Three-Dimensional Simulation of Thermoelectric Devices With Compact Numerical Models

2003 ◽  
Author(s):  
Eric Prather ◽  
Bhalchandra Puranik
Keyword(s):  
Heat Source ◽  
Heat Sink ◽  
Numerical Models ◽  
Three Dimensional ◽  
Electronics Cooling ◽  
Step Function ◽  
Compact Model ◽  
Zone Model ◽  
Detailed Model ◽  
Source Power

Thermoelectric cooling modules (TECs) are widely used within electronic equipment for both temperature reduction and control of individual components. The techniques presented in this paper demonstrate that it is possible to construct a simple three-zone model, that represents the transient and 3D properties of a typical TEC, and can be easily built within existing CFD software packages for a known electric current or voltage input. A comparison of compact model results, detailed model results, and experimental results is presented for a typical electronics cooling setup, including a heat source (from which heat is absorbed by the TEC), TEC device, and air-cooled heat sink. Variables examined include heat source power dissipation, TEC current, and heat sink airflow. Finally, the response of the setup to a step function in current is examined to investigate the transient performance of the compact model.

Transient Analysis of Nonuniform Heat Input Propagation Through a Heat Sink Base

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Srivathsan Sudhakar ◽  
Justin A. Weibel
Keyword(s):  
Heat Source ◽  
Heat Input ◽  
Heat Sink ◽  
Three Dimensional ◽  
Temperature Response ◽  
Flow Distribution ◽  
Temporal Variations ◽  
Step Response ◽  
Dimensional System ◽  
Two Phase

For thermal management architectures wherein the heat sink is embedded close to a dynamic heat source, nonuniformities may propagate through the heat sink base to the coolant. Available transient models predict the effective heat spreading resistance to calculate chip temperature rise, or simplify to a representative axisymmetric geometry. The coolant-side temperature response is seldom considered, despite the potential influence on flow distribution and stability in two-phase microchannel heat sinks. This study solves three-dimensional transient heat conduction in a Cartesian chip-on-substrate geometry to predict spatial and temporal variations of temperature on the coolant side. The solution for the unit step response of the three-dimensional system is extended to any arbitrary temporal heat input using Duhamel's method. For time-periodic heat inputs, the steady-periodic solution is calculated using the method of complex temperature. As an example case, the solution of the coolant-side temperature response in the presence of different transient heat inputs from multiple heat sources is demonstrated. To represent a case where the thermal spreading from a heat source is localized, the problem is simplified to a single heat source at the center of the domain. Metrics are developed to quantify the degree of spatial and temporal nonuniformity in the coolant-side temperature profiles. These nonuniformities are mapped as a function of nondimensional geometric parameters and boundary conditions. Several case studies are presented to demonstrate the utility of such maps.

Mixed Convection of Impinging Air Cooling Over Heat Sink in Telecom System Application

2004 ◽  
Vol 126 (4) ◽  
pp. 519-523 ◽  
Author(s):  
Siddharth Bhopte ◽  
Musa S. Alshuqairi ◽  
Dereje Agonafer ◽  
Gamal Refai-Ahmed
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Mixed Convection ◽  
Heat Sink ◽  
Three Dimensional ◽  
Source Surface ◽  
Air Cooling ◽  
Transfer Rates ◽  
Nusselt Numbers ◽  
Air Jet

The current numerical investigation will examine the effect of an impinging mixed convection air jet on the heat transfer rate of a parallel flat plate heat sink. A three-dimensional numerical model was developed to evaluate the effects of the nozzle diameter d, nozzle-to-target vertical placement H/d, Rayleigh number, and the jet Reynolds number on the heat transfer rates from a discrete heat source. Simulations were performed for a Prandtl number of 0.7 and for Reynolds numbers ranging from 100 to 5000. The governing equations were solved in the dimensionless form using a commercial finite-volume package. Average Nusselt numbers were obtained, at H/d=3 and two jet diameters, for the bare heat source, for the heat source with a base heat sink, and for the heat source with the finned heat sink. The heat transfer rates from the bare heat source surface have been compared with the ones obtained with the heat sink in order to determine the overall performance of the heat sink in an impingement configuration.

scholarly journals Experimental and simulation of C45 steel bar heat treatment with the GTAW method application

2020 ◽  
Author(s):  
Adam Kulawik ◽  
Joanna Wróbel ◽  
Michał Sobiepański
Keyword(s):  
Heat Treatment ◽  
Heat Source ◽  
Dimensional Space ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Medium Carbon Steel ◽  
Efficiency Coefficient ◽  
Source Power ◽  
Gas Tungsten Arc ◽  
Steel Bar

