Evaporative Compact High Intensity Cooler for Thermal Management
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Solution Overview
Problem
High power electronic devices generate high heat fluxes that require efficient heat transfer and thermal management, especially in limited space applications, where existing cooling systems struggle to maintain constant temperature and minimize thermal resistance.
Innovation Solution
The Evaporative Compact High Intensity Cooler (ECHIC) employs a three-dimensional flow passage labyrinth with laminated structure and expanding flow areas to maintain nearly isobaric conditions and limit boundary layer formation, using a two-phase coolant for enhanced heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional heat sink is used for high power electronic devices, then the device can operate, but the temperature rises above acceptable ranges and surface isothermality deteriorates
Solution Approach 1:
The patent employs two-phase heat transfer where a working fluid undergoes phase change from liquid to vapor in the evaporator, absorbing large amounts of heat at constant temperature. This phase transition mechanism enables the heat sink to maintain temperatures within acceptable ranges even under high heat flux conditions, directly resolving the temperature control issue.
Solution Approach 2:
The heat sink is segmented into distinct functional zones: evaporator, condenser, and expansion device. The evaporator section specifically addresses the heat source interface with optimized flow passages that enhance surface isothermality, while other sections handle different stages of the refrigeration cycle, allowing each segment to be optimized for its specific function.
2Power
If thermal pumping is used to reject waste heat to a heat sink at higher temperature, then heat rejection is achieved, but the system complexity and energy consumption increase
Solution Approach 1:
The patent merges the heat rejection function into the same compact device housing as the heat absorption function. The evaporator and condenser are integrated within a single heat sink unit, eliminating the need for separate thermal pumping systems and reducing overall system complexity while maintaining effective heat rejection capability.
Solution Approach 2:
The two-phase refrigeration system within the heat sink operates autonomously, with the working fluid automatically circulating through evaporation, condensation, and expansion cycles. This self-service mechanism eliminates the need for external thermal pumping equipment, reducing system complexity and energy consumption.
3Productivity
If the evaporator absorbs heat at lower temperature, then heat absorption efficiency improves, but the pressure level control and temperature stability become more challenging
Solution Approach 1:
The working fluid undergoes phase change from liquid to vapor in the evaporator, which occurs at constant saturation temperature for a given pressure. This phase transition property inherently stabilizes the evaporator temperature, eliminating temperature fluctuations even under varying heat absorption conditions, while maintaining high heat absorption efficiency through the large latent heat of vaporization.
4Loss of energy
If the coolant changes temperature with heat addition, then heat transfer occurs, but the surface isothermality deteriorates compared to two-phase systems
Solution Approach 1:
The patent utilizes two-phase heat transfer where the working fluid maintains constant saturation temperature during evaporation. This constant temperature phase change process ensures uniform heat distribution across the heat source surface, maintaining excellent surface isothermality while achieving efficient heat transfer through the large latent heat of vaporization.
5Stress or pressure
If the flow area expands to accommodate vapor volume increase, then pressure losses are reduced, but maintaining shear control and annular flow becomes more difficult
Solution Approach 1:
The patent employs dynamic flow passage design where the cross-sectional area of the flow channels progressively increases along the flow direction. This dynamic expansion accommodates the large volume increase during vaporization while maintaining appropriate flow velocities. The varying geometry ensures that shear control and annular flow patterns are preserved throughout the evaporator, balancing pressure loss reduction with flow regime stability.
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 ECHIC achieves superior heat transfer by maintaining constant coolant temperature, reducing thermal resistance, and improving heat transfer coefficients, making it suitable for high heat flux applications with minimal boundary layer development.
Implementation Method 1
the coolant evaporates due to absorbing heat within the flow passages from the heat conduction surface
Implementation Method 2
a two-phase coolant for enhanced heat transfer
Implementation Method 3
transferred heat from a heat source along a heat conduction surface of the heat source
Implementation Method 4
Vapour specific volumes are in the range of 140 to 1000 times larger than their liquids. To manage flow velocities and thereby pressure losses during the large changes in volumetric flow a flow structure with and expanding flow area is required
Data Source
AI summary
An evaporative compact high intensity cooler (ECHIC) for transferring heat from a heat source along a heat conduction surface of the heat source with a two-phase coolant, comprises a flow passage labyrinth of flow passages with short conduction paths interrupted by coolant columns that all radiate from at least one coolant supply passage and offer the coolant expanding volume as the coolant evaporates due to absorbing heat within the flow passages from the heat conduction surface to maintain nearly isobaric conditions for the coolant to maintain relatively constant temperature throughout the ECHIC as it absorbs heat from the heat source and limit boundary layer formation within the flow passages to improve heat transfer.