Active Two-Phase Cooling Control for Dry-Out Prevention
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Solution Overview
Problem
Two-phase liquid cooling systems face challenges such as dry-out under heavy computational loads, leading to increased thermal resistance and processor temperature, which existing cooling methods fail to effectively manage.
Innovation Solution
An active two-phase cooling system with a cooling device that includes cavities with active coolant flow control, a reservoir for phase transition, and a capacitance sensor to adjust coolant flow based on vapor quality and void fraction, ensuring continuous coolant flow and minimizing thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If two-phase liquid cooling systems are used to reduce thermal resistance, then cooling efficiency is improved, but the system may dry out under heavy computational loads
Solution Approach 1:
The patent employs capacitance sensors to continuously monitor the void fraction and vapor quality of the two-phase coolant in real-time. This feedback information is fed to a controller that dynamically adjusts coolant flow rates and pump operations to prevent dry-out conditions while maintaining optimal cooling efficiency under varying computational loads
Solution Approach 2:
The system transitions from static cooling configurations to dynamic control mechanisms that adapt coolant flow rates, pump speeds, and even channel configurations based on real-time thermal conditions and computational workload, enabling the system to optimize between cooling performance and dry-out prevention
2Temperature
If small cavity channels are used to increase heat transfer surface area, then heat transfer efficiency is improved, but the system becomes more susceptible to dry-out
Solution Approach 1:
The patent implements different channel geometries, sizes, and configurations in different regions of the cooling device. High-heat-flux areas receive channels optimized for maximum heat transfer, while other regions have channels designed to maintain liquid presence and prevent dry-out, creating locally optimized cooling zones
Solution Approach 2:
The cooling system is divided into multiple independent channels or zones that can be individually controlled and monitored. This segmentation allows differential coolant distribution strategies to be applied to different regions, preventing system-wide dry-out while maintaining high heat transfer efficiency in critical areas
3Reliability
If active coolant flow control is implemented to prevent dry-out, then system reliability is improved, but device complexity increases
Solution Approach 1:
The system incorporates self-regulating mechanisms where capacitance sensors automatically detect void fraction changes and trigger proportional responses in coolant flow control, reducing the need for complex external control systems and enabling the cooling device to self-adjust to varying thermal conditions
Solution Approach 2:
The patent utilizes changes in electrical parameters (capacitance, dielectric constant) of the two-phase coolant to infer thermal state and void fraction, converting thermal monitoring into electrical measurement domain which simplifies sensing and control architecture compared to direct thermal measurement approaches
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 system reduces thermal resistance by up to 20 times compared to air-cooled servers, minimizing processor power consumption and enabling efficient year-round data center cooling, with dynamic control optimizing cooling power at the chip module level.
Implementation Method 1
a capacitance sensor configured to determine a coolant capacitance in the cavities
Implementation Method 2
a two-phase coolant in the reservoir and cavities, wherein the two-phase coolant has a phase transition temperature between an ambient temperature and an expected device temperature
Implementation Method 3
The heat spreader is attached to an air heat sink through a second TIM layer, and the heat sink conducts heat to the room ambient environment
Implementation Method 4
two-phase liquid cooling systems
Data Source
AI summary
A cooling system includes a device to be cooled and a cooling device integrated with the device to be cooled. A cooling volume has cavities and active coolant flow controls configured to adjust coolant flow through the cavities. A reservoir is in fluid communication with the cavities and has a liquid outlet and an inlet for a gas or gas-liquid mixture. A two-phase coolant is in the reservoir and cavities. The two-phase coolant has a phase transition temperature between an ambient temperature and an expected device temperature. A capacitance sensor is configured to determine a coolant capacitance in the cavities. A control module is configured to determine a vapor quality and void fraction of the coolant based on the measured capacitance and to increase coolant flow if the determined vapor quality and void fraction indicate a dry-out condition. A secondary cooling line removes heat from the cooling device.