Multi-Tank Pressure Inventory Control in Closed Brayton Cycles
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Solution Overview
Problem
Current closed thermodynamic cycle power generation and energy storage systems, such as reversible Brayton cycles, face challenges in efficiently managing working fluid pressure and thermal energy storage, leading to suboptimal power control and roundtrip efficiency.
Innovation Solution
The system incorporates a closed cycle fluid path with high and intermediate pressure tanks, controlled fluid connections, and heat exchangers to regulate the working fluid's pressure and temperature, allowing for variable pressure inventory control and improved thermal energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressure tank is used to store working fluid, then the system structure is simpler, but the pressure control precision and power generation efficiency are reduced
Solution Approach 1:
The single pressure tank is divided into multiple pressure tanks (first pressure tank, second pressure tank, third pressure tank) with different pressure levels. This segmentation allows for more precise control of working fluid quantity and pressure, thereby improving power generation efficiency while maintaining manageable system complexity through modular design.
Solution Approach 2:
Each pressure tank is assigned a specific pressure level and functional role in the working fluid circulation system. The first pressure tank operates at high pressure for power generation, the second at intermediate pressure for transition, and the third at low pressure for fluid return, optimizing local conditions for each stage of the thermodynamic cycle.
2Power
If the quantity of working fluid is increased to enhance power generation, then the power output increases, but the system pressure becomes unstable
Solution Approach 1:
The system dynamically adjusts the quantity of working fluid in the closed cycle by controlling fluid exchange between multiple pressure tanks. The controller monitors system conditions and regulates valves to add or remove working fluid from specific tanks, enabling real-time optimization of power output while maintaining pressure stability through controlled fluid distribution across different pressure zones.
Solution Approach 2:
The intermediate pressure tank serves as a buffer and transition zone between the high-pressure first pressure tank and the low-pressure third pressure tank. This intermediary tank stabilizes pressure fluctuations by absorbing excess fluid during high-power operation and releasing fluid when pressure drops, thereby decoupling the direct pressure relationship between high and low pressure sides.
3Adaptability or versatility
If fluid connections are frequently adjusted to control power output, then the power control flexibility improves, but the system response time increases
Solution Approach 1:
Multiple pressure tanks are pre-configured with different pressure levels and working fluid quantities before operation. When power adjustment is needed, the controller simply switches between pre-established tank configurations rather than gradually adjusting single-tank parameters, significantly reducing the time required for power output changes while maintaining flexibility.
Solution Approach 2:
The control system extracts and isolates the fluid connection adjustment function into a dedicated switching mechanism that can rapidly connect or disconnect specific tanks from the closed cycle. This separation of control function allows for swift reconfiguration of the working fluid path without affecting other system components, thereby reducing response time while preserving control flexibility.
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 power control and roundtrip efficiency by optimizing the circulation of the working fluid through the system, enabling better thermal energy storage and conversion.
Implementation Method 1
a heat exchanger may be employed to transfer heat between a thermal storage material and a working fluid for use with turbomachinery
Implementation Method 2
a compressor, a hot side heat exchanger, a turbine, and a cold side heat exchanger
Implementation Method 3
a turbine, and a compressor... a motor/generator may be used to obtain work from the thermal energy in the system
Data Source
AI summary
Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.