Investigation of Flow and Heat Transfer Performance of Double-Layer Pin-Fin Manifold Microchannel Heat Sinks

At a Glance

Metadata	Details
Publication Date	2022-10-05
Journal	Water
Authors	Yantao Li, Qianxiang Wang, Ming‐Han Li, Xizhen Ma, Xiu Xiao
Institutions	Nanjing Boiler and Pressure Vessel Inspection Institute, Dalian Maritime University
Citations	9
Analysis	Full AI Review Included

Technical Documentation & Analysis: Double-Layer Pin-Fin MMC Heat Sinks

Executive Summary

This analysis focuses on the numerical investigation of Double-Layer Pin-Fin Manifold Microchannel (MMC) heat sinks designed for high-flux electronic cooling, specifically targeting heat loads of 100 W/cm². The findings highlight critical geometric optimizations, which, when combined with 6CCVD’s advanced MPCVD diamond materials, offer a pathway to next-generation thermal management solutions.

High-Flux Application: The study validates a structure capable of managing extreme heat fluxes (100 W/cm²), a critical requirement for high-power chips and micro-electro-mechanical systems (MEMS).
Performance Enhancement: The double-layer design significantly improves comprehensive performance, achieving up to 35.2% lower pressure drop and superior temperature uniformity compared to single-layer MMCs.
Optimal Geometry: Round pin-fins demonstrated the minimal thermal resistance and best comprehensive performance index (ζ) across the tested inlet velocity range (1.2 m/s to 3.6 m/s).
Thermal Resistance Challenge: While performance is improved, the thermal resistance (R_eff) remains relatively high (up to 7.5 K/W). This resistance is dominated by the base material and convective heat transfer limitations.
6CCVD Value Proposition: Utilizing 6CCVD’s Single Crystal Diamond (SCD) material (Thermal Conductivity: up to 2200 W/m·K) is the definitive method to drastically reduce the base thermal resistance component, enabling R_eff values approaching 0.1 K/W for similar high-flux applications.
Custom Fabrication: 6CCVD offers the necessary custom dimensions and material purity required to fabricate or integrate these complex pin-fin microchannel structures directly into high-purity diamond substrates.

Technical Specifications

The following hard data points were extracted from the numerical simulation and validation models:

Parameter	Value	Unit	Context
Applied Heat Flux (q)	100	W/cm²	Uniform heat source at bottom boundary
Working Fluid	Deionized Water	N/A	Incompressible flow
Inlet Temperature (T_in)	293.15	K	Standard operating condition
Inlet Velocity Range (u)	1.2 to 3.6	m/s	Range for performance analysis
Thermal Resistance (R_eff)	2.5 to 7.5	K/W	Dependent on velocity and pin-fin size
Max Temperature Difference (ΔT)	3.0 to 6.0	K	Measure of temperature uniformity
Pressure Drop Reduction	Up to 35.2	%	Double-layer vs. single-layer MMC
Optimal Pin-Fin Shape	Round	N/A	Demonstrated best comprehensive performance
Pin-Fin Diameter (d) Range	0.4 to 1.1	mm	Range investigated for size optimization
Microchannel Depth (l_d)	150	µm	Validation model parameter
Height Ratio (α = H₂/H₁) Range	0.4 to 1.2	N/A	Ratio of upper to lower layer height

Key Methodologies

The study employed Computational Fluid Dynamics (CFD) to analyze the thermal-hydraulic performance of the double-layer pin-fin MMC structure.

Simulation Environment: Numerical simulations were conducted using the commercial software ANSYS Fluent 2020R2.
Meshing Strategy: Polyhedral meshes were generated using FLUENT meshing, with five refined boundary layers near the walls to accurately capture fluid dynamics. A grid independence analysis confirmed stability at 594,758 elements.
Governing Equations: The continuity, momentum (Navier-Stokes), and energy equations were solved, utilizing the reliable k-ε turbulence model due to the high turbulence induced by the pin-fins and multi-inlet jet effects.
Geometric Parameter Variation:
- Pin-Fin Shape: Compared Round, Diamond-shaped, and Rectangular cross-sections (with equivalent circumscribed circle diameters).
- Pin-Fin Size: Diameter (d) of the round pin-fin was varied from 0.4 mm to 1.1 mm.
- Height Ratio (α): The ratio of upper layer height (H₂) to lower layer height (H₁) was varied from 0.4 to 1.2.
Performance Metrics: Performance was evaluated using the effective thermal resistance (R_eff), maximum temperature difference (ΔT), pressure drop (ΔP), and the comprehensive performance index (ζ), which balances the Colburn factor (j) and the Fanning friction factor (f).

