scholarly journals Header Shape Effect on the Inlet Velocity Distribution in Cross-Flow Double-Layered Microchannel Heat Sinks

Fluids ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 7
Author(s):  
Stefano Savino ◽  
Carlo Nonino
Keyword(s):  
Velocity Distribution ◽  
Cross Flow ◽  
Flow Distribution ◽  
Thermal Control ◽  
Heat Sinks ◽  
Shape Effect ◽  
Counter Flow ◽  
Ansys Fluent ◽  
Microchannel Heat Sinks ◽  
Header Design

Counter-flow double-layered microchannel heat sinks are very effective for thermal control of electronic components; however, they require rather complicated headers and flow maldistribution can also play a negative role. The cross-flow configuration allows a much simpler header design and the thermal performance becomes similar to that provided by the counter-flow arrangement if the velocity distribution in the microchannels is not uniform. The aim of this work is to show the possibility of achieving a favorable flow distribution in the microchannels of a cross-flow double-layered heat sink with an adequate header design and the aid of additional elements such as full or partial height baffles made of solid or porous materials. Turbulent RANS numerical simulations of the flow field in headers are carried out with the commercial code ANSYS Fluent. The flow in the microchannel layers is modeled as that in a porous material, whose properties are derived from pressure drop data obtained using an in-house FEM code. It is demonstrated that, with an appropriate baffle selection, inlet headers of cross-flow microchannel heat sinks yield velocity distributions very close to those that would allow optimal hotspot management in electronic devices.

scholarly journals Temperature Uniformity in Cross-Flow Double-Layered Microchannel Heat Sinks

Fluids ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 143
Author(s):  
Carlo Nonino ◽  
Stefano Savino
Keyword(s):  
Numerical Study ◽  
Cross Flow ◽  
Bottom Layer ◽  
Heat Sinks ◽  
Temperature Uniformity ◽  
Counter Flow ◽  
Microchannel Heat Sinks ◽  
Unequal Number ◽  
Flow Configurations ◽  
Header Design

An in-house finite element method (FEM) procedure is used to carry out a numerical study on the thermal behavior of cross-flow double-layered microchannel heat sinks with an unequal number of microchannels in the two layers. The thermal performance is compared with those yielded by other more conventional flow configurations. It is shown that if properly designed, i.e., with several microchannels in the top layer smaller than that in the bottom layer, cross-flow double-layered microchannel heat sinks can provide an acceptable thermal resistance and a reasonably good temperature uniformity of the heated base with a header design that is much simpler than that required by the counter-flow arrangement.

Flow Maldistribution Effects on the Temperature Uniformity in Double-Layered Microchannel Heat Sinks

2019 ◽  
Author(s):  
Carlo Nonino ◽  
Stefano Savino
Keyword(s):  
Thermal Resistance ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Total Mass ◽  
Cross Flow ◽  
Heat Sinks ◽  
Temperature Uniformity ◽  
Inlet Velocity ◽  
Microchannel Heat Sinks ◽  
Flow Maldistribution

Abstract A numerical investigation is carried out on the effects of flow maldistribution on the temperature uniformity and overall thermal resistance in double-layered microchannel heat sinks. Different flow maldistribution models accounting for the effects of some typical header designs are considered together with different combinations of the average inlet velocity in the two layers of microchannels for a given total mass flow rate. The numerical simulations are carried out using an in-house FEM procedure previously developed by the authors for the analysis of cross-flow microchannel heat exchangers.

Analysis of Flow Mal-Distribution in a Cross-Flow Heat Exchanger

2014 ◽  
Vol 592-594 ◽  
pp. 1428-1432 ◽  
Author(s):  
Krishna P. Mohan ◽  
Shekar M. Santosh ◽  
M. Ramakanth ◽  
M.R. Thansekhar ◽  
M. Venkatesan
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Cross Flow ◽  
Flow Distribution ◽  
Ansys Fluent ◽  
Commercial Code ◽  
Uniform Flow Distribution ◽  
Flow Heat ◽  
Channel Assembly ◽  
Uniform Fluid

Flow mal-distribution is defined as the non-uniform fluid flow distribution among the parallel channels having a common header. Flow mal-distribution is present in every header channel assembly. This mal-distribution has a significant effect on the performance of the heat exchanger by increasing the pressure drop and affecting the heat transfer characteristics. However, in designing a heat exchanger, a uniform flow distribution in each channel is assumed. The present work attempts to reduce the flow mal-distribution in a cross flow heat exchanger. A numerical analysis is done using a commercial code ANSYS FLUENT 3D and the results are validated experimentally. A parametric study is done by changing the size of the channels within the heat exchanger so as to reduce the flow mal-distribution. The effect of varying channel size on flow mal-distribution and pressure drop across the heat exchanger is studied and a geometry with reduced flow mal-distribution is found.

