Shape Optimization of Micro-channel Heat Sink for Micro-electronic Cooling

Afzal Husain(후세인아프잘),Kwang-Yong Kim(김광용) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-

A numerical investigation of three dimensional fluid flow and heat transfer in a rectangular micro-channel has been carried out using water as a cooling fluid in a silicon substrate. Navier-Stokes and energy equations for laminar flow and conjugate heat transfer are solved using a finite volume solver. Solutions are first carefully validated with the experimental results available; the shape of the micro-channel is then optimized using surrogate methods. Ratios of width of the micro-channel to depth and width of the fin to depth are selected as design variables. Design points are selected through three level D-optimal designs. A single objective function thermal resistance, formulated using pumping power as constraint, is optimized. Response surface analysis, Kriging and Radial basis neural network methods are applied to construct surrogates and the optimum point is searched by sequential quadratic programming.

Numerical Analysis of Electroosmotically Enhanced Microchannel Heat Sinks

후세인 아프잘(Afzal Husain),김광용(Kwang-Yong KIM) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

A micro channel heat sink has been studied and optimized for mixed pressure driven and electroosmotic flows through three-dimensional numerical analysis. The effects of ionic concentration represented by zeta potential and Debye thickness are studied with the various steps of externally applied electric potential. Optimization of the micro channel heat sink has been performed considering two design variables related to the micro channel width, depth and fin width. The surrogate-based optimization is performed using a search algorithm taking overall thermal resistance as objective function. The thermal resistance is found to be more sensitive to channel width-to-depth ratio than fin width-to-depth of channel ratio.

사다리꼴 미세유로의 형상최적화

후세인 아프잘(Afzal Husain),김광용(Kwang-Yong Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

This work presents microchannel heat sink shape optimization procedure using Kriging method. Design variables relating to microchannel width, depth and fin width are selected, and thermal resistance has been taken as objective function. Design points are selected through a three-level fractional factorial design of sampling method. Navier-Stokes and energy equations for laminar flow and conjugate heat transfer are solved at these design points using a finite volume solver. Solutions are carefully validated with experimental results. Using the numerically evaluated objective function, a surrogate model (Kriging) is constructed and optimum point is searched by sequential quadratic programming. The process of shape optimization greatly improves the thermal performance of microchannel heat sink under constant pumping power.

Heat Sink Analysis for Electronic Cooling with Variable Fluid Properties

아프잘 후세인(Afzal Husain),김광용(Kwang-Yong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Advanced ultra large-scale integration (ULSI) technologies, and stacking of high performance microprocessors have resulted in growing requirements for higher heat flux removal. Liquid flow microchannel heat sink integrated at the chip surface has been proposed for the viable solution for this cooling problem. The present study deals with the three-dimensional numerical fluid flow and heat transfer analysis. The study highlights the basic issues pertaining to the microflow simulation and covers essential aspects of accurately predicting the fluid flow and heat transfer phenomena in a microchannel heat sink. The microchannels with smooth walls are investigated to heat transfer performance in terms of pumping power and thermal resistance. The design variables effective to the performance of the microchannel heat sink have been investigated and optimized with the help of surrogate analysis. The effect of various design variables to the objective function which is a composite form of thermal resistance and pumping power is studied and the sensitivities of the objective function to design variables are investigated.

핀휜이 부착된 회전하는 냉각유로의 최적설계

문미애(Mi-Ae Moon),아프잘 후세인(Afzal Husain),김광용(Kwang-Yong Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

This paper presents numerical optimization of the design of a rotating rectangular channel with staggered arrays of pin-fins with Kriging metamodeling technique. Two non-dimensional variables, the ratio of the height to diameter of the pin-fin and the ratio of the spacing between the pin-fins to diameter of the pin-fins are chosen as design variables. The objective function as a linear combination of heat transfer and friction loss related terms with a weighting factor is selected for the optimization. Objective function values at twenty training points generated by Latin hypercube sampling (LHS) are evaluated by three-dimensional Reynolds-averaged Navier-Stokes (RANS) method with the shear stress transport (SST) turbulence model. The prediction of objective function by Kriging metamodeling at optimum point shows reasonable accuracy in comparison with the values calculated by RANS analysis. With increase in height of the pin-fin, heat transfer is decreased and at the same time pressure drop is also decreased, while opposite behavior is obtained for the pin-fin spacing.

핀휜이 부착된 회전하는 냉각유로의 최적설계

문미애(Mi-Ae Moon),아프잘 후세인(Afzal Husain),김광용(Kwang-Yong Kim) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.7

본 연구에서는 크리깅 기법을 이용하여 엇갈린 핀휜이 부착된 회전하는 내부냉각유로의 형상 최적화를 수행하였다. 냉각유로 형상의 여러 매개변수 중 핀의 지름과 높이의 비, 핀의 지름과 핀과 핀 사이의 거리의 비를 최적설계를 위한 설계변수로 선택하였다. 열전달 관련 목적함수와 마찰손실 관련 목적함수를 가중계수를 이용하여 선형적으로 결합한 목적함수를 정의하였다. 크리깅 모델을 구축하기 위해 라틴하이퍼큐브 샘플링기법에 의해 생성된 20개 실험점에서 목적함수가 SST난류모델을 사용한 삼차원 레이놀즈평균 나비어-스톡스(RANS) 유동해석법에 의해 계산되었다. 크리깅 기법을 통하여 예측된 목적함수값은 RANS해석을 이용해 계산된 값과 매우 작은 오차 범위 내에서 일치하였으며, 최적설계를 통해 목적함수가 11% 감소하는 결과를 얻었다. This paper describes the design optimization of a rotating rectangular channel with staggered arrays of pin-fins by Kriging metamodeling technique. Two non-dimensional variables, the ratio of the height to the diameter of the pin-fins and the ratio of the spacing between the pin-fins to the diameter of the pin-fins are chosen as the design variables. The objective function that is a linear combination of heat transfer and friction loss related terms with a weighting factor is selected for the optimization. To construct the Kriging model, objective function values at 20 training points generated by Latin hypercube sampling are evaluated by a three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis method with the SST turbulence model. The Kriging model predicts the objective function value that agrees well with the value calculated by the RANS analysis at the optimum point. The objective function is reduced by 11% by the optimization of the channel.

다중목적 최적화기법을 이용한 원심압축기 임펠러 설계

김진혁(Jin-Hyuk Kim),최재호(Jae-Ho Choi),후세인 아프잘(Afzal Husain),김광용(Kwang-Yong Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

This paper presents a design optimization of a centrifugal compressor impeller with hybrid multi-objective evolutionary algorithm (hybrid MOEA). Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by finite volume approximations and solved on hexahedral grids for flow analyses. Two objectives, i.e., isentropic efficiency and total pressure ratio are selected with four design variables defining impeller hub and shroud contours in meridional contours to optimize the system. Non-dominated Sorting of Genetic Algorithm (NSGA-Ⅱ) with ε-constraint strategy for local search coupled with Radial Basis Neural Network model is used for multi-objective optimization. The optimization results show that isentropic efficiencies and total pressure ratios of the five cluster points at the Pareto-optimal solutions are enhanced by multi-objective optimization.