6CCVD Solutions & Capabilities

The research demonstrates the viability of complex microchannel geometries for high-flux cooling. However, achieving the necessary ultra-low thermal resistance required for next-generation electronics demands materials with intrinsic thermal properties far exceeding conventional heat sink substrates (Si, Cu). 6CCVD provides the necessary MPCVD diamond solutions to elevate this research from simulation to market-leading performance.

Applicable Materials

To replicate and significantly extend the performance of this double-layer pin-fin MMC structure, 6CCVD recommends the following materials:

6CCVD Material	Application Focus	Key Advantage for 100 W/cm² Flux
Optical Grade Single Crystal Diamond (SCD)	Base Substrate & Heat Spreader	Thermal Conductivity up to 2200 W/m·K. Directly minimizes the thermal resistance of the heat sink base (R_b), which is critical for high-flux applications.
Polycrystalline Diamond (PCD)	Large Area Heat Sinks & Plates	Available in plates up to 125mm. Ideal for large-area chip cooling where the heat sink itself must be fabricated from diamond.
Boron-Doped Diamond (BDD)	Integrated Electrodes/Sensors	If the system requires integrated temperature sensing or electrochemical functionality within the fluid channels.

Customization Potential

The double-layer pin-fin MMC design requires precise micro-fabrication and specific dimensions that align perfectly with 6CCVD’s custom capabilities:

Custom Dimensions and Thickness: The study utilizes microchannel depths of 150 µm. 6CCVD can supply SCD or PCD wafers with thicknesses ranging from 0.1 µm up to 500 µm, and substrates up to 10 mm thick, allowing for the fabrication of both the microchannel layers (H₁, H₂) and the manifold divider layer in high-purity diamond.
Complex Geometry Fabrication: The round pin-fin structure (0.4 mm to 1.1 mm diameter) requires high-precision material removal. 6CCVD offers advanced laser cutting and etching services to create these complex, high-aspect-ratio pin-fin geometries directly into the diamond substrate with sub-micron accuracy.
Metalization Services: While the paper focuses on fluid dynamics, practical integration requires robust bonding and electrical interfaces. 6CCVD offers in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu) for creating reliable interfaces between the diamond heat sink and the electronic component or external plumbing.

Engineering Support

The authors of the paper correctly advise that further experimental validation is needed. 6CCVD’s in-house PhD team specializes in thermal management and material science, offering expert consultation to researchers and engineers tackling similar High-Power Chip Cooling projects. We assist in:

Optimizing diamond material grade selection based on specific thermal and mechanical requirements.
Designing optimal microchannel and pin-fin geometries for diamond substrates, leveraging diamond’s unique thermal properties.
Providing technical data and support for integrating diamond heat sinks into existing fluidic systems.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The manifold microchannel (MMC) heat sink is characterized by high heat transfer efficiency, high compactness, and low flow resistance. It can be an effective method for the high-flux removal of high-power electronic components. To further enhance the performance of the MMC, a double-layer pin-fin MMC structure was designed. The thermodynamic properties, including the flow and heat transfer characteristics, were numerically investigated using ANSYS Fluent with deionized water as the working liquid. Compared with the single-layer MMC, the temperature uniformity is better, the pressure drop is lower, and the comprehensive performance is improved at the cost of slightly larger thermal resistance for the double-layer MMC. The geometric effects on the thermodynamic performance were also analyzed. The results show that among the pin-fin structures with round, diamond-shaped, and rectangular cross-sections, the round pin-fins demonstrate the best comprehensive performance and the minimal thermal resistance. Under the same inlet velocity, the thermal resistance is decreased, and the comprehensive performance is first increased and then decreased as the pin-fin size increases. In addition, it is recommended to adopt a larger height ratio for low inlet velocity and a smaller height ratio for high inlet velocity.

Tech Support

Original Source

DOI: https://doi.org/10.3390/w14193140

References

2017 - Pressure-driven liquid-liquid separation in Y-shaped microfluidic junctions [Crossref]
2018 - Liquid-liquid extraction of calcium using ionic liquids in spiral microfluidics [Crossref]
2022 - Embedded microfluidic cooling with compact double H type manifold microchannels for large-area high-power chips [Crossref]
2022 - Investigation on the heat transfer and energy-saving performance of microchannel with cavities and extended surface [Crossref]
2006 - Cramming more components onto integrated circuits. Reprinted from Electronics, Volume 38, Number 8, April 19, 1965, p. 114 [Crossref]
2018 - Embedded Two-Phase Cooling of High Flux Electronics via Press-Fit and Bonded FEEDS Coolers [Crossref]
2021 - The Experimental Study of the Performance of Zigzag Microchannel Exchanger
2014 - Numerical simulation of flow and heat transfer in spaced fan-shaped cavity microchannels
2014 - Bionic modeling of tree-shaped microchannel heat sink and numerical analysis of 3D heat flow characteristics