Effect of the addition of pie-shaped ribs and parallelogram ribs in micro-channels on thermal performance using diamond-water nanofluid
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-02-12 |
| Journal | SN Applied Sciences |
| Authors | Kamel Chadi, Nourredine Belghar, Belhi Guerira, Mohammed Lachi, Mourad Chikhi |
| Institutions | University of Biskra |
| Citations | 2 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond Micro-Channel Heat Sinks
Section titled âTechnical Documentation & Analysis: Diamond Micro-Channel Heat SinksâExecutive Summary
Section titled âExecutive SummaryâThis documentation analyzes research concerning the optimization of micro-channel heat sinks (MCHS) for high-power electronic cooling, specifically leveraging diamond-water nanofluids. The findings directly validate the necessity of high-thermal conductivity materials, aligning perfectly with 6CCVDâs core offerings.
- Application Focus: High-power density electronic cooling, requiring dissipation of extreme heat flux ($100 \text{ W/cm}^2$).
- Material Validation: The study confirms the superior thermal performance achieved by incorporating diamond (nanoparticles) into the coolant fluid.
- Geometric Optimization: Micro-channels featuring parallelogram ribs (Case 4) yielded the best results, achieving the highest Nusselt number (Nu) and lowest thermal resistance ($R_{th}$).
- Performance Gain: Maximum substrate temperature was reduced significantly, dropping from 333.24 K (plain channel) to 317.91 K (parallelogram ribs) at Re=200.
- 6CCVD Value Proposition: While the study used a low-conductivity silicon substrate, 6CCVD offers high-thermal conductivity MPCVD Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) substrates.
- Next-Generation Cooling: Utilizing 6CCVDâs diamond substrates instead of silicon enables a massive leap in thermal management capability, allowing for direct integration of diamond into the heat path for maximum efficiency.
- Custom Fabrication: 6CCVD provides the necessary custom dimensions, precision laser cutting, and metalization required to fabricate optimized diamond MCHS structures.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the numerical simulation of the micro-channel heat sinks (MCHS) using diamond-water nanofluid.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Applied Heat Flux (Q) | 100 | W/cm2 | Constant flux applied to the bottom wall. |
| Nanofluid Concentration ($\phi$) | 5 | % | Volume concentration of diamond nanoparticles. |
| Diamond Thermal Conductivity ($k_s$) | 2300 | W/m K | Nanoparticle property (Table 1). |
| Base Fluid Thermal Conductivity ($k_f$) | 0.613 | W/m K | Water at T=300 K. |
| Reynolds Number (Re) Range | 200 to 600 | - | Laminar flow regime studied. |
| Substrate Material Used in Study | Silicon | - | Material used for MCHS fabrication. |
| Micro-Channel Length (L) | 10 | mm | Total length of the heat sink. |
| Micro-Channel Height (H) | 0.35 | mm | Total channel height. |
| Lowest Thermal Resistance ($R_{th}$) | $\approx 0.25$ | K/W | Achieved by Case 4 (parallelogram ribs) at Re=600. |
| Highest Nusselt Number (Nu) | $\approx 16$ | - | Achieved by Case 4 (parallelogram ribs) at Re=600. |
| Maximum Temperature (Case 1, Re=200) | 333.24 | K | Highest temperature observed (plain channel). |
| Maximum Temperature (Case 4, Re=200) | 317.91 | K | Lowest temperature observed (parallelogram ribs). |
Key Methodologies
Section titled âKey MethodologiesâThe numerical simulation utilized Ansys Fluent to model the thermal and hydraulic performance of four micro-channel geometries.
- Modeling Environment: 3D numerical simulation using Ansys Fluent software, based on the Finite Volume Method (FVM).
- Flow Assumptions: Stationary, Newtonian, incompressible, and laminar flow (Re 200-600).
- Coolant: Diamond-water nanofluid with a 5% volume concentration of diamond nanoparticles.
- Geometric Variations: Four silicon MCHS cases were studied:
- Case 1: Plain rectangular micro-channel (no ribs).
- Case 2: Wavy sidewalls (2/3L length).
- Case 3: Wavy sidewalls + Pie-shaped ribs.
- Case 4: Wavy sidewalls + Parallelogram ribs (Optimal performance).
- Thermal Boundary Conditions: Constant heat flux of $100 \text{ W/cm}^2$ applied to the bottom wall (simulating electronic component heat). All other outside faces were assumed adiabatic.
- Inlet Conditions: Constant velocity ($w_{inlet}$) and constant temperature ($T_{inlet} = 300 \text{ K}$).
