The Effectiveness of the Unit Cell Method in Numerically Modeling and Designing Liquid Cooled Heatsinks

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Ali C. Kheirabadi ◽  
Dominic Groulx
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Parametric Design ◽  
Unit Cell ◽  
Liquid Cooling ◽  
Cell Method ◽  
Numerical Predictions ◽  
Finite Element Package ◽  
Parametric Studies ◽  
Relative Differences

This study compares two numerical strategies for modeling flow and heat transfer through mini- and microchannel heatsinks, the unit cell approximation, and the full 3D model, with the objective of validating the former approach. Conjugate heat transfer and laminar flow through a 2 × 2 cm2 copper–water heatsink are modeled using the finite element package COMSOL Multiphysics 5.0. Parametric studies showed that as the heatsink channels’ widths were reduced, and the total number of channels increased, temperature and pressure predictions from both models converged to similar values. Relative differences as low as 5.4% and 1.6% were attained at a channel width of 0.25 mm for maximum wall temperature and channel pressure drop, respectively. Due to its computational efficiency and tendency to conservatively overpredict temperatures relative to the full 3D method, the unit cell approximation is recommended for parametric design of heatsinks with channels’ widths smaller than 0.5 mm, although this condition only holds for the given heatsink design. The unit cell method is then used to design an optimal heatsink for server liquid cooling applications. The heatsink has been fabricated and tested experimentally, and its thermal performance is compared with numerical predictions. The unit cell method underestimated the maximum wall temperature relative to experimental results by 3.0–14.5% as the flowrate rose from 0.3 to 1.5 gal/min (1.1–5.7 l/min).

Turbulent Heat Transfer Over a Free Rotating Disk: Analytical and Numerical Predictions Using Solutions of Direct and Inverse Problems

2001 ◽  
Author(s):  
I. V. Shevchuk
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Wall Temperature ◽  
Direct Problem ◽  
Rotating Disk ◽  
Analytical Form ◽  
Turbulent Heat Transfer ◽  
Radial Coordinate ◽  
Turbulent Heat ◽  
Numerical Predictions

Abstract All known analytical solutions of the integral equation of the turbulent thermal boundary layer for a rotating disk have been obtained for the case of direct problem. This means finding the Nusselt number at a given distribution of the wall temperature. This distribution is described by power law and is monotone (derivative of wall temperature with respect to the radial coordinate does not change its sign). Outlined in this paper is an analytical form of non-monotone distribution of the wall temperature, which provided a new analytical solution for the turbulent Nusselt number including earlier known equations as a specific particular case. The solution is based on the integral method, which proved to be more precise than known Dorfman’s approach. Chosen for validation of the proposed method were turbulent heat transfer experiments of Northrop and Owen (1988). Predictions presented include analytical studies using inverse and direct problem solutions as well as numerical simulations using polynomial approximations of the experimental wall temperature distributions.

scholarly journals Detailed CFD Modelling of Open Refrigerated Display Cabinets

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Pedro Dinis Gaspar ◽  
L. C. Carrilho Gonçalves ◽  
R. A. Pitarma
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Thermal Response ◽  
Experimental Tests ◽  
Cfd Modelling ◽  
Humidity Effect ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Parametric Studies ◽  
Flow Through

A comprehensive and detailed computational fluid dynamics (CFDs) modelling of air flow and heat transfer in an open refrigerated display cabinet (ORDC) is performed in this study. The physical-mathematical model considers the flow through the internal ducts, across fans and evaporator, and includes the thermal response of food products. The air humidity effect and thermal radiation heat transfer between surfaces are taken into account. Experimental tests were performed to characterize the phenomena near physical extremities and to validate the numerical predictions of air temperature, relative humidity, and velocity. Numerical and experimental results comparison reveals the predictive capabilities of the computational model for the optimized conception and development of this type of equipments. Numerical predictions are used to propose geometrical and functional parametric studies that improve thermal performance of the ORDC and consequently food safety.

A Comparison of Numerical Strategies for Optimal Liquid Cooled Heat Sink Design

2016 ◽  
Author(s):  
Ali C. Kheirabadi ◽  
Dominic Groulx
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Parametric Design ◽  
Three Dimensional ◽  
Primary Objective ◽  
Design Tool ◽  
Unit Cell ◽  
Channel Width ◽  
Pressure Drops ◽  
Temperature And Pressure

This study compares two common numerical strategies for modeling flow and heat transfer through mini- and micro-channel heat sinks: the unit cell approach and a complete three dimensional unified approach. Conjugate heat transfer and laminar flow through a copper-water heat sink over a 2×2 cm2 heat source have been modelled using the finite element method within COMSOL Multiphysics 5.0; with the primary objective being to identify the channel width at which the two models yield similar temperature and pressure predictions. Parametric studies that varied channel widths showed that as these widths were reduced, and the total number of channels increased, temperature and pressure predictions from both models converged to similar values. Relative differences as low as 5.4 and 1.6 % were attained at a channel width of 0.25 mm for maximum wall temperatures and channel pressure drops, respectively. Based upon its computational efficiency and conservative over prediction of wall temperatures, the unit cell approach is recommended as a superior design tool for parametric design studies at channel widths of less than 0.5 mm.

scholarly journals The Effect of Baffle Configuration on Heat Transfer and Pressure Drop Characteristics of Jet Impingement System with Cross-Flow

2021 ◽  
Vol 86 (2) ◽  
pp. 15-27
Author(s):  
Sabu Kurian ◽  
Tide P Sunny ◽  
Biju N
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Cross Flow ◽  
Jet Impingement ◽  
Hydraulic Performance ◽  
Performance Parameter ◽  
Numerical Predictions ◽  
Parametric Studies ◽  
Cross Flow Velocity ◽  
Plate Distance

Use of baffles in jet impingement systems in presence of initial cross-flow disturbs boundary layer that results in rise in heat transfer. Two configurations of baffle assisted impingement systems were considered and a comparative study on heat transfer and pressure drop is carried out based on operating parameters such as baffle clearance, blow ratio and h/D ratio using commercially available CFD package. Numerical predictions showed that both heat transfer and pressure drop in segmented configuration were higher than louvered configuration for all blow ratio employed in this study. Parametric studies showed that, thermo-hydraulic performance parameter is higher only for louvered configurations at low blow ratio. When cross-flow velocity is comparable with jet velocity, segmented baffles resulted in relatively higher thermo-hydraulic performance because of its higher heat transfer rate relative to the incurring pressure drop. An increase in clearance proportionally increases performance parameter. However, as jet to plate distance increases, thermo hydraulic performance declines significantly.

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