Optimisation of single and double layer counter flow microchannel heat sinks

2002 ◽  
Vol 22 (14) ◽  
pp. 1569-1585 ◽  
Author(s):  
S.H. Chong ◽  
K.T. Ooi ◽  
T.N. Wong
Keyword(s):  
Double Layer ◽  
Heat Sinks ◽  
Counter Flow ◽  
Microchannel Heat Sinks

Development of MEMS Microchannel Heat Sinks for Micro/Nano Spacecraft Thermal Control

2002 ◽  
Author(s):  
Anthony D. Paris ◽  
Gajanana C. Birur ◽  
Amanda A. Green
Keyword(s):  
Heat Sink ◽  
Thermal Control ◽  
Hydraulic Performance ◽  
Heat Sinks ◽  
Performance Criteria ◽  
Working Fluid ◽  
High Heat Flux ◽  
Microchannel Heat Sink ◽  
Microchannel Heat Sinks ◽  
Spacecraft Thermal Control

MEMS-based microchannel heat sinks are being investigated at the Jet Propulsion Laboratory (JPL) for use in micro/nano spacecraft thermal control. The current stage of development focuses on the integration of microchannel heat sinks into spacecraft pumped cooling loops. Two microchannel heat sinks, adapted from a Stanford University Microfluidics Laboratory design, were fabricated at JPL and tested for thermal and hydraulic performance in a single-phase pumped cooling loop. The first microchannel heat sink design was demonstrated to remove heat fluxes of up to 25 W/cm2 with a maximum device temperature of less than 80 °C. Both the original and redesigned heat sinks where shown to meet hydraulic performance criteria requiring less than 1 psi pressure drop with water as the working fluid. It was concluded that the design methodology developed for this project produces microchannel heat sink devices capable of high heat flux removal in future micro/nano spacecraft thermal control architecture.

Convective Heat Transfer of Parallel-Flow and Counter-Flow Double-Layer Microchannel Heat Sinks in Staggered Arrangement

2017 ◽  
Author(s):  
Han Shen ◽  
Yingchun Zhang ◽  
Hongbin Yan ◽  
Bengt Sunden ◽  
Gongnan Xie
Keyword(s):  
Heat Transfer ◽  
Double Layer ◽  
Electronic Devices ◽  
Structure Design ◽  
Parallel Flow ◽  
Heat Sinks ◽  
Counter Flow ◽  
Microchannel Heat Sinks ◽  
Staggered Arrangement ◽  
Flow Case

Previous research has proved Double-layer Microchannel Heat Sinks (MHSs) to be efficient ways to improve the cooling performance of electronic devices. However, the cooling potential of the upper working liquid cannot be fully utilized to cool down the substrate with the heated elements. In this sense, a concept of staggered double-layer MHS is proposed and designed. The parallel and counter flow directions are considered to investigate the flow arrangement effect. The Reynolds number effect, Nusselt number and pressure drop are analyzed in detail and compared with those of a parallel straight double-layer MHS. It is found that the staggered double-layer MHSs exhibit much better heat transfer enhancement and overall thermal performance compared with the parallel straight double-layer MHS. For the staggered double-layer MHSs, the counter flow case is superior to the parallel flow case. This research provides a new structure design to enhance the heat transfer in microchannel heat sinks and broad application prospects for heat sinks in the thermal management of high power density electronic devices.

scholarly journals Numerically Investigating the Effects of Cross-Links in Scaled Microchannel Heat Sinks

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Minh Dang ◽  
Ibrahim Hassan ◽  
Sung In Kim
Keyword(s):  
Pressure Drop ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Heat Sinks ◽  
Straight Channel ◽  
Two Phase ◽  
Microchannel Heat Sinks ◽  
Cross Links ◽  
Channel Configuration

Thermal management as a method of heightening performance in miniaturized electronic devices using microchannel heat sinks has recently become of interest to researchers and the industry. One of the current challenges is to design heat sinks with uniform flow distribution. A number of experimental studies have been conducted to seek appropriate designs for microchannel heat sinks. However, pursuing this goal experimentally can be an expensive endeavor. The present work investigates the effect of cross-links on adiabatic two-phase flow in an array of parallel channels. It is carried out using the three-dimensional mixture model from the computational fluid dynamics software, FLUENT 6.3. A straight channel and two cross-linked channel models were simulated. The cross-links were located at 1/3 and 2/3 of the channel length, and their widths were one and two times larger than the channel width. All test models had 45 parallel rectangular channels, with a hydraulic diameter of 1.59 mm. The results showed that the trend of flow distribution agrees with experimental results. A new design, with cross-links incorporated, was proposed and the results showed a significant improvement of up to 55% on flow distribution compared with the standard straight channel configuration without a penalty in the pressure drop. Further discussion about the effect of cross-links on flow distribution, flow structure, and pressure drop was also documented.

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