Coaxial Modular Pump-Turbine With Sealless Motor Cooling
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Solution Overview
Problem
Existing pump and turbine designs face challenges such as leakage and alignment issues due to dynamic seals, complexity and cost in magnetic coupling, limited scalability, and inefficiencies in cooling and motor/generator integration, which restrict their compactness, modularity, and adaptability for varying applications.
Innovation Solution
A compact, modular, sealless pump or turbine design with a concentric flow configuration that allows multiple modules to be combined in series without bulky interconnections, featuring separate rotor operation, efficient thermal management, and modular motor/generator integration, enabling flexible scaling and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If dynamic seals are used to maintain pressure boundaries at the rotating shaft penetration location, then pressure containment is improved, but leakage and failure modes increase
Solution Approach 1:
The patent removes the rotating shaft and dynamic seal components from the system by implementing a sealless design where the motor is coupled to the impeller through direct magnetic coupling. This extraction of the problematic sealing interface eliminates leakage and failure modes associated with dynamic seals while maintaining pressure containment through the sealed motor housing and magnetic drive mechanism.
Solution Approach 2:
The patent replaces the mechanical shaft and dynamic seal system with a magnetic coupling system. The motor's magnetic field directly drives the impeller without mechanical contact, substituting electromagnetic forces for mechanical transmission. This eliminates the need for dynamic seals at the shaft penetration point while maintaining torque transmission and pressure boundaries.
2Stability of the object's composition
If rigid baseplates are used to mount and align the pump and motor, then alignment stability is improved, but vibration issues and alignment problems under nozzle loads persist
Solution Approach 1:
The patent merges the motor and pump into a single integrated assembly where the motor housing is directly coupled to the pump housing. This integration eliminates the separate rigid baseplate connection, creating a unified structure that reduces alignment issues and vibration problems under nozzle loads while maintaining stable relative positioning through precision manufacturing and integrated mounting features.
3Reliability
If magnetic coupling drives are used to eliminate dynamic seals, then leakage is reduced, but component complexity and cost increase
Solution Approach 1:
The patent combines the motor and pump into a single sealed integration where the magnetic coupling occurs within the sealed motor housing. This merging eliminates the need for separate magnetic coupling components and external shaft seals, reducing overall system complexity while maintaining leakage-free operation. The integrated design allows the motor assembly to serve dual functions as both the drive mechanism and the sealed containment.
4Reliability
If radial field motor design is used in integral pump, then sealless operation is achieved, but rotor housing diameter and length increase significantly
Solution Approach 1:
The patent inverts the traditional radial field motor configuration by implementing an axial field motor design where the magnetic flux path is oriented axially rather than radially. This inversion allows for a more compact rotor housing with reduced diameter and length while maintaining the sealless operation benefit. The axial field configuration enables the motor to generate the same torque in a more space-efficient manner.
5Power
If axial field motor design is used to achieve compactness, then power density is improved, but cooling of motor coils becomes difficult
Solution Approach 1:
The patent introduces a cooling fluid as an intermediary medium to transfer heat from the motor coils. The cooling fluid circulates through channels in the motor housing and stator, absorbing heat from the motor coils and carrying it away from the compact axial field motor assembly. This intermediary cooling mechanism enables effective thermal management in the space-constrained axial field configuration.
Solution Approach 2:
The patent employs hydraulic cooling where a liquid cooling fluid circulates through integrated cooling channels in the motor housing and stator components. This hydraulic cooling system efficiently removes heat from the high-density axial field motor coils by convective heat transfer, enabling the compact motor design to operate at high power density without overheating.
6Temperature
If working fluid is shunted through cooling passages to cool motor coils, then thermal management is improved, but pump efficiency decreases due to fluid diversion
Solution Approach 1:
The patent implements a dedicated hydraulic cooling system with separate cooling channels that do not divert the main working fluid flow. The cooling fluid circulates through independent passages in the motor housing and stator, thermally coupling to the motor coils without interfering with the primary pump flow path. This separate hydraulic cooling circuit maintains pump efficiency while providing effective motor coil cooling.
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 design enhances compactness, scalability, and reliability by eliminating dynamic seals, optimizing thermal management, and allowing independent control of modules, thereby improving efficiency and reducing the risk of failure while accommodating various pressure and flow rate requirements.
Implementation Method 1
The shunted working fluid is heated by convection from the stator wall and carries the heat away from the stator to be expelled along with the un-shunted working fluid
Implementation Method 2
the coil housing, i.e. stator housing, of the motor or generator is concentrically surrounded by the outer housing of the module, thereby creating an annular space therebetween surrounding the motor or generator coils
Data Source
Figure 1
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Figure 2B
AI summary
A coaxial pump or turbine module includes an integral, modular motor or generator comprising a magnet structure containing radial or axial permanent magnets and/or induction coils detachably fixed to a rotor, and a stator housing detachably fixed to the module housing. Working fluid is directed axially through a flow path symmetrically distributed within an annulus formed between the module housing and the stator housing. The stator housing can be cooled by the working fluid, or by a cooling fluid flowing between passages of the flow path. The flow path can extend over substantially a full length and rear surface of the stator housing. A plurality of the modules can be combined into a multi-stage apparatus, with rotor speeds independently controlled by corresponding variable frequency drives. Embodiments include guide vanes and/or diffusers. The rotor can be fixed to a rotating shaft, or rotate about a fixed shaft.