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6CCVD Research

Enhancement Effect of a Diamond Network on the Flow Boiling Heat Transfer Characteristics of a Diamond/Cu Heat Sink

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2023-10-24
JournalEnergies
AuthorsNan Wu, M. Sun, Guo Hong, Zhongnan Xie, Shijie Du
InstitutionsState Key Laboratory of Nonferrous Metals and Processes, General Research Institute for Nonferrous Metals (China)
Citations11
AnalysisFull AI Review Included

Enhancement Effect of a Diamond Network on the Flow Boiling Heat Transfer Characteristics of a Diamond/Cu Heat Sink

Section titled “Enhancement Effect of a Diamond Network on the Flow Boiling Heat Transfer Characteristics of a Diamond/Cu Heat Sink”

Executive Summary

Section titled “Executive Summary”

This study successfully demonstrated the superior flow boiling heat transfer performance of a diamond/Cu composite micro heat sink compared to a traditional pure copper heat sink, leveraging a specialized internal heat conduction network.

  • Performance Gain: The diamond/Cu heat sink achieved a 38-51% increase in the heat transfer coefficient (h) and a significant reduction in wall superheat (ΔTsat) by 10.2-14.5 °C under identical heat fluxes.
  • Thermal Uniformity: The composite material exhibited vastly improved thermal stability. At high heat flux (1600 kW/m2), the temperature difference (ΔT) across the sink bottom was 29% lower, and the temperature fluctuation amplitude (σ) was reduced by 39%.
  • Material Innovation: A three-dimensional heat conduction network was constructed using bimodal diamond particles (400 ”m main, 30-40 ”m secondary) within a Cu-Cr matrix, ensuring high thermal conductivity (780 W/mK).
  • Boiling Mechanism: The diamond network enhances boiling intensity by increasing the internal heat flux to the surface and creating a much higher density of active nucleation sites compared to the pure Cu surface.
  • Interface Control: A continuous Cr3C2 interface layer (approx. 610 nm thick) was formed, providing excellent bonding and low thermal resistance, crucial for efficient phonon transport between diamond and copper.
  • Modeling Validation: A refined heat transfer model combining Computational Fluid Dynamics (CFD) with a transient thermal analysis (incorporating Diffusion Mismatch Model (DMM) calculations for interfacial thermal conductivity) accurately simulated the enhanced performance.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Diamond/Cu Thermal Conductivity (λ)780W/(mK)Composite bulk property
Diamond/Cu CLTE4.0 x 10-6/KCoefficient of Linear Thermal Expansion
Diamond Volume Fraction60-65%In Diamond/Cu composite
Heat Transfer Coefficient (h) Enhancement38-51%Compared to pure Cu heat sink
Wall Superheat (ΔTsat) Reduction10.2-14.5°CCompared to pure Cu heat sink
Temperature Difference (ΔT) Reduction29%At 1600 kW/m2, compared to Cu
Temperature Fluctuation (σ) Reduction39%At 1600 kW/m2, compared to Cu
Specific Mass Flux (G)507kg/(m2s)Experimental flow condition
Inlet Subcooling (ΔTsub)20°CExperimental flow condition
Heat Sink Dimensions10 x 20 x 2mmSize of the fabricated heat sink
Cr3C2 Interface Layer Thickness610nmMeasured microstructure
Interfacial Thermal Conductivity (hIF) (Cu-Cr3C2)5.138 x 108W/(m2K)Calculated via DMM
Interfacial Thermal Conductivity (hIF) (Diamond-Cr3C2)4.820 x 109W/(m2K)Calculated via DMM

