Strayton Engine Combining Brayton and Stirling Cycles
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Solution Overview
Problem
Current power generation technologies, such as the Brayton and Stirling cycles, face limitations in scalability, efficiency, and specific power due to turbine cooling challenges and mass constraints, with closed Brayton cycles being less efficient than open cycles and Stirling cycles not scaling well to higher power applications.
Innovation Solution
A combined Brayton and thermoacoustic Stirling cycle engine, referred to as the Strayton engine, where the Stirling cycle is embedded within the Brayton cycle to provide conductive cooling and thermal recuperation, enhancing efficiency and specific power through a synergistic thermodynamic cycle that acts as both a topping and bottoming cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If turbine blade cooling is implemented to achieve higher efficiency and specific power, then system efficiency and specific power increase, but system mass increases due to additional cooling components
Solution Approach 1:
The patent merges the Brayton cycle turbine system with a Stirling cycle refrigeration system into a single integrated apparatus. The Stirling cycle engine is positioned within the turbine housing and shares common structural elements, allowing the refrigeration system to provide blade cooling without requiring separate cooling components, thus increasing specific power without proportionally increasing system mass
Solution Approach 2:
The Stirling cycle engine is nested within the turbine housing structure, with the piston assembly located inside the turbine case. This nesting arrangement allows the cooling system to be housed within existing structural boundaries, minimizing additional mass while providing the necessary cooling function for higher efficiency operation
2Object-generated harmful factors
If closed Brayton cycle is used instead of open cycle, then system complexity is reduced and emissions are eliminated, but system efficiency decreases
Solution Approach 1:
The patent converts the typically wasted thermal energy from the Brayton cycle exhaust into useful refrigeration capacity by feeding it to the Stirling cycle engine. The exhaust heat that would otherwise be lost is now utilized to drive the Stirling piston, producing cooling effects while maintaining high overall system efficiency and eliminating emissions
Solution Approach 2:
The integrated apparatus performs multiple functions simultaneously: the Brayton cycle generates power while the Stirling cycle provides refrigeration using the Brayton exhaust heat. This multi-functionality allows the closed cycle system to achieve both emissions elimination and high efficiency by making productive use of all thermal energy in the system
3Loss of energy
If Stirling cycle is used for high power applications, then thermal efficiency is maintained, but scalability is limited due to oscillating component amplitude and thermal surface heat transfer limits
Solution Approach 1:
The patent combines the Stirling cycle refrigeration system with a Brayton cycle power generation system, allowing the Stirling engine to operate at optimized temperatures for high thermal efficiency while the Brayton cycle handles the high power generation. The two cycles work synergistically, with the Stirling cycle providing cooling that enables the Brayton turbine to operate at higher temperatures and power levels
Solution Approach 2:
The patent segments the power generation and refrigeration functions into two separate thermodynamic cycles operating at different scales. The Brayton cycle handles the high power generation function while the Stirling cycle handles the refrigeration function, allowing each cycle to be optimized for its specific function without being constrained by the other's scaling limitations
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 Strayton engine achieves higher efficiency and specific power by conductively cooling turbine blades, reducing the need for turbine blade cooling flow, and utilizing waste heat for thermal recuperation, resulting in increased efficiency and reduced system mass, with the potential for higher turbine inlet temperatures and zero-emission operation.
Implementation Method 1
The Stirling cycle engine includes a cold side heat exchanger disposed adjacent to the compressor, a hot side heat exchanger disposed adjacent to the turbine
Implementation Method 2
a regenerator disposed between the cold and hot side heat exchangers
Implementation Method 3
A combined Brayton and thermoacoustic Stirling cycle engine
Implementation Method 4
a Stirling cycle engine disposed within the hollow rotating shaft
Data Source
AI summary
A system is described which includes a Brayton cycle engine having a compressor, a turbine, a hollow rotating shaft that extends between a first end and a second end, a hollow tubing that interconnects the first end and the second end, and a heat source; a thermoacoustic Stirling cycle engine disposed within the hollow rotating shaft between the first and second ends thereof, the Stirling cycle engine including a cold side heat exchanger disposed adjacent to the compressor, a hot side heat exchanger disposed adjacent to the turbine, and a regenerator disposed between the cold and hot side heat exchangers; a first power generator disposed within the hollow tubing and located adjacent to the second end of the hollow rotating shaft; and, a second power generator disposed around the hollow rotating shaft between the first and second ends. The system can be arranged in a quad configuration having four stages.