Gravity-Driven Cooling Circuit for Generator Switches
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Solution Overview
Problem
Generator switch cooling devices with heat pipes have low thermal efficiency and require auxiliary gases to withstand high dielectric stresses, complicating their operation and reliability.
Innovation Solution
A gravity-driven cooler with a closed annular cooling circuit using a hydrofluorocarbon or hydrofluoroolefin coolant, eliminating the need for auxiliary gases and enhancing thermal efficiency by separating coolant vapor and liquid phases, and incorporating a sensor for coolant level monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat pipe cooling device is used, then the cooling function is provided, but the thermal efficiency is low and auxiliary gases are required
Solution Approach 1:
The cooling device is segmented into separate liquid and vapor phases with dedicated flow paths. The liquid coolant flows through a liquid conduit from condenser to evaporator, while vapor flows through a vapor conduit from evaporator to condenser. This segmentation allows each phase to be optimized independently, eliminating the need for auxiliary gases and improving thermal efficiency.
Solution Approach 2:
The auxiliary gas component is extracted and removed from the system entirely. The patent achieves the cooling function using only the coolant substance in liquid and vapor phases, eliminating the need for dielectrically robust auxiliary gases like air, nitrogen, or sulfur hexafluoride that were required in conventional heat pipe designs.
2Reliability
If auxiliary gases are used in the cooling device, then dielectric stress is withstood, but device complexity and maintenance increase
Solution Approach 1:
The auxiliary gas component is extracted and removed from the system entirely. The patent achieves the cooling function using only the coolant substance in liquid and vapor phases, eliminating the need for dielectrically robust auxiliary gases like air, nitrogen, or sulfur hexafluoride that were required in conventional heat pipe designs.
Solution Approach 2:
The coolant substance serves multiple functions simultaneously: it provides cooling through phase change and also withstands dielectric stress in the insulating gap. This multi-functionality eliminates the need for separate auxiliary gases, reducing device complexity and maintenance requirements.
3Reliability
If coolant level is not monitored, then device simplicity is maintained, but operational reliability decreases
Solution Approach 1:
The mechanical/complex monitoring system is replaced with a simple level sensor that detects coolant levels. This sensor can be a float mechanism, capacitive sensor, or other simple detection device that provides reliable coolant level monitoring without adding significant complexity to the overall 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
The solution achieves higher thermal efficiency and operational reliability by eliminating the need for auxiliary gases and ensuring reliable coolant circulation, reducing dielectric stress and maintenance complexity.
Implementation Method 1
The cooling device comprises an evaporator, thermally connected to the conductor and operating at high-voltage potential... The thermal efficiency of such a cooling device is comparatively low... the coolant is exposed to strong electric fields when passing through the insulator
Implementation Method 2
Generator circuit breakers with cooling devices for cooling conductors at high-voltage potential utilize the advantageous properties of a coolant/working fluid that can absorb a large amount of heat when transitioning into the vapor phase
Implementation Method 3
a condenser at ground potential... coolant vapor (vaporous coolant) is conveyed from the evaporator to the condenser
Implementation Method 4
A generator switch with a cooling device according to the invention is disclosed... features a gravity-driven cooling device with an evaporator and a condenser located above the evaporator
Implementation Method 5
an insulator for guiding the liquid coolant and coolant vapor, which serves to separate ground and high-voltage potential... Since the coolant is exposed to strong electric fields when passing through the insulator, the coolant is a highly dielectrically resilient fluid
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The invention relates to a generator switch (1) which comprises an enclosure (2) that is at earth potential and an electric conductor (5) at high voltage potential which is arranged inside the enclosure (2) for insulation; and a gravity-driven cooling device (3) with an evaporator (10) and a condenser (20) arranged above the evaporator (10) and a coolant (4). The cooling device (3) is in the form of a closed annular coolant circuit. When the generator switch is operated, a level of the liquid coolant (4) in the conduit system (30) is, when the cooling device (3) is inactive, at least as high as the upper end of the insulating section in the insulator (40).