Turbo Compressor Double-Shell Structure for Driving Unit Cooling
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Solution Overview
Problem
Conventional turbo compressors face limitations in achieving high pressure ratios due to workability, mass productivity, and durability issues, and require complex cooling systems that increase compression work and costs, while also being bulky due to the need for separate cooling fluids and radial diffuser designs.
Innovation Solution
A double-shell structure turbo compressor design where the refrigerant compressed by the impeller flows through a shell passage to cool the driving unit, eliminating the need for separate cooling fluids and allowing for axial compression, thereby simplifying the structure and reducing size while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a separate cooling system with cooling fluid is provided for the driving unit, then the driving unit can be cooled effectively, but the structure becomes complex and additional costs and management efforts are required
Solution Approach 1:
The refrigerant serves dual functions: it acts as both the working fluid for compression and the cooling fluid for the driving unit. This eliminates the need for a separate cooling system, reducing structural complexity while maintaining effective cooling of the driving unit through the same refrigerant circulation path
Solution Approach 2:
The cooling function and compression function are merged into a single system using the refrigerant. The refrigerant circulation path is designed to pass through the driving unit for cooling while simultaneously performing the compression cycle, combining two separate functions into one integrated system
2Temperature
If the suction refrigerant is used for cooling the driving unit before compression, then the driving unit is cooled, but the compression work is increased due to rising temperature
Solution Approach 1:
The refrigerant is cooled in advance after compression by passing through the driving unit, rather than cooling it before compression. This preliminary cooling action occurs after the compression process, ensuring that the refrigerant entering the impeller is at optimal temperature while still providing necessary cooling to the driving unit
Solution Approach 2:
Instead of cooling the refrigerant before compression (conventional approach), the invention inverts the sequence by cooling the refrigerant after compression. The refrigerant passes through the driving unit in a reversed flow path, cooling the driving unit while maintaining optimal compression conditions
3Stress or pressure
If a multi-stage turbo compressor with multiple impellers is used to achieve high pressure ratio, then the compression capability is improved, but the structure becomes complex and durability issues arise
Solution Approach 1:
The invention achieves high discharge pressure by optimizing parameters of a single impeller system, including the impeller blade shape, diffuser geometry, and operating speed. By changing these parameters efficiently, the desired pressure ratio is achieved without requiring multiple impellers, thus maintaining structural simplicity and improving durability
4Stress or pressure
If the diffuser space is enlarged to increase compression ratio, then the compression capability is improved, but the radial size of the compressor increases
Solution Approach 1:
The invention transitions from radial expansion to axial expansion for the diffuser space. Instead of increasing the radial size of the diffuser, the diffuser is designed to extend in the axial direction, allowing the compression ratio to be increased while maintaining a compact radial footprint and overall compressor size
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 double-shell structure enables efficient cooling of the driving unit using the discharge refrigerant, reducing compression work, and allows for a slim compressor design with increased capacity, improving operational simplicity and cost-effectiveness while maintaining reliable operation.
Implementation Method 1
a refrigerant compressed by an impeller may flow through a shell passage to cool a driving unit
Implementation Method 2
an impeller that pressurizes a suction refrigerant in the radial direction of a rotary shaft
Data Source
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AI summary
A turbo compressor according to the present invention comprises: a driving unit including a stator and a rotor that generate a rotational force and a rotary shaft that is connected to and rotated by the rotor; an impeller connected to the rotary shaft to pressurize a suction refrigerant in the radial direction of the rotary shaft; and a casing configured to receive the driving unit and the impeller and support the rotary shaft, wherein the casing comprises: a first shell to which the stator is fixed, the first shell rotatably supporting the rotary shaft; and a second shell spaced apart from the first shell to surround the first shell, a shell passage for the refrigerant pressurized by the impeller being defined in a space between the first and second shells. As a result, the discharge refrigerant cools the driving unit, which improves the efficiency of the compressor.