Regenerative Thermodynamic Cycle Exhaust Stream Splitting
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Solution Overview
Problem
Supercritical Brayton cycle power generation systems face challenges in turbomachinery design due to high fluid density and complex mechanical design requirements, limiting thermal efficiency and operational controllability, especially at off-design conditions.
Innovation Solution
A regenerative thermodynamic cycle configuration that splits the exhaust stream from a high-pressure expander into two streams, directing one to a turbocompressor shaft and the other to a turbogenerator shaft, with each shaft equipped with a low-pressure expander, optimizing fluid flow and reducing mechanical stresses and axial thrust loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If supercritical fluids are used in closed thermodynamic power generation cycles, then thermal efficiency is improved, but device complexity increases due to large number of components and high fluid density
Solution Approach 1:
The exhaust stream from the high-pressure expander is divided into two separate streams, with each stream directed to a dedicated low-pressure expander. This segmentation allows independent optimization of each expander's operating conditions and simplifies the overall turbomachinery design by distributing the complex flow management across multiple simpler units rather than one highly complex single unit.
2Device complexity
If single shaft configuration is used with expander and compressor, then mechanical design is simplified, but operational controllability deteriorates at off-design conditions
Solution Approach 1:
The system separates the drive shaft and free shaft configurations into distinct operational modes. The first low-pressure expander connects to the compressor via a drive shaft for coordinated operation, while the second low-pressure expander connects via a free shaft allowing independent speed control. This segmentation enables the system to maintain simplicity while achieving adaptability through selective coupling.
Solution Approach 2:
The system dynamically adjusts operational configuration by allowing the second low-pressure expander to operate independently on a free shaft when adaptability is needed, and can be coupled to the drive shaft when mechanical simplicity is prioritized. This dynamic reconfigurability enables optimal performance across varying operating conditions.
3Device complexity
If exhaust stream is not split, then device complexity is reduced, but mechanical stresses and axial thrust loads increase
Solution Approach 1:
Dividing the exhaust stream into two separate flows directed to different low-pressure expanders distributes the mechanical load and thermal stress across multiple components. This segmentation prevents any single component from bearing excessive axial thrust loads that would result from handling the entire exhaust stream in a single expander.
Solution Approach 2:
Each low-pressure expander is optimized for specific local conditions of the exhaust stream it receives, allowing tailored design that minimizes mechanical stresses for each component's specific operating parameters rather than requiring a single component to handle all variations.
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 configuration enhances thermal efficiency, reduces mechanical stresses, and allows for balanced operation at varying conditions, improving the overall performance of supercritical Brayton cycle power generation systems.
Implementation Method 1
a high-pressure expander to deliver an exhaust stream
Implementation Method 2
a first low-pressure expander coupled to a pressurization device through a turbocompressor shaft... and a second low-pressure expander coupled to the high-pressure expander and an electrical generator through a turbogenerator shaft
Implementation Method 3
a pressurization device to receive a pressurized working fluid stream
Data Source
Figure 1
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AI summary
A regenerative closed loop thermodynamic power generation, cycle system is presented. The system includes a high-pressure expander to deliver an exhaust stream. A conduit is fluidly coupled to the high-pressure expander, which is configured to split the exhaust stream from the high-pressure expander into a first exhaust stream and a second exhaust stream. The system further includes a first low- pressure expander and a second tow-pressure expander. The first low-pressure expander is coupled to a pressurization device through a turbocompressor shaft, and fluidly coupled to receive the first exhaust stream. The second low-pressure expander is coupled to the high -pressure expander and an electrical generator through a turbogenerator shaft, and fluidly coupled to receive the second exhaust stream. A. method for operating the regenerative closed loop thermodynamic power generation cycle system is also presented