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

Executive Summary

This analysis focuses on the numerical investigation of a novel double-layer pin-fin Manifold Microchannel (MMC) heat sink designed for high-flux electronic cooling (100 W/cm²).

Core Value Proposition: The double-layer pin-fin MMC structure significantly improves comprehensive thermal performance by balancing enhanced heat transfer with a substantial reduction in pressure drop.
Pressure Drop & Uniformity: Compared to the single-layer MMC, the double-layer design achieved up to 35.2% lower pressure drop and demonstrated superior temperature uniformity (lower maximum temperature difference, ΔT).
Thermal Trade-off: The pressure drop reduction was achieved at the cost of a slightly higher thermal resistance, ranging from 2.1% to 5.7% compared to the single-layer structure.
Optimal Pin-Fin Shape: Round cross-section pin-fins provided the best overall comprehensive performance (factor ζ) and the minimal thermal resistance among the tested shapes (round, diamond, rectangular).
Sizing Constraint: Comprehensive performance increases with pin-fin size but sharply decreases when the diameter exceeds a critical threshold (approximately 1.1 mm) due to excessive pressure drop penalty.
Height Ratio Recommendation: For optimal flow and heat transfer, a larger height ratio (H₂/H₁) is recommended for low inlet velocities, while a smaller ratio is advised for high inlet velocities.

Technical Specifications

Parameter	Value	Unit	Context
Working Fluid	Deionized Water	N/A	Numerical Simulation Medium
Heat Flux (q)	100	W/cm²	Uniform heat source at bottom boundary
Inlet Temperature (T_in)	293.15	K	Standard operating condition
Inlet Pressure	0.1	MPa	Standard operating condition
Inlet Velocity Range (u)	1.2 to 3.6	m/s	Tested range
Microchannel Layer Height (H₁, H₂)	0.3	mm	Baseline height for comparison
Optimal Pin-Fin Shape	Round	N/A	Best comprehensive performance
Pin-Fin Diameter Range (d)	0.4 to 1.1	mm	Tested range for size optimization
Height Ratio Range (α = H₂/H₁)	0.4 to 1.2	N/A	Tested range for layer optimization
Pressure Drop Reduction (Max)	35.2	%	Double-layer vs. Single-layer MMC
Thermal Resistance Increase	2.1 to 5.7	%	Double-layer vs. Single-layer MMC
Simulation Software	ANSYS Fluent 2020R2	N/A	Numerical analysis tool

Key Methodologies

Simulation Environment: Numerical simulations were performed using ANSYS Fluent 2020R2, solving the continuity, momentum, and energy equations under steady-state, incompressible flow conditions.
Turbulence Modeling: The k-epsilon (k-ε) turbulence model was adopted due to the high local turbulence generated by the numerous pin-fins and the multi-inlet jet effects within the microchannels.
Meshing and Verification: Polyhedral meshes were generated to accurately capture complex geometric features. Grid independence was verified, setting the final mesh count at 594,758 elements, with five refined boundary layers near the walls.
Boundary Conditions: A uniform heat source of 100 W/cm² was applied to the bottom boundary. The working fluid (deionized water) entered at 293.15 K and 0.1 MPa via a velocity inlet and exited through a pressure outlet.
Validation: The simulation methodology was validated against published experimental data for a single-layer MMC structure (Drummond [29]), confirming reliability with a maximum deviation of less than 1% in average heat sink temperature.
Geometric Parameter Analysis: The study systematically varied three key geometric parameters to optimize performance:
- Pin-fin cross-section (Round, Diamond, Rectangle, maintaining equal circumscribed circle diameter).
- Pin-fin size (diameter ranging from 0.4 mm to 1.1 mm).
- Height ratio (α = H₂/H₁, ranging from 0.4 to 1.2).
Performance Evaluation: Performance was quantified using four metrics: Effective Thermal Resistance (R_eff), Maximum Temperature Difference (ΔT), Pressure Drop (ΔP), and the Comprehensive Performance Index (ζ).

Commercial Applications

The double-layer pin-fin MMC structure is highly relevant for thermal management in systems requiring high heat dissipation density and low pumping power overhead.

High-Performance Computing (HPC): Essential for cooling modern CPUs, GPUs, and specialized accelerators where heat fluxes routinely exceed 100 W/cm², enabling higher clock speeds and component density.
Power Electronics: Applicable in systems like inverters, converters, and solid-state relays where thermal runaway is a critical failure mode, benefiting from the improved temperature uniformity.
Micro-Electro-Mechanical Systems (MEMS): Provides a compact, high-efficiency cooling solution for integrated micro-devices and microfluidic systems.
Aerospace and Defense Systems: Used in compact electronic packages where weight and volume constraints demand highly efficient heat sinks with minimal flow resistance.
Laser Technology: Directly applicable to cooling high-power laser crystals and optical components, where stable, uniform temperature control is crucial for beam quality and longevity.

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

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