Microchannel Heat Pipe Design for Passive Microelectronics Cooling
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Solution Overview
Problem
Conventional heat pipes have limitations in heat transfer rates due to the mechanical complexity and energy intensity of secondary cooling systems, and the heat transfer capacity is often restricted by the design of heat absorbers and sinks, particularly when the ratio of fluid internal surface area to working fluid volume is small.
Innovation Solution
The use of microchannel heat exchangers as heat absorbers and sinks in heat pipes, with cross-sectional dimensions less than 1000 microns, and a passive system that employs a liquid working fluid to absorb heat, form vapor, and condense it outside the enclosure, allowing for simultaneous flow of vapor and liquid back to the absorber, enhancing heat transfer rates without mechanical moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional heat pipes with simple heat exchangers are used, then the device complexity is low, but the heat transfer rate is limited due to small fluid internal surface area to working fluid volume ratio
Solution Approach 1:
The heat exchanger is segmented into multiple microchannels (with cross-sectional dimensions less than 1000 microns) instead of using a single large channel. This segmentation increases the fluid internal surface area to working fluid volume ratio, thereby enhancing heat transfer rate without requiring complex external cooling systems.
Solution Approach 2:
The invention transitions from conventional macro-scale heat exchanger geometry to micro-scale geometry by reducing cross-sectional dimensions to less than 1000 microns. This dimensional change dramatically increases the surface area to volume ratio, enabling high heat transfer rates while maintaining a compact and relatively simple device structure.
2Productivity
If secondary cooling systems (air conditioning or pumped liquid systems) are used to remove heat from the enclosure, then the heat dissipation capacity is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The heat pipe system is designed to be self-contained and passive, using the phase change of working fluid (evaporation at the heat absorber and condensation at the heat sink) to drive heat transfer. The system eliminates the need for external powered cooling devices such as air conditioners or pumped liquid systems, thereby reducing device complexity and energy consumption while maintaining high heat dissipation capacity.
Solution Approach 2:
The invention replaces mechanically complex and energy-intensive secondary cooling systems with a passive heat pipe system that relies on thermodynamic phase change and natural convection. This substitution eliminates moving parts and external power requirements, significantly simplifying the cooling system architecture.
3Productivity
If conventional heat exchanger designs are used, then the manufacturing is simpler, but the heat transfer capacity is restricted by the heat transfer surface area
Solution Approach 1:
The heat exchanger is divided into multiple microchannels with cross-sectional dimensions less than 1000 microns. This segmentation increases the effective heat transfer surface area within a compact volume, enhancing heat transfer capacity while using standard manufacturing techniques for creating microchannel structures.
Solution Approach 2:
The invention changes the geometric parameters of the heat exchanger by reducing cross-sectional dimensions to the micro-scale (less than 1000 microns). This parameter change fundamentally increases the surface area to volume ratio, enabling high heat transfer capacity. The microchannel geometry can be manufactured using established techniques such as etching, extrusion, or additive manufacturing.
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
This configuration significantly enhances heat transfer rates by reducing thermal and convective resistance, allowing for efficient heat dissipation from electronic devices without the need for energy-consuming cooling systems, thereby reducing the need for air-conditioning in rooms housing these devices.
Implementation Method 1
the microchannels are adapted to contain a liquid working fluid that absorbs heat from the microelectronic device and forms a vapor upon flowing therethrough
Implementation Method 2
a heat sink located outside of the enclosure for receiving and condensing the vapor to reform the liquid working fluid
Implementation Method 3
The condensed fluid returns to the hot end by gravity or capillary action via a wick
Data Source
AI summary
In one general aspect, a microelectronics cooling device can include a microchannel heat exchanger within an enclosure that houses the device at a heat absorbing end and another heat exchanger which is optionally also a microchannel heat exchanger at a heat sink end outside the enclosure. One or more pipes flowably connect the two ends for transporting liquid working fluid to the heat absorber and vaporized working fluid to the heat sink. The heat pipes may also be used to transfer heat outside a room that contains the electronic devices.