Two-Phase Cooling for Circuit Breaker Energy Absorbers
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Solution Overview
Problem
Solid-state and hybrid circuit breakers face challenges in dissipating energy stored in electrical networks, leading to strong temperature increases in metal oxide varistors, which can hinder subsequent switching operations and require costly backup solutions due to prolonged thermal recovery times.
Innovation Solution
A two-phase cooling arrangement is implemented for energy absorbers in circuit breakers, utilizing fluid distribution units to direct a cooling fluid in a liquid state towards the energy absorbers, facilitating evaporation and absorption of sensible heat, thereby accelerating thermal recovery and reducing the need for multiple varistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive air cooling or heat sinks are used to cool energy absorbers, then the cooling system is simple and low cost, but the thermal recovery time is prolonged and heat transfer efficiency is insufficient
Solution Approach 1:
The patent utilizes the phase transition of cooling fluid from liquid to vapor when it contacts the hot energy absorber surface. This phase change process absorbs large amounts of heat rapidly, dramatically reducing thermal recovery time compared to conventional air cooling or heat sink methods that rely on slower conductive and convective heat transfer mechanisms.
Solution Approach 2:
The invention employs a liquid cooling fluid delivery system that directs cooling fluid onto the energy absorber surface. This hydraulic approach enables controlled application of cooling medium to maximize heat transfer efficiency while managing the thermal recovery process effectively.
2Temperature
If multiple energy absorbers are used to ensure adequate cooling capacity, then the cooling performance is sufficient, but the device occupies more space and increases cost
Solution Approach 1:
By utilizing the high heat absorption capacity of phase change from liquid to vapor, the system achieves effective cooling of energy absorbers with a single unit rather than requiring multiple parallel absorbers. This phase change mechanism provides sufficient cooling capacity in a more compact configuration, reducing the overall device area.
3Power
If energy absorbers operate at high temperature to dissipate network energy, then the energy dissipation capability is strong, but the MOVs cannot perform another switching operation for a specific time period
Solution Approach 1:
The cooling system is activated immediately after the energy absorber completes its energy dissipation function. By applying cooling fluid during this post-operation phase, the system begins the thermal recovery process without delay, preparing the MOV for the next switching operation as quickly as possible, thereby maximizing switching operation frequency.
Solution Approach 2:
The rapid phase change from liquid to vapor provides intense cooling that quickly reduces the MOV temperature after high-power operation. This rapid thermal recovery enables the energy absorber to return to operational temperature levels faster, increasing the permissible switching operation frequency.
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 two-phase cooling significantly enhances heat transfer, shortening thermal recovery times, potentially reducing the number of required energy absorbers, saving space and costs, and enabling more frequent switching operations without temperature limits being exceeded.
Implementation Method 1
The energy absorber is cooled due to evaporation of the cooling fluid
Implementation Method 2
absorption of sensible heat, thereby accelerating thermal recovery
Data Source
Figure 1~2b
Figure 3a~3d
Figure 4a~4c
AI summary
An energy absorption device (1) for a circuit breaker, in particular a solid-state or a hybrid circuit breaker, includes an energy absorber (20) arranged within an enclosure (10) and a two-phase cooling arrangement. The two-phase cooling arrangement has one or more fluid distribution units (110) configured to direct a cooling fluid in a liquid state toward the energy absorber (20), the energy absorber (20) being cooled due to evaporation of the cooling fluid. A circuit breaker, in particular solid-state or hybrid circuit breaker, includes one or more energy absorption devices (2, 3, 4). A method for two-phase cooling of an energy absorber (20) of a circuit breaker, in particular a solid-state or hybrid circuit breaker, includes: after a switching operation of the circuit breaker, directing a cooling fluid in a liquid state toward the energy absorber (20). Thereby, the energy absorber (20) is cooled due to evaporation of the cooling fluid.