Key Methodologies

Section titled “Key Methodologies”
  1. Bimodal Diamond Network Construction: Main diamond particles (400 ”m) and secondary diamond particles (30-40 ”m) were uniformly mixed with a binder and vacuum dried at 450 °C for 60 min to pre-form the heat conduction network structure.
  2. Liquid Phase Infiltration: Cu-Cr alloy (1.0 wt% Cr) was heated to 1250 °C and poured into the mold containing the diamond network. A vertical pressure of 60 MPa was applied to force the alloy to infiltrate the network, ensuring high density and minimal porosity.
  3. Interface Layer Formation: During high-temperature preparation, the Cr element in the matrix reacted with C on the diamond surface, resulting in the in-situ growth of a continuous Cr3C2 interface layer (approximately 610 nm thick), confirmed by High-Resolution TEM.
  4. Flow Boiling Experimentation: Experiments were conducted in a closed-loop system using deionized water. The test section utilized K-type and T-type thermocouples for precise temperature monitoring (±0.30 °C uncertainty for T-type).
  5. Heat Flux Calculation: Unidirectional heat flux (q”) was calculated using Fourier’s law, estimating the temperature gradient (dT/dx) via a three-point backward Taylor series approximation based on thermocouple readings within the copper substrate.
  6. Interfacial Thermal Conductivity Modeling: The Diffusion Mismatch Model (DMM) was employed to calculate the thermal conductivity coefficients (hIF) across the complex interfaces (Cu-Cr3C2, Cr3C2-Diamond), accounting for phonon scattering.
  7. Refined Heat Transfer Model: A coupled simulation was performed using ANSYS Fluent 19.0 (Volume of Fluid model) combined with a transient thermal model. The model incorporated the DMM-calculated hIF values and the actual microstructure geometry to accurately predict the flow boiling performance.

Commercial Applications

Section titled “Commercial Applications”

The enhanced thermal performance and stability offered by the diamond/Cu composite heat sink make it highly suitable for applications requiring extreme heat dissipation and thermal management near sensitive components.

  • High-Performance Computing (HPC): Cooling solutions for high-power density CPUs, GPUs, and specialized AI accelerators in data centers, enabling sustained peak performance and preventing thermal throttling.
  • Semiconductor Packaging: Direct integration as a substrate or heat spreader in high-power chip packages (e.g., SiC and GaN power modules) due to the low and compatible Coefficient of Linear Thermal Expansion (CLTE).
  • Defense and Radar Systems: Thermal management for high-frequency, high-power radio frequency (RF) components and solid-state radar modules where localized heat flux is extremely high.
  • Electric Vehicle (EV) Power Electronics: Advanced cooling for traction inverters, DC-DC converters, and battery thermal management systems, improving the reliability and lifespan of critical power components.
  • Industrial Lasers and Optics: Heat dissipation for high-power laser diodes and optical components where precise temperature control is necessary to maintain beam quality and efficiency.
View Original Abstract

The use of a micro heat sink is an effective means of solving the problem of high-power chip heat dissipation. Diamond/Cu composites exhibit high thermal conductivity and a linear thermal expansion coefficient that is compatible with semiconductor materials, rendering them ideal micro heat sink materials. The aim of this study was to fabricate diamond/Cu and Cu separately as heat sinks and subject them to flow boiling heat transfer experiments. The results indicate that the diamond/Cu heat sink displayed a decrease in wall superheat of 10.2-14.5 °C and an improvement in heat transfer coefficient of 38-51% compared with the Cu heat sink under identical heat fluxes. The heat sink also exhibits enhanced thermal uniformity. Secondary diamond particles are incorporated into the gaps of the main diamonds, thereby constructing a three-dimensional heat conduction network within the composite material. The diamond network enhances the internal heat flux of the material while also creating more nucleation sites on the surface. These increase the boiling intensity of the diamond/Cu heat sink, leading to better heat transfer performance. By combining the transient thermal model with computational fluid dynamics, a heat transfer model based on the diamond/Cu heat sink is proposed. The efficient heat dissipation capability of diamond/Cu heat sinks can lower the working temperature of microelectronic devices, thereby improving device performance and reliability during operation.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2018 - Experimental observation of high thermal conductivity in boron arsenide [Crossref]
  2. 2017 - Heat transfer augmentation in a microchannel heat sink with sinusoidal cavities and rectangular ribs [Crossref]
  3. 2018 - Low-cost nanostructures from nanoparticle-assisted large-scale lithography significantly enhance thermal energy transport across solid interfaces [Crossref]
  4. 2011 - Investigation of thermal management materials for automotive electronic control units [Crossref]
  5. 2014 - Emerging challenges and materials for thermal management of electronics [Crossref]
  6. 2007 - Analytical solution for heat conduction problem in composite slab and its implementation in constructal solution for cooling of electronics [Crossref]
  7. 2022 - Hybrid nanofluid spray cooling performance and its residue surface effects: Toward thermal management of high heat flux devices [Crossref]
  8. 2022 - Structure optimization of a heat pipe-cooling battery thermal management system based on fuzzy grey relational analysis [Crossref]
  9. 2021 - Experimental study of flow boiling performance of open-ring pin fin microchannels [Crossref]
  10. 2008 - Thermal conductivity of Al-SiC composites with monomodal and bimodal particle size distribution [Crossref]

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