Experimental investigations on heat transfer in a new minichannel heat sink (original) (raw)
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This study experimentally investigated heat transfer and pressure drop on tube side of a mini-channel shell and tube heat exchanger (MC-STHE) prototype designed and manufactured using Kern method. Mini-channel copper tubes with an inner diameter of 2 mm and a length of 240 mm were used on the tube side of the MC-STHE. Baffles with a 25% baffle cut and a shell with an inner diameter of 30 mm were used on the shell side. The Reynolds number on the tube side was changed from 1000 to 10,000 while that on the shell side was kept constant at 680. The experimental convective heat transfer coefficients and friction factors for the tube side were compared with correlations for macro-pipes commonly used in the literature. The experimental convective heat transfer coefficients were in good agreement with the Shah and Sieder-Tate correlations in the laminar region and in good agreement with the Petukhov, Hausen and Gnielinski correlations in the transition region while the experimental friction factors showed a similar tendency to the correlation modified by Shah. In addition, the Nusselt number and friction factor correlations have been proposed for use in designing similar MC-STHEs. The optimal operating range of Reynolds number for MC-STHEs is 4000 < Re <5000 based on the Colburn factor while it is 4000 < Re <6000 based on the flow area goodness factor.
Fluid Flow and Thermal Characteristics of a Minichannel Heat Sink with Impinging Air Flow
Arabian Journal for Science and Engineering, 2012
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Experimental investigation of heat transfer performance for a novel microchannel heat sink
Journal of Micromechanics and Microengineering, 2008
ABSTRACT Optimization of heat transfer management is a key issue in designing a combustion chamber. Film cooling is one of the most effective cooling methods used in combustion chambers of liquid propellant rocket engines. The reliable construction und dimensioning of this cooling method requires detailed knowledge of the all processes which govern the heat transfer under real rocket engine operating conditions. This paper presents the test specimen and the measurement technique that has been developed und successfully used by the Institute of Space Propulsion for investigations of the influence of injector-wall interactions on heat transfer in a subscale combustion chamber as well the measurement results. The presented investigations have been performed at the European Research and Technology Test Facility P8 for cryogenic subscale rocket engines.
Study of thermal and hydraulic performance of air cooled minichannel heatsink with novel geometries
International Communications in Heat and Mass Transfer, 2019
Numerical and experimental study of minichannel heat sinks (MCHS), with air as a cooling medium, has been performed for straight channel heatsink (SC HS), wavy channel heatsink (WC HS) and branch wavy channel heatsink (BWC HS) to investigate thermal and hydraulic performances. After considering both the conduction and the convection as a mode of heat transfer, numerical computation of three-dimensional conjugated heat transfer between the heat sink and air flow has been performed by using full domain simulation in ANSYS Fluent. Laminar model is selected for the study of air flow and heat transfer as the Reynolds number varied from 300 to 1900 for a different range of air flow rates. Heating powers of 20 watt and 30 watt are applied at the base of the heat sink. Followed by detailed experimentation, the numerical results are also examined to get acquainted with the flow fields and their roles in the thermal performance of individual heat sinks. It has been found that the thermal-hydraulic performance factor of BWC HS exhibited superiority over SC HS and WC HS. It is also noticed that significant improvements in the junction temperature of BWC HS have been achieved. Experimental results have been validated with numerical results.
Applied Thermal Engineering, 2009
With the rapid development of the information technology (IT) industry, the heat flux in integrated circuit (IC) chips cooled by air has almost reached its limit about 100 W/cm 2. Some applications in high technologies require heat fluxes well beyond such a limitation. Therefore the search of a more efficient cooling technology becomes one of the bottleneck problems of the further development of IT industry. The microchannel flow geometry offers large surface area of heat transfer and a high convective heat transfer coefficient. However, it has been hard to implement because of its very high pressure head required to pump the coolant fluid though the channels. A normal channel could not give high heat flux although the pressure drop is very small. A minichannel can be used in heat sink with a quite high heat flux and a mild pressure loss. A minichannel heat sink with bottom size of 20 mm  20 mm is analyzed numerically for the single-phase laminar flow of water as coolant through small hydraulic diameters and a constant heat flux boundary condition is assumed. The effects of channel dimensions, channel wall thickness, bottom thickness and inlet velocity on the pressure drop, thermal resistance and the maximum allowable heat flux are presented. The results indicate that a narrow and deep channel with thin bottom thickness and relatively thin channel wall thickness results in improved heat transfer performance with a relatively high but acceptable pressure drop. A nearly-optimized configuration of heat sink is found which can cool a chip with heat flux of 256 W/cm 2 at the pumping power of 0.205 W. The nearly-optimized configuration is verified by an orthogonal design. The simulated thermal resistance agrees quite well with the result of conventional correlations method with the maximum difference of 12%.
