Numerical Study of the Temperature Effects on Heat Transfer Coefficient in Mini-Channel Pin-Fin Heat Sink
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-02-28 |
| Journal | International Journal of Heat and Technology |
| Authors | Nabil Bessanane, Mohamed SiâAmeur, Mourad Rebay |
| Institutions | Université de Reims Champagne-Ardenne, University of Batna 1 |
| Citations | 12 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High Heat Flux Mini-Channel Heat Sinks
Section titled âTechnical Documentation & Analysis: High Heat Flux Mini-Channel Heat SinksâExecutive Summary
Section titled âExecutive SummaryâThis documentation analyzes the numerical study of heat transfer in mini-channel Pin-Fin Heat Sinks (PFHS) designed for extreme heat dissipation, such as cooling Synchrotron components. The findings validate the use of complex diamond-shaped pin-fin geometries for superior thermal management, directly aligning with 6CCVDâs expertise in high-performance diamond materials.
- Application Focus: Thermal management for high-power density devices, specifically addressing heat fluxes up to 500 W/cm2 peak.
- Performance Validation: Diamond-shaped PFHS configurations demonstrated superior thermal performance and heat transfer coefficients compared to standard Rectangular Mini-Channels (RMC).
- Critical Methodology: The study validated a Variable Reference Temperature (VRT) approach, essential for accurately calculating the convective heat transfer coefficient (HTC) in complex, small-scale, conjugated heat transfer systems.
- Achieved HTC: Local heat transfer coefficients reached up to 40,000 W/m2K, confirming the effectiveness of the staggered pin-fin array in promoting turbulence and mixing.
- Material Opportunity: The research highlights the necessity of high thermal conductivity materials; 6CCVDâs MPCVD diamond offers thermal conductivity significantly exceeding conventional materials (e.g., copper), enabling replication and extension of these results to higher power densities.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the numerical study, focusing on the PFHS configuration and boundary conditions:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Applied Heat Flux (q) | 100 | kW/m2 | Constant flux imposed on the solid base |
| Peak Power Dissipation (Context) | Up to 500 | W/cm2 | Maximum required dissipation for application |
| Heat Sink Length (L) | 100 | mm | Overall dissipater dimension |
| Heat Sink Width (W) | 16 | mm | Overall dissipater dimension |
| Heat Sink Height (H) | 1.6 | mm | Channel height |
| Pin Fin Edge Dimension (C) | 1.7 | mm | Square base dimension of diamond pins |
| Fluid Passage Spacing (e) | 0.35 to 1.6 | mm | Varied geometric parameter |
| Inlet Temperature (Tin) | 303 | K | Fixed fluid inlet condition |
| Maximum Local HTC (h) | ~40,000 | W/m2K | Observed in PFHS configuration (Figure 10) |
| Mass Flow Rate (m) Range | 0.05 to 3 | kg/mn | Simulation range |
| Outlet Pressure | 3 | bars | Nominal experimental parameter |
| Hydraulic Diameter (Dh) Range | 10 to 1000 | ”m | General micro-channel classification |
Key Methodologies
Section titled âKey MethodologiesâThe numerical procedure utilized advanced computational fluid dynamics (CFD) to accurately model the complex thermal-fluid interactions within the mini-channels.
- Modeling Software: Numerical calculations were performed using ANSYS FLUENT, employing the Finite Volume Method.
- Turbulence Model: The Realizable k-Δ turbulence model was selected, coupled with âEnhanced-Wall-Treatment.â This is critical for accurately resolving velocity and temperature gradients near the walls, especially given the very reduced fluid passage dimensions (down to 0.35 mm).
- Heat Transfer Regime: Conjugate conduction-convection heat transfer was considered at the solid-fluid interface, accounting for heat conduction within the solid pin-fins and base plate.
- Boundary Conditions:
- Inlet: Fixed temperature (303 K) and velocity (derived from mass flow rate).
- Base: Uniform heat flux (q = 100 kW/m2) applied to the solid bottom.
- Walls: Non-slip condition applied to all internal walls; adiabatic condition applied to outside walls.
- Reference Temperature Approach (VRT): A Variable Reference Temperature (VRT) approach was adopted for calculating the heat transfer coefficient. This method uses the local average fluid temperature in the middle of the channel (Tref = Tave(x)), which was shown to provide a more physically accurate and stable HTC profile compared to fixed inlet/outlet averages.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research demonstrates the need for materials that can handle extreme heat flux (up to 500 W/cm2) while maintaining structural integrity and allowing for complex micro-machining. 6CCVDâs MPCVD diamond is the definitive solution for replicating and significantly enhancing the performance of these mini-channel heat sinks.
