Surface-modified component and method of achieving high heat transfer during cooling
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Solution Overview
Problem
Current methods for enhancing flow boiling heat transfer in industrial applications are difficult to scale, lack durability, and are often limited to specific fluids and materials, making it challenging to achieve high heat transfer coefficients in conventional millimetric-scale channels.
Innovation Solution
A scalable surface modification technique using hydrochloric acid etching to create microscale roughness features and microcavities on aluminum surfaces, which enhances nucleation site density and heat transfer during flow boiling, without the need for specialized equipment or additional coatings, thereby increasing the average heat transfer coefficient to at least 10 kW/(m2·K) at a mass flux of 300 kg/(m2·s.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If surface macro, micro, and nanostructuring techniques are used to enhance heat transfer coefficient, then heat transfer efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the surface parameters of the heat exchanger by creating microscale roughness features (1-15 microns height) and microcavities (2-30 microns linear size) through chemical etching. This transforms the smooth surface into a structured surface with controlled geometric parameters that enhance nucleation site density and heat transfer coefficient to at least 10 kW/(m2·K).
Solution Approach 2:
The patent creates a porous-like surface structure with microcavities and roughness features on the heat exchanger surface. These microstructural features act as nucleation sites for bubble formation during flow boiling, significantly enhancing heat transfer efficiency while maintaining a relatively simple overall device structure.
2Power
If multiple small-diameter channels are used to maintain reasonable pressure drops, then heat transfer is improved, but flow maldistribution and manufacturing complexity increase
Solution Approach 1:
The patent applies local quality modification by creating microscale roughness features and microcavities specifically on the inner surface of conventional millimetric-scale channels. This local surface structuring enhances heat transfer at the wall-fluid interface without changing the overall channel geometry or requiring flow splitting into multiple small channels.
3Device complexity
If conventional millimetric-scale channels are used, then device simplicity is maintained, but heat transfer coefficient is limited
Solution Approach 1:
The patent changes the surface parameters of conventional millimetric-scale channels by introducing microscale roughness (1-15 microns) and microcavities (2-30 microns). This surface parameter modification enables heat transfer coefficients of at least 10 kW/(m2·K) while maintaining the simplicity of conventional channel geometries and avoiding the need for complex microchannel networks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The technique achieves significant heat transfer enhancements with minimal pressure drop penalty, demonstrating durability over 28 days and potential for longer-term stability, making it suitable for various industrial applications including refrigeration, HVAC, and power generation.
Implementation Method 1
exposing the inner surface to a hydrochloric acid (HCl) solution comprising a HCl concentration of 2 M to 5 M
Implementation Method 2
During the transport, the refrigerant absorbs heat from a thermal load and undergoes flow boiling
Implementation Method 3
The inner surface comprises microscale roughness features and microcavities configured to enhance nucleation site density during flow boiling
Data Source
AI summary
A method of achieving high heat transfer during cooling includes providing an aluminum body having an inner surface enclosing a channel, where the inner surface comprises microscale roughness features and microcavities configured to enhance nucleation site density during flow boiling. A refrigerant is transported through the channel. During the transport, the refrigerant absorbs heat from a thermal load and undergoes flow boiling. The heat is transferred to the refrigerant at an average heat transfer coefficient of at least about 10 kW/(m2·K) at a mass flux of about 300 kg/(m2·s).