Rotor Cooling System Using Solid-Liquid Phase Change Heat Pipe
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Solution Overview
Problem
Conventional heat pipe systems are limited in their heat transfer capacity and reliability for high power, compact rotating shafts or rotor assemblies, particularly in electric motors and generators, due to size constraints and mechanical complexity, which affects uniform cooling and system reliability.
Innovation Solution
A solid-liquid phase change heat pipe system with an internal 'surface-scraping' mechanism is introduced, utilizing a rotating hollow tube filled with a phase change material and a scraper assembly to enhance heat transfer rates, where the scraper assembly removes solidified material from the inner surface, allowing for high cooling rates and efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional liquid-vapor heat pipes are used for rotor cooling, then the system structure is simple, but the heat transfer capacity is insufficient for high power applications
Solution Approach 1:
The patent employs solid-liquid phase change of the cooling medium within the rotor. The phase transition occurs between the solid and liquid states of the cooling fluid, enabling efficient heat absorption and transport throughout the rotor assembly, thereby significantly increasing heat transfer capacity compared to conventional liquid-vapor heat pipes
Solution Approach 2:
The patent changes the operating parameters of the heat pipe system by using solid-liquid phase change instead of liquid-vapor phase change. This parameter change allows the system to achieve higher heat transfer capacity while maintaining a compact structure suitable for high power density applications
2Weight of moving object
If the rotor assembly is made compact for mobile applications, then weight and size are reduced, but heat dissipation becomes more difficult
Solution Approach 1:
The solid-liquid phase change mechanism provides high latent heat absorption capacity within the compact rotor volume. This enables effective heat dissipation in a small, lightweight rotor assembly suitable for mobile electric vehicle applications where weight and size are critical constraints
Solution Approach 2:
The cooling medium is nested within the rotor assembly structure itself, with the phase change material contained in channels or cavities integrated into the rotor. This nesting approach allows the cooling system to be part of the rotor structure, minimizing additional weight and volume while maximizing heat dissipation efficiency
3Stability of the object's composition
If conventional heat pipe systems are used, then the system is simple to implement, but uniform cooling of the rotor assembly is difficult to achieve
Solution Approach 1:
The solid-liquid phase change occurs throughout the entire rotor volume, providing uniform heat absorption and temperature distribution. The phase transition propagates through the cooling medium, ensuring consistent cooling across all rotor components including windings, magnets, and structural elements
Solution Approach 2:
The phase change cooling system serves multiple functions simultaneously: it cools the rotor windings, magnets, and structural components through a single integrated mechanism. The cooling medium circulates through channels that contact all critical rotor elements, providing universal cooling coverage
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 solid-liquid heat pipe system achieves high heat transfer rates and increased heat transport capacity compared to conventional liquid-vapor heat pipes, ensuring reliable and efficient temperature control for rotating assemblies by leveraging centrifugal forces and continuous phase change material circulation, while being compact and reliable.
Implementation Method 1
a rotating hollow tube filled with a phase change material
Implementation Method 2
The solid-liquid heat pipe system achieves high heat transfer rates and increased heat transport capacity
Implementation Method 3
leveraging centrifugal forces and continuous phase change material circulation
Implementation Method 4
a scraper assembly to enhance heat transfer rates, where the scraper assembly removes solidified material from the inner surface
Data Source
AI summary
A rotating heat pipe is used for temperature control of electric motors and generators and other rotating heat generating assemblies to ensure their proper operation. The heat pipe is integral with the shaft, and unlike conventional devices, incorporates a solid-liquid phase change material as the heat transfer/transport material. In addition, it comprises a scraped surface heat exchange mechanism at the heat dissipation region to allow for high cooling rates as required. This scraped surface mechanism is preferentially driven by a magnetic coupling to eliminate issues related to leaks of the heat transfer material.