Aircraft Electric Motor Cooling With Liquid-Vapor Flow Separation
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Solution Overview
Problem
Traditional electric motors for aircraft applications face thermal management limitations due to internal thermal resistance, which restricts heat dissipation and electrical current, leading to weight and volume additions from conventional cooling methods like natural convection and liquid cooling.
Innovation Solution
The implementation of a dual-phase cooling system with a separator to direct a liquid portion to the motor windings and a vapor portion to the drive unit, utilizing a saturated refrigerant like hydrofluorocarbons, hydrofluro-olefins, or hydrofluoroethers, and incorporating a heat exchanger and mixer to optimize cooling fluid flow and manage thermal loads efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods (natural convection or liquid cooling) are used, then heat dissipation is achieved, but volume and weight increase due to the addition of cooling jackets
Solution Approach 1:
The cooling channels are integrated directly into the stator structure, merging the cooling system with the motor body. This eliminates the need for separate cooling jackets, thereby reducing volume and weight while maintaining effective heat dissipation from the windings
Solution Approach 2:
The cooling channels are nested within the stator structure itself, with channels formed inside the stator body or between stator components. This nesting approach allows the cooling system to occupy space already required by the motor structure, avoiding additional external volume and weight
2Temperature
If conventional cooling methods (natural convection or liquid cooling) are used, then heat dissipation is achieved, but volume increases due to the addition of cooling jackets
Solution Approach 1:
The cooling channels are merged with the stator structure, eliminating the need for external cooling jackets. This integration reduces the overall motor volume while maintaining adequate cooling capacity for the windings
Solution Approach 2:
Cooling channels are nested within the stator body or between stator components, utilizing existing structural space for dual purposes (structural support and heat dissipation). This nesting reduces the external volume required for the motor
3Power
If internal thermal resistance is reduced to improve heat dissipation, then electrical current capacity increases, but thermal management complexity increases
Solution Approach 1:
The cooling system is segmented into multiple channels distributed throughout the stator structure, with each channel serving specific winding regions. This segmentation allows targeted cooling of high-heat-generation areas, improving current capacity while maintaining manageable system complexity through modular channel design
Solution Approach 2:
Different regions of the stator are provided with cooling channels according to their specific thermal requirements. Areas with higher current density and heat generation receive dedicated cooling channels, while lower-heat regions have reduced or no cooling infrastructure, optimizing thermal management efficiency
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 enhances thermal efficiency, reduces weight, and improves power density by ensuring critical components receive sufficient coolant, allowing for higher operating temperatures and loads while maintaining a compact design.
Implementation Method 1
cooling channels arranged to provide cooling to the plurality of windings... liquid cooling path configured to direct flow of the working fluid through, at least, the cooling channels of the motor unit
Implementation Method 2
separator arranged upstream of each of the liquid cooling path and the vapor cooling path and configured to direct a liquid portion of the working fluid into the liquid cooling path and configured to direct a vapor portion of the working fluid into the vapor cooling path
Implementation Method 3
heat exchanger arranged along the cooling fluid flow path and configured to cool the working fluid to a liquid state... air is a second fluid of the heat exchanger, wherein the air passed through the heat exchanger to cool the working fluid
Data Source
AI summary
Aircraft electric motors include a motor unit having a rotor and a stator. The stator includes a plurality of windings and cooling channels arranged to provide cooling thereto. A drive unit is configured to drive operation of the motor unit. A cooling system includes a working fluid arranged within a cooling fluid flow path, wherein the cooling fluid flow path includes a liquid cooling path configured to direct flow of the working fluid through, at least, the cooling channels of the motor unit and a vapor cooling path configured to direct flow of the working fluid through the drive unit and a separator arranged upstream of each of the liquid cooling path and the vapor cooling path and configured to direct a liquid portion of the working fluid into the liquid cooling path and configured to direct a vapor portion of the working fluid into the vapor cooling path.