Abstract The motivation of the paper is an attempt to indicate the relationship between the selected Gas Tungsten Arc Welding (GTAW) technology and the parameters of the boundary conditions for the simulation of the heat treatment process of elements made of medium-carbon steel. The authors of the paper prepared and described a series of numerical simulations and experimental studies concerning this problem. Simulations often use previously-developed analytical equations to describe the relationships between process parameters. The results obtained for the input data for determining the heat source power (voltage) from the analytical equation and experimental measurements were compared. Several cases of the size of the areas of direct influence of the GTAW arc (various radius of a simulation heat source) were analysed. All computations were performed in the author’s software based on Finite Element Method (FEM) solving the heat transfer equation with the convection term. In this paper, the GTAW heating parameters (boundary condition) for a current intensity equal 30 A were identified. With the assumed arc efficiency coefficient, the arc voltage set on the device and the measured value of the arc current, the optimum radius of the heat source was determined. The identification of parameters was confirmed by the convergence of the results of numerical simulation in three-dimensional space (3D) with the results of the experiment. Unfortunately, the applied methodology did not give good results for current equal to 50A.

Piezoelectric Fans: Heat Transfer Enhancements for Electronics Cooling

2008 ◽  
Author(s):  
James Petroski ◽  
Mehmet Arik ◽  
Mustafa Gursoy
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Heat Sink ◽  
Three Dimensional ◽  
Electronics Cooling ◽  
Coefficient Of Performance ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Piezoelectric Fans

Piezoelectric fans have been investigated for electronics cooling over the last decade. The primary usage or method has been to place the vibrating fan near the surface to be cooled. The piezofan used in the current study is composed of a piezo actuator attached to a flexible metal beam. It is operated at up to 120VAC and at 60 Hz. While most of the research in the literature focused on cooling bare surfaces, larger heat transfer rates are of interest in the present study. A proposed system of piezoelectric fans and heat sink is presented as a more efficient method of system cooling with these fans. In this paper, a heat sink and piezoelectric fan system demonstrated a capability of cooling an area of about 75 cm2 (about 1 C/W) where electronic assemblies can be mounted. The heat sink not only provides surface area, but also flow shaping for the unusual three-dimensional flow field of the fans. A volumetric coefficient of performance (COPv) is proposed, which allows a piezofan and heat sink system volume to be compared against the heat dissipating capacity of a similar heat sink of the same volume for natural convection. A piezofan system is shown to have a COPv of five times of a typical natural convection solution. The paper will further discuss the effect of nozzles in flow shaping obtained via experimental and computational studies. A three-dimensional flow field of the proposed cooling scheme with a piezofan is obtained via laser Doppler anemometry (LDA) flow visualization method. Velocities at the heat sink in the order of 1.5 m/s were achieved through this critical shaping. Finally, the overall system characterization to different heat loads and fan amplitudes will be discussed.

Design of Air-Cooled Heat Sink for a 55-kW Power Inverter With Laminar Flow

2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Rao V. Arimilli ◽  
Ali Hossein Nejad ◽  
Kivanc Ekici
Keyword(s):  
Laminar Flow ◽  
Heat Sink ◽  
Cell Model ◽  
Numerical Models ◽  
Three Dimensional ◽  
Transfer Model ◽  
Simplified Approach ◽  
Maximum Surface ◽  
Thermal Requirements ◽  
Surface Temperatures

A methodology is developed for the design of an air-cooled 55-kW-rated inverter heat sink. The design constraints are that the power density (PD) must meet or exceed the values associated with liquid-cooled systems of the same power rating, and that the maximum surface temperatures be less than 200 °C. To keep the pressure drop low relative to turbulent flow designs, a laminar flow regime is chosen. A preliminary design that satisfies the PD constraint exactly, and the thermal requirements approximately, is determined. To ensure that the thermal requirements are met by the design configuration, a thermal-fluid analysis based on a three-dimensional conjugate heat transfer model is conducted. Overall, energy balance errors (OEBEs) as high as 15% were encountered in the numerical models. These errors are reduced by taking advantage of the symmetry between fins using a typical unit cell model. A new simplified approach for the simulations was identified which involved modeling fins as highly conductive layers instead of solid domains. This further reduced the OEBEs to less than 0.004%. The design factors considered in this study include effective cooling surface area, fin thickness, fin spacing, and fin height. The results show that the maximum surface temperatures can be kept below 200 °C for safe operation of SiC devices in the inverter module while increasing the PD.

