Optimization of Pin-Fin Heat Sinks in Bypass Flow Using Entropy Generation Minimization Method

Abstract

An entropy generation minimization, EGM, method is applied to study the thermodynamic losses caused by heat transfer and pressure drop for the fluid in a cylindrical pin-fin heat sink and bypass flow regions. A general expression for the entropy generation rate is obtained by considering control volumes around heat sink and bypass regions. The conservation equations for mass and energy with the entropy balance are applied in both regions. Inside the heat sink, analytical/empirical correlations are used for heat transfer coefficients and friction factors, where the reference velocity used in Reynolds number and pressure drop is based on the minimum free area available for the fluid flow. In bypass regions theoretical models, based on laws of conservation of mass, momentum and energy, are used to predict flow velocity and pressure drop. Both in-line and staggered arrangements are studied and their relative performance is compared for the same thermal and hydraulic conditions. A parametric study is also performed to show the effects of bypass on the overall performance of heat sinks.

Numerical Evaluation of Flow and Heat Transfer in Plate-Pin Fin Heat Sinks with Various Pin Cross-Sections

“…Chen et al [18] developed an effective method for performing the thermal optimization of fully confined pin fin heat sinks under constraints of pressure drop, mass, and space limitations. Khan et al [19,20] studied the thermodynamic losses caused by heat transfer and pressure drop in cylindrical pin fin heat sinks by applying an entropy generation minimization (EGM) technique, which allows all relevant design parameters for pin-fin heat sinks, including geometric parameters, material properties and flow conditions, to be simultaneously optimized. Chiang et al [21,22] explored the optimal values of designing parameters of a pin fin type heat sink under constrains of mass and space limitation to achieve high thermal performance (or cooling efficiency) by experiment.…”

Entropy generation and optimization of laminar convective heat transfer and fluid flow in a microchannel with staggered arrays of pin fin structure with tip clearance

“…The authors [20] further found that increasing side/top clearance reduces the dimensionless entropy generation rate. Famouri et al [33] reported the effects of fin size, spacing and tip clearance.…”

“…The heat transfer rate experienced a 40% decrease when C/H increases from 0 to 1 at this optimum spacing. Khan et al [20] indicated that the increase in fin tip clearance (0.25 6 C/H 6 1) resulted in an increase in thermal resistance and a decrease in pressure drop for cases with a channel-height-topin-fin-diameter ratio, (C + H)/D, of 12.5. The impact of tip clearance on pressure drop and heat transfer was reported by Moores et al [21].…”

Optimization of heat exchangers of refrigeration machines by entropy generation minimization method

“…Такая оптимизация возможна только с применением термодинамического анализа методом минимизации производства энтропии. Работы [12][13][14] принадлежат группе исследователей лаборатории микроэлектро-ники Университета Ватерлоо (Канада). В работах рассмотрена оптимизация компактных оребренных микроканальных охладителей методом минимиза-ции производства энтропии.…”