- Solution Algorithm: SIMPLE algorithm was used for pressure-velocity coupling; governing equations were solved using a second-order upwind scheme for energy.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research demonstrates that even a small volume fraction of diamond nanoparticles significantly enhances heat transfer in micro-channels. However, the use of a low-conductivity silicon substrate limits the overall thermal performance. 6CCVD specializes in providing high-purity, high-thermal conductivity MPCVD diamond materials that can replace silicon, enabling superior thermal management solutions for extreme heat fluxes ($100 \text{ W/cm}^2$ and beyond).
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and significantly extend this research, 6CCVD recommends the following materials:
| Material Grade | Description | Application Relevance |
|---|---|---|
| High Thermal Conductivity SCD | Single Crystal Diamond (SCD) with thermal conductivity up to 2000 W/m K. | Ideal for the substrate material, eliminating the thermal bottleneck caused by silicon and maximizing heat spreading efficiency beneath the micro-channels. |
| Optical Grade SCD | High-purity SCD suitable for applications requiring optical access or extremely smooth internal channel walls (Ra < 1 nm). | Recommended for micro-fluidic systems where surface roughness must be minimized to control friction factor (f) while maximizing Nu. |
| High Thermal Conductivity PCD | Polycrystalline Diamond (PCD) plates up to 125 mm in diameter, offering high thermal conductivity (typically 1000-1800 W/m K). | Best choice for scaling up MCHS designs to inch-size wafers, providing a cost-effective, high-performance platform for large electronic arrays. |
Customization Potential
Section titled âCustomization PotentialâThe complex geometries studied (wavy walls, parallelogram ribs) require high-precision fabrication, which 6CCVD provides in-house.
- Custom Dimensions: While the study used a 10 mm x 5 mm area, 6CCVD can supply PCD plates up to 125 mm in diameter and SCD/PCD substrates up to 10 mm thick, allowing for scaling of MCHS designs.
- Precision Micro-Machining: We offer advanced laser cutting and etching services to define complex micro-channel geometries, ensuring the precise rib shapes (parallelogram, pie-shaped) and dimensions (e.g., $W_r = 0.05 \text{ mm}$) necessary for optimal flow dynamics.
- Ultra-Low Roughness Polishing: To mitigate the friction factor penalty observed in ribbed channels (Case 4 had the highest friction factor), 6CCVD provides SCD polishing to Ra < 1 nm and PCD polishing to Ra < 5 nm for inch-size wafers, ensuring minimal hydraulic resistance.
- Metalization for Integration: For reliable fluidic manifold bonding and electronic component attachment, 6CCVD offers internal metalization capabilities, including Ti/Pt/Au, W, Cu, and Pd stacks, ensuring robust, hermetic seals compatible with high-pressure nanofluid systems.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD engineering team specializes in diamond thermal management solutions. We can assist researchers and engineers in:
- Material Selection: Determining the optimal diamond grade (SCD vs. PCD) based on required thermal conductivity, size, and cost constraints for specific high-power density projects.
- Design Transition: Consulting on the transition from low-conductivity substrates (like silicon) to all-diamond MCHS designs, helping to model and optimize geometric parameters (rib height, attack angle, position) for maximum thermal efficiency.
- Interface Optimization: Providing expertise on metalization and bonding techniques to ensure minimal thermal contact resistance between the diamond heat sink and the electronic device.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract In this paper, we numerically study the influence of the addition of parallelogram ribs and pie-shaped ribs in micro-channels on thermal exchange in three dimensions. We design four different silicon micro-channel heat sinks; the first and second cases without ribs, the third case with added pie-shaped ribs, and a fourth case containing parallelogram ribs. The main purpose of this research is to determine the best micro-channel heat sink in which the heat dissipation is sufficient to improve the heat exchange performance of the micro-channel, as well as to improve the cooling of the electronic components. A constant heat flux is applied to the bottom wall of the four micro-channels, and we use liquid diamond-water with a volume concentration of 5% diamond nanoparticles as a coolant, with a Reynolds number chosen between 200 and 600. The numerical results show that the Nusselt number (Nu) of the micro-channel that contains the parallelogram ribs is higher than that for the other cases, and it also yiels lower temperature values on the bottom wall of the substrate compared to the micro-channel containing pie ribs. When increasing the flow velocity, the thermal resistance of the micro-channel decreases in all cases, and we then find the largest value of the friction factor in the fourth case (with parallelogram ribs).
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2016 - Electronics cooling