This study experimentally investigated the shell side heat transfer and pressure drop of a mini-channel shell and tube heat exchanger (MC-STHE) designed and manufactured using Kern's method. A shell with an inner diameter of 30 mm and four horizontally oriented transverse baffles with a 25% baffle cut were used in the mini-channel heat exchanger. Using rotated triangular layout, the tube bundle was composed of 13 mini-channel copper tubes with an outer diameter of 3 mm and a length of 240 mm. The shell-side Reynolds numbers ranged from 250 to 2500 while the tube-side Reynolds number was kept constant at $5900 based on the experimental surface flow area goodness factor (j/f) results. The shell side convective heat transfer coefficients and total pressure drop results were compared with correlations for macro tubes commonly used in the literature. The experimental convective heat transfer coefficients were in good agreement with the Kern design, VDI-HA and McAdam's correlations within the Reynolds numbers ranging from 250 to 2500. The experimental total pressure drop of the MC-STHE was 2.3 times higher than that of macro tube heat exchangers. In addition, the Nusselt number and Colburn factor correlations were proposed for the estimation of shell side convective heat transfer coefficient in MC-STHEs. The optimum working range for shell side is Re < 1000 according to surface flow area goodness factor by which heat transfer and hydrodynamic effects in MC-STHE are evaluated together.
Nihon Kikai Gakkai Ryutai …, 2006
The authors have reported that minichannel flow system had high heat transfer coefficient. We investigated experimentally and numerically the heat transfer and flow structure of single and array minichannel combined with impingement flow system. The diameter D of the channel was 1.27 mm and length to diameter ratio L/D was 5. The minichannel array was so called shower head which was constructed by 19 minichannels located at the apex of equilateral triangle, the side length S of which was 4 mm. The mechanism of high heat transfer was studied numerically by the Reynolds averaged Navier-Stokes equation and k-.OMEGA. turbulence model. The limiting streamline pattern was correlated well to the surface heat flux distribution. The high heat transfer in the single minichannel was achieved by suppressing the development of boundary layer under strong pressure gradient near the channel inlet and by the formation of large recirculating flow system in the downstream plenum of the minichannel exit. These heat transfer mechanisms became dominant when the channel size fallen into the regime of minichannel. The heat transfer performance of minichannel array was equivalent to that of impingement jet.
Iranian Journal of Chemistry & Chemical Engineering-international English Edition, 2018
In this paper, the cooling performance of water-cooled heat sinks for heat dissipation from electronic components is investigated numerically. Computational Fluid Dynamics (CFD) simulations are carried out to study the rectangular and circular cross-sectional shaped heat sinks.The sectional geometry of channels affects the flow and heat transfer characteristics of minichannel heat sinks. The three-dimensional governing equations in steady state and laminar flow are solved using Finite Volume Method (FVM) with the SIMPLE algorithm. The results show that the numerical simulation is in good agreement with the experimental data. The thermal and hydrodynamic characteristics of the heat sinks including Nusselt number, friction factor, thermal resistance and pumping power for various geometries of heat sinks are discussed in details. The results indicate that the heat sink with rectangular cross-section has a better heat transfer rate and the circular channel heat sink has the lower pumping power.
Heat transfer augmentation in microchannel heat sink using secondary flows: A review
International Journal of Heat and Mass Transfer, 2022
A three-dimensional numerical simulation was conducted to study the characteristics of fluid flow and heat transfer in new design of microchannel heat sink with sinusoidal cavities and rectangular ribs (MC-SCRR) for Reynolds number ranging from 100 to 800. A comparative analysis has conducted to the performance of the proposed design with related geometries such as microchannel with rectangular ribs MC-RR and microchannel with sinusoidal cavities MC-SC. The results showed that thermal performance of MC-SCRR is superior over both MC-RR and MC-SC. The new design of MC-SCRR has proved the ability to combine between two important features; large flow area which significantly reduces the pressure drop and high flow disturbances which caused by existence of ribs in the central portion of channel. The overall performance of MC-SCRR is evaluated in term of friction factor, Nusselt number and performance factor. The effect of three geometrical parameters; relative cavity amplitude (k) relative rib width (b) and relative rib length (C) on the convective heat transfer and pressure drop have been investigated. The performance factor Pf for MC-SCRR with k = 0.15, b = 0.13 and C = 0.5 achieves 1.85 at Re = 800.