Numerical Investigation of Fluid Flow and Heat Transfer in High-Temperature Wavy Microchannels with Different Shaped Fins Cooled by Liquid Metal

At a Glance

Metadata	Details
Publication Date	2023-07-02
Journal	Micromachines
Authors	Tingfang Yu, Xing Guo, Yicun Tang, Xuan Zhang, Lizhi Wang
Institutions	Beijing Institute of Technology, Nanchang University
Citations	7
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Performance Diamond Microchannel Heat Sinks

This document analyzes the research “Numerical Investigation of Fluid Flow and Heat Transfer in High-Temperature Wavy Microchannels with Different Shaped Fins Cooled by Liquid Metal” (Micromachines 2023, 14, 1366) to provide technical specifications and demonstrate how 6CCVD’s MPCVD diamond solutions offer superior performance for high-density heat flux applications.

Executive Summary

This study validates advanced microchannel designs for extreme heat dissipation, a critical requirement for modern power electronics and aerospace systems.

Application Focus: Numerical investigation of fluid flow and heat transfer in high-temperature wavy microchannels cooled by liquid lithium (Li).
Substrate Limitation: The study utilized Silicon Carbide (SiC) as the substrate material, which has a thermal conductivity ($\lambda_s$) of only 80 W/(m·K).
Optimal Geometry: Diamond-shaped fins yielded the best heat transfer augmentation, increasing the average Nusselt number (Nu) by 61.7% across the tested Reynolds number (Re) range (117.1 to 410.0).
Performance Trade-off: The enhanced heat transfer came with a significant penalty; the pressure drop ($\Delta p$) increased by as much as 7.5 times compared to the smooth straight channel.
Design Implication: Successful implementation of these high-performance microchannel designs requires a substrate material with vastly superior thermal conductivity to manage the high heat flux (200 W/cm²) and thermal gradients.
6CCVD Advantage: 6CCVD specializes in MPCVD diamond, offering thermal conductivity up to 2000 W/(m·K). Utilizing diamond substrates instead of SiC provides a 25x improvement in heat spreading, dramatically lowering the base temperature (T_w) and maximizing the overall performance factor ($\eta$).

Technical Specifications

Hard data extracted from the numerical investigation.

Parameter	Value	Unit	Context
Substrate Material Used	Silicon Carbide (SiC)	N/A	Thermal conductivity $\lambda_s = 80$ W/(m·K)
Coolant Fluid	Liquid Lithium (Li)	N/A	Used for high-temperature cooling
Applied Heat Flux (q”)	200	W/cm²	Uniform and constant heating at the bottom surface
Inlet Temperature (T_in)	600	K	High-temperature operating condition
Reynolds Number Range (Re)	117.1 to 410.0	N/A	Laminar flow regime
Microchannel Length (L)	20	mm	Overall heat sink dimension
Microchannel Height (H_c)	3	mm	Rectangular cross-section
Max Nu Increase	61.7	%	Achieved by wavy channel with diamond fins (Re 117.1 to 410.0)
Max Pressure Drop ($\Delta p$) Increase	7.5	times	Penalty associated with diamond-shaped fins
Optimal Fin Geometry	Diamond-shaped	N/A	Highest heat transfer augmentation
Optimal Fin Relative Height Ratio	> 0.4	N/A	Heat transfer enhancement dominates friction drag

Key Methodologies

A concise outline of the experimental setup and simulation parameters used in the research.

Physical Model: A 3D microchannel heat sink model (L=20 mm, W=20 mm, H=5 mm) was constructed on a Silicon Carbide substrate, featuring six parallel microchannels.
Channel Configurations: Four configurations were investigated: smooth straight, bare wavy, and wavy channels incorporating circular, square, and diamond-shaped fins.
Coolant and Flow: Liquid Lithium was selected as the coolant. The flow was modeled as laminar and steady-state, consistent with the Re range (117.1 to 410.0).
Thermal Boundary Conditions: A uniform and constant heat flux (q” = 200 W/cm²) was applied to the bottom surface (z=0). The inlet fluid temperature was fixed at 600 K.
Geometric Parameter Study: The influence of fin relative size (0.2 to 1.0) and fin relative height (0.2 to 1.0) on the overall performance factor ($\eta$) was systematically analyzed using the square-shaped fin configuration.
Numerical Procedure: Simulations were performed using ANSYS Fluent 19.0. Grid independence was verified, with final meshes ranging from 1.37 to 1.67 million hexahedral cells for the wavy fin channels.

