiobjective optimization strategy (Pareto optimization and Multiattribute utility analysis). After proper validation of the elements of the solution methodology (heat transfer solver/genetic algorithm) in isolation, the methodology under consideration is tested using a placement problem (case study) that considers as optimization criteria the minimization of an estimate of the failure rate of the system of components due to thermal overheating (via an Arrhenius relation) and the minimization of the total wiring length (given some interconnectivity requirements). Results corresponding to the case study are presented and discussed for both Pareto optimization and Multiattribute utility analysis.
5 citations
19 May 1992
TL;DR: In this paper, a method of predicting the impact of thermal gradients in a power IC on circuit operation and performance is proposed combining ANSYS 3-dimensional finite element analysis (FEA) with non-isothermal HSPICE circuit simulation.
Abstract: PROPOSED METHODOLOGY A novel method of predicting the impact of thermal gradients in a power IC on circuit operation and performance is proposed combining ANSYS 3-dimensional finite element analysis (FEA) with non-isothermal HSPICE circuit simulation. The influence of a dominant heat source in a power IC on other non-power devices used in analog and digital control circuitry is studied. Heat redistribution by on-chip aluminum interconnects and contact openings is aIso explored. Using a full 3D ANSYS simulation of a power IC, predicted isotherms are correlated to thermally induced differential pair offset voltage predicted by non-isothermal HSPICE simulation. Finally, an electrothermal circuit analysis methodology is proposed along with a discussion of practical and computational limitations.
5 citations
TL;DR: In this article, the authors investigated the convective heat transfer in a cavity with ventilation ports and found that for a given aspect ratio with an increase in Re, the heat source Nu increases.
Abstract: Our objective in this study was to investigate the convective heat transfer in a cavity with ventilation ports. The study has been divided into experimental and numerical sections and under the experimental study the enclosure considered with two exit ports at roof and one inlet opening with varying aspect ratio. Under the numerical study, the model validation is done at AR = 5, and then the study continued for one exit port each on the left side and right side. The enclosure is equipped with three discrete heat sources at the bottom wall and with an exhaust fan at the exit port. The ranges of parameters considered under experimental study as 1.25 ≤ AR ≤ 2.5, 3224 ≤ Re ≤ 6579, 8.5 × 106 ≤ Gr ≤ 1.03 × 108, and as a consequence Richardson number obtained in the range 0.21–9.58. Experimental results set out that the heat source surface Nusselt number decreases with an increase in aspect ratio however; at higher aspect ratio, the values of Nusselt number remain almost unchanged. The enclosure bulk fluid Nusselt number increases with an increase in aspect ratio. The study revealed that for a given aspect ratio with an increase in Re, the heat source Nu increases. The numerical study divulged that the ventilation port arrangement at the right side of enclosure exhibits the better thermal performance among all the three orientations considered and the results are supported with the streamline and temperature contours. The study of varying inlet port height disclosed that as the inlet port height is increased, the heater surface temperature drops and the enhanced heat transfer is achieved.
5 citations