Capillary Pumped Heat Transfer Loop for Railway Traction Converter
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Solution Overview
Problem
Current electrical power converters in railway vehicles are bulky and require significant maintenance due to the use of glycol water cooling circuits with hydraulic pumps, leading to high operating and maintenance costs.
Innovation Solution
A compact capillary pumped heat transfer loop is used, eliminating the need for electromechanical pumps by employing a two-phase cooling fluid that circulates through capillary evaporators and a condensation stage, with a thermally controlled two-phase pressurizing tank regulating the junction temperature of switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If glycol water cooling circuits with hydraulic pumps are used, then heat dissipation is achieved, but the device becomes bulky and requires significant maintenance
Solution Approach 1:
The patent removes the hydraulic pump from the cooling circuit, extracting the problematic electromechanical component that caused bulkiness and maintenance issues. The capillary pumped loop eliminates the need for external pumping mechanisms by using capillary forces within the evaporator structure to drive fluid circulation.
Solution Approach 2:
The patent replaces the mechanical hydraulic pump system with a capillary-driven two-phase heat transfer system. Instead of using mechanical pumping to circulate coolant, the system utilizes phase change (liquid to vapor and back) and capillary action to achieve fluid circulation and heat transfer.
2Quantity of substance
If hydraulic pumps are used in cooling circuits, then fluid circulation is maintained, but operating and maintenance costs increase
Solution Approach 1:
The capillary pumped loop is a self-regulating system that automatically circulates coolant through capillary forces and phase change without requiring external control or maintenance. The system self-adjusts fluid flow based on thermal load conditions, eliminating the need for pump maintenance and reducing operational complexity.
Solution Approach 2:
The patent replaces the mechanical pump system with a passive capillary-driven system that uses the physical properties of the two-phase fluid and capillary structures to achieve automatic fluid circulation, eliminating mechanical wear and maintenance requirements.
3Volume of stationary object
If compact design is achieved, then space is reduced, but heat dissipation efficiency may be compromised
Solution Approach 1:
The patent utilizes phase transitions (liquid to vapor in evaporator, vapor to liquid in condenser) to achieve highly efficient heat transfer in a compact volume. The latent heat of vaporization allows for large amounts of heat to be transferred through small temperature differences and compact heat exchanger surfaces.
Solution Approach 2:
The cooling system is segmented into distinct functional zones (evaporator, condenser, capillary structures) that can be efficiently integrated. The segmentation of heat transfer paths allows for optimized heat dissipation in each zone while maintaining overall compactness.
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 solution reduces maintenance requirements and operating costs by providing efficient heat dissipation with a compact design, maintaining a constant junction temperature despite varying power consumption, and ensuring the purity and efficiency of the cooling fluid.
Implementation Method 1
a two-phase heat transfer fluid; a first heat exchanger applied against said electrical power component; a second heat exchanger able to evacuate the heat from the heat transfer fluid out of the cooling loop
Implementation Method 2
A compact capillary pumped heat transfer loop is used, eliminating the need for electromechanical pumps by employing a two-phase cooling fluid that circulates through capillary evaporators
Implementation Method 3
a condensation stage
Implementation Method 4
with a thermally controlled two-phase pressurizing tank regulating the junction temperature of switching elements
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The converter (10) has a closed cooling loop (14) comprising a heat exchanger applied against an electric power component i.e. semiconductor switching unit (22). The heat exchanger comprises capillary evaporators (30A-30D), where each evaporator has a capillary wick to assure complete vaporization of coolant i.e. methanol, received at liquid state, at the level of meniscus in the wick. The coolant circulates in the cooling loop under the effect of pressure generated at the level of a liquid/vapor interface in the evaporator, for forming a capillary pumping loop.