6CCVD Solutions & Capabilities

The research demonstrates that microchannel geometry (specifically diamond fins) is highly effective for heat transfer augmentation, but the overall performance is limited by the substrate’s thermal conductivity. 6CCVD provides the necessary MPCVD diamond materials to overcome this limitation, enabling the full potential of these advanced microchannel designs.

Research Requirement	6CCVD Material Recommendation	6CCVD Technical Capability
Extreme Heat Spreading (Required to manage 200 W/cm²)	Optical Grade Single Crystal Diamond (SCD)	SCD offers thermal conductivity up to 2000 W/(m·K), providing a 25x thermal advantage over the 80 W/(m·K) SiC used in the study. This minimizes T_w and maximizes $\eta$.
Large-Area Heat Sinks (Scaling up the 20mm x 20mm model)	High-Purity Polycrystalline Diamond (PCD)	We supply PCD plates/wafers up to 125mm in diameter, enabling the fabrication of large-scale, high-flux microchannel heat sinks for industrial applications.
Microchannel Fabrication (Wavy, Fin, and Complex Geometries)	Custom Dimensions & Thickness	We provide SCD and PCD plates with thicknesses ranging from 0.1µm to 500µm, and substrates up to 10mm. Our materials are compatible with advanced micro-machining techniques (e.g., laser cutting, RIE) required to replicate the optimized diamond fin structures.
Optimal Solid-Fluid Interface (Minimizing friction drag)	Precision Polishing Services	SCD material is polished to an ultra-smooth finish (Ra < 1nm), and inch-size PCD to Ra < 5nm. This superior surface quality is critical for minimizing friction entropy generation and pressure drop ($\Delta p$) in laminar flow regimes.
Integration with Liquid Metal Coolants (Li, GaIn, etc.)	Custom Metalization	We offer in-house metalization (Au, Pt, Pd, Ti, W, Cu) for creating robust, chemically inert interfaces necessary for reliable bonding and integration into high-temperature liquid metal cooling loops.
Design Optimization Support (Fin size/height ratios)	In-House Engineering Support	6CCVD’s PhD-level team specializes in diamond thermal management and can assist engineers in selecting the optimal diamond grade and dimensions for replicating or extending this high-temperature liquid metal microchannel research.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).

View Original Abstract

The microchannel heat sink has been recognized as an excellent solution in high-density heat flux devices for its high efficiency in heat removal with limited spaces; however, the most effective structure of microchannels for heat dissipation is still unknown. In this study, the fluid flow and heat transfer in high-temperature wavy microchannels with various shaped fins, including the bare wavy channel, and the wavy channel with circular, square, and diamond-shaped fins, are numerically investigated. The liquid metal-cooled characteristics of the proposed microchannels are compared with that of the smooth straight channel, with respect to the pressure drop, average Nusselt number, and overall performance factor. The results indicate that the wavy structure and fin shape have a significant effect on the heat sink performance. Heat transfer augmentation is observed in the wavy channels, especially coupled with different shaped fins; however, a large penalty of pressure drops is also found in these channels. The diamond-shaped fins yield the best heat transfer augmentation but the worst pumping performance, followed by the square-, and circular-shaped fins. When the Re number increases from 117 to 410, the Nu number increases by 61.7% for the diamond fins, while the ∆p increases as much as 7.5 times.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi14071366

References

2004 - Cooling of high-power-density microdevices using liquid metal coolants [Crossref]
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2022 - Embedded microfluidic cooling with compact double H type manifold microchannels for large-area high-power chips [Crossref]
2023 - Porous-fin microchannel heat sinks for future micro-electronics cooling [Crossref]
1981 - High-performance heat sinking for VLSI [Crossref]
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2006 - Thermal characteristics of tree-shaped microchannel nets for cooling of a rectangular heat sink [Crossref]
2012 - Analysis of heat transfer characteristics of double-layered microchannel heat sink [Crossref]
2020 - Effect of a micro heat sink geometric design on thermo-hydraulic performance: A review [Crossref]
2021 - A holistic approach to thermal-hydraulic design of 3D manifold microchannel heat sinks for energy-efficient cooling [Crossref]