Modular Free-Piston Stirling Machine with Integrated Piston Buffer
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Solution Overview
Problem
Existing stirling machines face challenges in scalability, vibration, and internal fluid flow distribution due to large size, and require complex external components and separate buffer spaces for load or motoring devices and regenerators.
Innovation Solution
The development of free-piston stirling-cycle machines with modular, dynamically balanced configurations in radial and co-axial cylindrical arrangements, where the regenerator is integrated within the piston assembly, and heat exchangers are positioned on inward-facing and outward-facing cylindrical surfaces, allowing for compact design, reduced external heat-flux loadings, and simplified thermal connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If free-piston stirling machines are designed with separate buffer spaces for load or motoring devices, then the machines can maintain proper mechanical coupling and force transmission, but the device complexity increases and the overall size increases
Solution Approach 1:
The patent merges the buffer space function with the piston assembly by integrating the load or motoring device directly into the piston structure. The piston body incorporates cavities that serve as buffer spaces, eliminating the need for separate external buffer spaces while maintaining proper mechanical coupling and force transmission between the piston and load.
Solution Approach 2:
The piston assembly is designed to perform multiple functions simultaneously: it serves as both the moving boundary for the working fluid and as the mounting structure for the load or motoring device. The piston body's cavities provide both structural support and buffer space functionality, reducing the overall number of components needed in the system.
2Volume of stationary object
If free-piston stirling machines are designed with large size to accommodate all components, then the machines can contain all necessary elements, but the internal fluid flow distribution becomes poor and vibration increases
Solution Approach 1:
The patent divides the machine into multiple modular piston assemblies arranged in a distributed configuration. Each piston assembly is a self-contained module with its own working fluid circuit, allowing for better internal fluid flow distribution within each module while maintaining a compact overall machine size. This segmentation prevents the fluid flow distribution problems associated with large single-chamber designs.
3Ease of operation
If free-piston stirling machines are designed with external heat exchangers, then the thermal connections can be simplified, but the external heat-flux loadings increase and the overall complexity increases
Solution Approach 1:
The heat exchangers are nested within the piston assembly structure rather than being mounted externally. The heat exchanger components are integrated into the piston body cavities and surrounding structures, allowing thermal connections to be made through the piston assembly itself. This nesting approach reduces external heat-flux loadings by distributing the thermal exchange surfaces within the compact piston volume while maintaining simplified thermal connection paths.
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 solution enables scalable high-power stirling machines with reduced vibration, simpler internal heat exchangers, and a compact moving magnet linear motor, eliminating the need for separate buffer spaces and reducing wire length, while maintaining efficient thermal and mechanical performance.
Implementation Method 1
a compact moving magnet linear motor, eliminating the need for separate buffer spaces
Implementation Method 2
a regenerator containing a porous matrix with excellent heat transfer and minimal flow resistance that changes the temperature of the fluid passing through it
Implementation Method 3
heat exchangers are positioned on inward-facing and outward-facing cylindrical surfaces, allowing for compact design, reduced external heat-flux loadings, and simplified thermal connections
Implementation Method 4
All stirling machines function by alternately expanding and compressing a working fluid, usually a gas like helium
Implementation Method 5
free-piston stirling-cycle machines
Implementation Method 6
free-piston stirling-cycle machines with modular, dynamically balanced configurations in radial and co-axial cylindrical arrangements, where the regenerator is integrated within the piston assembly
Data Source
AI summary
Multiple free-piston stirling-cycle machine modules are connected together in double-acting configurations that may be used as engines or heat pumps and scaled to any power level by varying the number of modules. Reciprocating piston assemblies oriented in balanced pairs reduce vibration forces. There are no buffer spaces. Linear motors or generators are packaged inside piston cavities entirely within the module working spaces. The external heat-accepting and heat-rejecting surfaces in one embodiment are directed along inward-facing and outward facing cylinders, and in another embodiment along parallel planes, simplifying thermal connections to the external heat source and sink.