Two-Phase Cooling Circuits for Multi-Temperature Power Equipment
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Solution Overview
Problem
Existing cooling systems for electrical and mechanical systems, such as transformers and power semiconductor devices, face challenges in efficiently managing heat loads and operating temperatures, often requiring more space, energy, and increasing costs due to the need for worst-case heat load or temperature scenarios.
Innovation Solution
A two-phase liquid-cooled system utilizing independent cooling circuits with engineered fluids that transition between liquid and vapor states to cool devices at different operating temperatures, optimizing thermal design by using fluorinated ketones, hydrofluoroethers, and other engineered fluids with specific phase transition temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cooling system is designed to handle the worst case heat load or operating temperature, then the system can ensure adequate cooling for all devices, but the system requires more space, more energy, and increases overall cost
Solution Approach 1:
The cooling system is divided into multiple independent cooling circuits, each tailored to specific devices with similar thermal characteristics. This segmentation allows each circuit to be optimized for its specific heat load rather than designing one oversized circuit to handle all worst-case scenarios, thereby reducing the total space required while maintaining adequate cooling for all devices.
Solution Approach 2:
Different cooling circuits use different engineered fluids with different phase transition temperatures matched to the specific operating temperature requirements of different devices. This local optimization ensures that each device is cooled at or near its optimal temperature without requiring the entire system to be designed for the worst-case temperature, reducing overall space and energy requirements.
2Reliability
If a cooling system is designed to handle the worst case heat load or operating temperature, then the system can ensure adequate cooling for all devices, but the system consumes more energy
Solution Approach 1:
By segmenting the cooling system into multiple independent circuits, each circuit can be sized and configured for its specific thermal load. This eliminates the energy waste associated with using an oversized cooling system to handle minor thermal loads, as each circuit operates at optimal efficiency for its designated devices.
Solution Approach 2:
The system changes the parameter of phase transition temperature by selecting different engineered fluids for different cooling circuits. This allows each circuit to operate at the optimal temperature range for its devices, maximizing heat transfer efficiency and minimizing the energy required for cooling.
3Loss of energy
If conventional liquid cooling is used, then the system can remove heat effectively, but the heat capacity is limited compared to phase change cooling
Solution Approach 1:
The cooling system utilizes phase change cooling by allowing engineered fluids to transition from liquid to vapor phase within the cooling circuits. This phase transition provides significantly higher heat capacity compared to conventional liquid cooling, enabling more effective heat removal with less coolant volume. The vapor is then condensed and recirculated, creating an efficient closed-loop system.
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 system provides efficient cooling with reduced space, energy, and cost requirements by maintaining different operating temperatures at or near the phase transition temperatures of the engineered fluids, effectively addressing the challenges of varying heat loads and temperatures.
Implementation Method 1
utilizes the phase transition of a fluid from a liquid phase to a vapor phase to accept heat
Implementation Method 2
The engineered liquid is evaporated at a phase transition temperature within the portion of the fluid path to cool the surface
Implementation Method 3
a liquid-to-vapor phase change at a fixed transition temperature has a far greater heat capacity or heat of vaporization than does heating the liquid
Implementation Method 4
The vapor is collected and condensed back to a liquid, which is recirculated to the top of the power transformer
Data Source
AI summary
A two-phased liquid-cooled electrical power apparatus includes a plurality of cooling circuits that recirculate and transition respective engineered fluids between liquid and vapor states around closed-loop fluid paths to cool a plurality of devices. A portion of each fluid path is either integrated with or in thermal contact with its device. The engineered fluids are evaporated within the respective portions of the fluid paths to hold the operating temperatures at or near the respective and different phase transition temperatures. The cooling circuits may be used to maintain different operating temperatures of hollow primary and secondary winding coils in a power transformer, of parallel connect hollow winding excitation coils and a common magnetic core in an electrical reactor, of power semiconductor devices mounted on heat sink(s) in which the fluid paths are embedded or power semiconductor devices in which the respective fluid paths pass through the devices.