Evaporating Unit Layout for Uniform Power Electronics Cooling
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Solution Overview
Problem
Current two-phase cooling systems for power electronic devices face challenges in maintaining efficient cooling performance while minimizing thermal vulnerabilities and costs, particularly due to temperature non-uniformities and hot spots caused by sub-cooled liquids, which can lead to premature device failure.
Innovation Solution
The design of an evaporating unit with a thermo-conducting wall and a pre-heating mechanism that positions the inlet channel outside the cooling surface portion, allowing the cooling fluid to be pre-heated close to its liquid-gas phase transition point, thereby avoiding sub-cooling and enhancing heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a two-phase cooling circuit is used to cool power electronic devices, then cooling performance is improved, but temperature non-uniformities and hot spots occur due to sub-cooled liquids
Solution Approach 1:
The inlet channel is positioned to allow cooling fluid to be pre-heated by the heat emitting device before entering the evaporation channels. This preliminary heating action raises the fluid temperature closer to the saturation point, preventing sub-cooling effects and the associated temperature non-uniformities and hot spots that compromise device reliability.
Solution Approach 2:
The inlet channel acts as an intermediary element between the heat emitting device and the evaporation channels. It mediates the thermal interaction by allowing the cooling fluid to absorb some heat from the device before full evaporation occurs, thereby smoothing temperature distribution and eliminating harmful sub-cooling effects.
2Volume of moving object
If the inlet channel is positioned inside the cooling surface portion, then compact design is achieved, but sub-cooling occurs causing temperature non-uniformities
Solution Approach 1:
The cooling system is designed with differentiated functional zones: the inlet channel is positioned in a transition zone outside the main cooling surface portion where it performs pre-heating, while the evaporation channels are located in the cooling surface portion for active cooling. This local differentiation of functions allows compact design while maintaining temperature uniformity.
3Productivity
If cooling fluid is introduced at low temperature, then cooling efficiency is increased, but temperature non-uniformities and hot spots are created
Solution Approach 1:
The temperature parameter of the cooling fluid is dynamically adjusted through the pre-heating process in the inlet channel. The fluid temperature is raised from its initial low state to closer to the saturation point before entering the evaporation channels, thereby maintaining high cooling efficiency through phase change while eliminating temperature non-uniformities and hot spots.
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 approach improves cooling efficiency by maintaining the cooling fluid near its saturation point, reducing temperature non-uniformities and hot spots, and extending the lifespan of heat emitting devices while maintaining a compact and cost-effective cooling system configuration.
Implementation Method 1
the cooling fluid inside of the first inlet channel is pre-heated by the at least one heat emitting device before entering the fluid distributor
Implementation Method 2
the cooling fluid is heated in the first plurality of evaporation channels by the heat from the at least one heat emitting device and thereby at least partially vaporized
Implementation Method 3
the cooling fluid is heated inside of the evaporating unit by the dissipated heat from the heat emitting device and reaches a boiling temperature
Implementation Method 4
Within the condenser the vapour is changed into a liquid by emitting heat. For example, in the condenser the heat is emitted to a coolant medium, such as air at ambient temperature
Data Source
AI summary
An exemplary evaporating unit for cooling a heat emitting device includes a cooling circuit having a stack of evaporating units arranged alternately with heat emitting devices. Each evaporating unit is connected to a condenser and includes a first inlet channel, a first plurality of evaporation channels, and a first outlet channel. The evaporating unit is designed for pre-heating the cooling fluid flowing therein.