Mixed Convection of Impinging Air Cooling Over Heat Sink in Telecom System Application

2003 ◽  
Author(s):  
Musa S. Alshuqairi ◽  
Gamal Refai-Ahmed ◽  
Dereje Agonafer
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Mixed Convection ◽  
Heat Sink ◽  
Three Dimensional ◽  
Air Cooling ◽  
Transfer Rates ◽  
Nusselt Numbers ◽  
Air Jet ◽  
Discrete Heat Source

The current numerical investigation will examine the effect of an impinging mixed convection air jet on the heat transfer rate of a parallel flat plate heat sink. A three-dimensional numerical model was developed to evaluate the effects of the nozzle diameter (d), nozzle-to-target vertical placement (H/d), Rayleigh number and the jet Reynolds number on the heat transfer rates from a discrete heat source. Simulations were performed for a Prandtl number of 0.7 and for Reynolds numbers ranging from 100 to 5000. The governing equations were solved in the dimensionless form using a commercial finite-volume package. Average Nusselt numbers were obtained, at H/d = 3 and two jet diameters, for the bare heat source, for the heat source with a base heat sink and for the heat source with the finned heat sink. The heat transfer rates from the bare heat sources surface have been compared with the ones obtained with the heat sink in order to determine the overall performance of the heat sink in an impingement configuration.

scholarly journals Diffusion Model of Preemptive-Resume Priority Systems and Its Application to Performance Evaluation of SDN Switches

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5042
Author(s):  
Tomasz Nycz ◽  
Tadeusz Czachórski ◽  
Monika Nycz
Keyword(s):  
Diffusion Approximation ◽  
Numerical Models ◽  
Software Defined Networks ◽  
Detailed Model ◽  
Preemptive Resume ◽  
Central Controller ◽  
Priority Systems ◽  
Primary Element ◽  
Preemptive Resume Priority ◽  
General Distributions

The increasing use of Software-Defined Networks brings the need for their performance analysis and detailed analytical and numerical models of them. The primary element of such research is a model of a SDN switch. This model should take into account non-Poisson traffic and general distributions of service times. Because of frequent changes in SDN flows, it should also analyze transient states of the queues. The method of diffusion approximation can meet these requirements. We present here a diffusion approximation of priority queues and apply it to build a more detailed model of SDN switch where packets returned by the central controller have higher priority than other packets.

scholarly journals Effect of the Rock Stress on the Water Jet Cutting Performance

2021 ◽  
Author(s):  
Battista Grosso ◽  
Valentina Dentoni ◽  
Augusto Bortolussi
Keyword(s):  
Numerical Models ◽  
Step Function ◽  
Water Jet ◽  
The State ◽  
Cutting Performance ◽  
Lagrangian Analysis ◽  
State Of Stress ◽  
Water Jet Cutting ◽  
Cutting Rate ◽  
Available Technology

AbstractUnderground quarrying is rarely adopted for granite extraction due to the difficulties in the implementation of traditional technologies (drilling and explosive). As alternative to drilling and explosive, the combination of diamond wire and water jet seems to be the most promising available technology. The cutting performance achievable with the water jet technology depends on the operative parameters, the material characteristics and the state of stress within the rock massif. To assess the effect of the state of stress on the cutting rate, laboratory tests have been performed with an oscillating water jet machine on granite samples subjected to a static load. The stress distribution in the layer of rock to be removed has been evaluated by numerical simulation with the FLAC code (Fast Lagrangian Analysis of Continua). The correlation between the results of the cutting tests and the numerical models of the rock samples has been inferred. Starting from a conceptual model, which theoretically describes the relationship between the cutting rate and the stress, a step function was defined that indicates the ranges of stress where predefined values of the cutting rate are workable.

scholarly journals Experimental and Numerical Investigation of 3D Dam-Break Wave Propagation in an Enclosed Domain with Dry and Wet Bottom

2021 ◽  
Vol 11 (12) ◽  
pp. 5638
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Hasan Guzel ◽  
Kaan Dal ◽  
Ada Yilmaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Three Dimensional ◽  
Dam Break ◽  
Dam Failure ◽  
Navier Stokes ◽  
Negative Wave ◽  
Through Flow ◽  
Instantaneous Removal ◽  
Surface Patterns

Dam-break flood waves represent a severe threat to people and properties located in downstream regions. Although dam failure has been among the main subjects investigated in academia, little effort has been made toward investigating wave propagation under the influence of tailwater depth. This work presents three-dimensional (3D) numerical simulations of laboratory experiments of dam-breaks with tailwater performed at the Laboratory of Hydraulics of Iskenderun Technical University, Turkey. The dam-break wave was generated by the instantaneous removal of a sluice gate positioned at the center of a transversal wall forming the reservoir. Specifically, in order to understand the influence of tailwater level on wave propagation, three tests were conducted under the conditions of dry and wet downstream bottom with two different tailwater depths, respectively. The present research analyzes the propagation of the positive and negative wave originated by the dam-break, as well as the wave reflection against the channel’s downstream closed boundary. Digital image processing was used to track water surface patterns, and ultrasonic sensors were positioned at five different locations along the channel in order to obtain water stage hydrographs. Laboratory measurements were compared against the numerical results obtained through FLOW-3D commercial software, solving the 3D Reynolds-Averaged Navier–Stokes (RANS) with the k-ε turbulence model for closure, and Shallow Water Equations (SWEs). The comparison achieved a reasonable agreement with both numerical models, although the RANS showed in general, as expected, a better performance.

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