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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: In this paper, the influence of orientation on the steady laminar free convection heat transfer from a heated triangular cylinder (flat side facing downward and upward) in quiescent power-law fluids has been investigated.
Abstract: In this work, the influence of orientation on the steady laminar free convection heat transfer from a heated triangular cylinder (flat side facing downward and upward) in quiescent power-law fluids has been investigated. In particular, the coupled momentum and energy equations have been solved numerically over wide ranges of the relevant dimensionless parameters as: Grashof number (10 ≤ Gr ≤ 105), Prandtl number (0.72 ≤ Pr ≤ 100), and power-law index (0.3 ≤ n ≤ 1.8). The detailed flow and temperature fields in the vicinity of the heated cylinder are visualized in terms of the streamline and isotherm contours, respectively. At the next level, the influence of each of the governing parameters, namely, Grashof number (Gr), Prandtl number (Pr), and power-law index (n) on the local and average Nusselt number and drag coefficient, is examined. The flow separation was found to occur at high Grashof numbers and low Prandtl numbers, but only in shear-thickening and Newtonian fluids (n ≥ 1) for the cylinder orienta...
15 citations
16 Apr 2007
TL;DR: In this article, a CFD-aided profile prediction algorithm was developed and applied to modelling of preheating of a PCB with non-uniform distribution of component thermal mass in a forced air convection solder reflow oven.
Abstract: A CFD-aided reflow oven profile prediction algorithm has been developed and applied to modelling of preheating of a PCB with non-uniform distribution of component thermal mass in a forced air convection solder reflow oven. The iterative algorithm combines an analytic approach with CFD modelling. It requires an experimentally validated CFD model of the solder reflow oven and a CFD model of the PCB as main inputs. Results of computational experiments have been presented to reveal good agreement between predicted PCB profiles and corresponding CFD calculations. Application guidelines contained in the description of the algorithm will assist potential users both during the virtual prototyping phase of a PCB including designing for assembly and in the phase of reflow oven profiling.
15 citations
01 Jan 1993
TL;DR: In this article, an experimental apparatus was designed, built and used to study the behavior of transient forced convection in a rectangular duct with and without barriers due to a sinusoidal heat input at the inlet, to simulate the electric heating and cooling inside the computer.
Abstract: An experimental apparatus was designed, built and used to study the behavior of transient forced convection in a rectangular duct with and without barriers due to a sinusoidal heat input at the inlet, to simulate the electric heating and cooling inside the computer. A wide range of Reynolds number (400 ≤Re ≤ 20,000) and inlet frequencies (0.01 Hz ≤ β ≤ 0.08 Hz) was covered in this experimental study for both laminar and turbulent flow. The experiments are carried out in the thermal entrance region with the fully developed velocity profile. The temperature variation at several locations along the duct was measured and recorded, and the experiment results showed that the oscillation at different locations are the sine variation with the same period as the heat input, while its amplitude decayed exponentially along the duct. The decay indexes are obtained from the experimental investigation under different conditions and presented in tabular and graphical forms.
15 citations
TL;DR: In this paper, a combined power and cooling (CPC) system is established between high temperature incoming air and low temperature fuel based on fuel cooling air turbine and organic Rankine cycle (ORC).
15 citations
TL;DR: In this paper, a case study of circuit cards consisting of dense circuitry is discussed, where the authors use physics of failure (PoF) analysis to understand the cause and effect of physical processes and mechanisms that cause degradation and failure of materials and components.
Abstract: Published studies and audits have documented that a significant number of U.S. Army systems are failing to demonstrate established reliability requirements. In order to address this issue, the Army developed a new reliability policy in December 2007 which encourages use of cost-effective reliability best practices. The intent of this policy is to improve reliability of Army systems and material, which in turn will have a significant positive impact on mission effectiveness, logistics effectiveness and life-cycle costs. Under this policy, the Army strongly encourages the use of Physics of Failure (PoF) analysis on mechanical and electronics systems. At the US Army Materiel Systems Analysis Activity, PoF analyses are conducted to support contractors, program managers and engineers on systems in all stages of acquisition from design, to test and evaluation (T&E) and fielded systems. This article discusses using the PoF approach to improve reliability of military products. PoF is a science-based approach to reliability that uses modeling and simulation to eliminate failures early in the design process by addressing root-cause failure mechanisms in a computer-aided engineering environment. The PoF approach involves modeling the root causes of failure such as fatigue, fracture, wear, and corrosion. Computer-aided design tools have been developed to address various loads, stresses, failure mechanisms, and failure sites. This paper focuses on understanding the cause and effect of physical processes and mechanisms that cause degradation and failure of materials and components. A reliability assessment case study of circuit cards consisting of dense circuitry is discussed. System level dynamics models, component finite element models and fatigue-life models were used to reveal the underlying physics of the hardware in its mission environment. Outputs of these analyses included forces acting on the system, displacements of components, accelerations, stress levels, weak points in the design and probable component life. This information may be used during the design process to make design changes early in the acquisition process when changes are easier to make and are much more cost effective. Design decisions and corrective actions made early in the acquisition phase leads to improved efficiency and effectiveness of the T&E process. The intent is to make fixes prior to T&E which will reduce test time and cost, allow more information to be obtained from test and improve test focus. PoF analyses may be conducted for failures occurring during test to better understand the underlying physics of the problem and identify the root cause of failures which may lead to better fixes for problems discovered, reduced test-fix-test iterations and reduced decision risk. The same analyses and benefits mentioned above may be applied to systems which are exhibiting failures in the field.
14 citations
Cites methods from "Cooling techniques for electronic e..."
...The out-of-plane fatigue life estimate is based on Steinberg’s fatigue model [8]....
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