Applicable Materials
Section titled âApplicable MaterialsâThe paper notes that high thermal conductivity materials, such as copper, are typically used. However, for the high-power density applications described (Synchrotron cooling), diamond offers a performance advantage unmatched by any metal.
| 6CCVD Material Recommendation | Thermal Conductivity (W/mK) | Application Fit |
|---|---|---|
| Optical Grade Single Crystal Diamond (SCD) | > 2000 | Ultimate performance for critical components (e.g., X-ray mirrors, beam absorbers). Provides maximum heat spreading and lowest thermal resistance. |
| High Thermal Grade Polycrystalline Diamond (PCD) | 1000 - 2000 | Cost-effective solution for large-area heat sinks (up to 125 mm). Excellent thermal performance suitable for high-flux electronics and power devices. |
| Boron-Doped Diamond (BDD) | N/A (Semiconducting) | If the application requires integrated thermal management with electrochemical or sensing capabilities (e.g., integrated temperature sensors within the heat sink structure). |
Customization Potential
Section titled âCustomization PotentialâThe PFHS design requires precise manufacturing of complex geometries (diamond-shaped pins, staggered arrays) within a compact volume (100 mm x 16 mm x 1.6 mm). 6CCVDâs advanced processing capabilities ensure exact replication and optimization of these structures in diamond.
- Custom Dimensions: 6CCVD supplies diamond plates and wafers up to 125 mm in diameter (PCD), easily accommodating the required 100 mm length.
- Micro-Machining: We offer high-precision laser cutting and etching services to create the complex diamond pin-fin arrays and mini-channels with the required fluid passage spacing (e = 0.35 mm to 1.6 mm).
- Surface Finish: For optimal fluid dynamics and minimal pressure drop, 6CCVD provides polishing services achieving surface roughness of Ra < 1 nm (SCD) and Ra < 5 nm (Inch-size PCD).
- Metalization: If the heat sink requires integration into a larger system (e.g., bonding to a copper cold plate or sensor array), 6CCVD offers in-house metalization services including Ti/Pt/Au, W, Cu, and Pd layers.
Engineering Support
Section titled âEngineering SupportâThe success of this research hinges on complex thermal-fluid modeling (VRT approach, Realizable k-Δ). 6CCVDâs in-house PhD team specializes in integrating diamond materials into advanced thermal systems.
- Thermal Modeling Assistance: Our experts can assist engineers and scientists in selecting the optimal diamond grade and thickness (SCD: 0.1 ”m to 500 ”m) to achieve target temperature differences (ÎT) for similar Synchrotron Component Cooling projects.
- Design Optimization: We provide consultation on how diamondâs superior thermal properties can be leveraged to reduce the overall size and mass of the PFHS structure while maintaining or exceeding the required heat transfer coefficient (h).
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Pin-fins are frequently used to increase the heat transfer surface and promote turbulent motion, which improves the devices cooling process by enhancing heat dissipation, as in hydrogen fuel cells applications. The application has burst out this last decade and became vital in several industrial devices. The present study is a numerical investigation of flow and heat transfer in rectangular mini-channels (RMC) and pin-fin heatsinks (PFHS). The pin-fins have a diamond shape arranged in segregated disposition (corrugated channel). In order to adequately calculate the heat transfer coefficient within this complex thermal system; several parameters, such as mass flow rate, geometry dimensions, heat flux and reference temperature are extensively examined. The importance in way the reference temperature was calculated was highlighted. A correct estimation of the heat transfer coefficient led to a better optimisation of the cooling process performances. The aim of this study was to elaborate a technique to correctly estimate the temperature difference between the cooler fluid and the heat sink wall, leading to a better approach for heat transfer coefficient estimation. For this purpose, an approach with variable reference temperature (VRT) has been adopted in the calculation of the wall-fluid temperature difference. Flow field and heat transfer are analysed qualitatively (visualisations of sensible zones) and quantitatively (profiles of heat transfer coefficient, heat flux, wall and fluid temperaturesâŠ). The numerical procedure has been validated by experimental measurements. The results showed that the proposed approach to calculate the reference temperature leads to a better presentation of the heat transfer coefficient. In addition, new fit function was involved, in particular the variation of the averaged heat transfer coefficient against Reynolds number.