Modular SMA Core Rotary Energy Recovery
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Solution Overview
Problem
Existing shape memory alloy (SMA) engines face challenges in achieving high reciprocating frequencies suitable for industrial applications due to slow contraction and expansion rates, leading to significant parasitic power losses and inefficiencies in energy recovery from low-grade heat.
Innovation Solution
A modular SMA core design with a plurality of SMA elements mounted radially around a shaft, allowing cumulative rotation and enhanced heat transfer, which increases power density and efficiency by amplifying the stroke of SMA wires without increasing the housing height, and eliminates the need for relaxation springs, enabling continuous work output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional SMA engines use single or few SMA elements, then the device complexity is low, but the power density and efficiency are insufficient for industrial applications
Solution Approach 1:
The SMA core is divided into multiple discrete SMA elements (first SMA element, second SMA element, third SMA element, fourth SMA element) arranged radially around the shaft. Each element operates independently but contributes to cumulative rotation, increasing power density while maintaining manageable complexity through modular segmentation
Solution Approach 2:
Multiple SMA elements are nested radially around a central shaft, with each element positioned at different radial distances. This nested arrangement allows compact packaging of multiple actuators in a confined space, enhancing power density without proportionally increasing device footprint
2Productivity
If SMA engines operate at low reciprocating frequencies, then the parasitic power losses are reduced, but the productivity and energy recovery efficiency are insufficient for industrial applications
Solution Approach 1:
Multiple SMA elements are combined to work in sequence around the shaft, with their individual contractions and expansions merging to produce cumulative rotational motion. This synergistic combination allows the system to achieve higher effective productivity while distributing the mechanical stress and heat generation across multiple elements, reducing parasitic losses per element
Solution Approach 2:
The radial arrangement of multiple SMA elements enables continuous rotational output by ensuring that as one element completes its cycle, the next element is ready to contribute to the rotation. This continuous action maintains high productivity while smoothing out peak stress events that would otherwise increase parasitic losses
3Length of moving object
If the housing height is increased to accommodate longer SMA wires for greater stroke, then the stroke amplification is improved, but the compactness and ease of integration are reduced
Solution Approach 1:
Instead of increasing stroke amplification solely through vertical housing height, the invention utilizes radial dimension by arranging SMA elements around the shaft at different radial positions. This dimensional transformation allows stroke amplification to be achieved through radial leverage rather than vertical extension, maintaining compact housing height while achieving greater effective stroke
4Stability of the object's composition
If relaxation springs are included in conventional SMA engines, then the SMA wires can return to their original shape, but the device complexity and energy losses increase
Solution Approach 1:
The SMA elements utilize their inherent shape memory properties to automatically return to their original configuration after deformation, eliminating the need for separate relaxation springs. This self-service mechanism reduces device complexity by removing auxiliary components while maintaining the necessary functional stability of SMA wire recovery
Solution Approach 2:
The relaxation function is extracted from the system by removing relaxation springs entirely. Instead of adding separate components for recovery, the design relies solely on the intrinsic properties of the SMA elements themselves to provide both actuation and recovery functions, simplifying the overall device architecture
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 modular design achieves higher power density and efficiency by amplifying the stroke of SMA wires, reducing parasitic losses, and allowing continuous work output, making it suitable for industrial applications and energy recovery from low-grade heat.
Implementation Method 1
A shape-memory alloy (SMA) is an alloy that 'remembers' its original, cold-forged shape which once deformed returns to its pre-deformed shape upon heating
Implementation Method 2
constructing SMA engines which recover energy from heat as motion
Implementation Method 3
A modular SMA core design with a plurality of SMA elements mounted radially around a shaft, allowing cumulative rotation and enhanced heat transfer, which increases power density and efficiency by amplifying the stroke of SMA wires
Implementation Method 4
a first SMA core housed in a first immersion chamber and adapted to be sequentially filled with fluid to allow heating and/or cooling of the first SMA core
Data Source
AI summary
The invention provides an energy recovery device comprising a first SMA core housed in a first immersion chamber and adapted to be sequentially filled with fluid to allow heating and/or cooling of the first SMA core wherein a first shaft is adapted to be turned by the SMA core mounted concentrically around said first shaft. The SMA core comprises a plurality of SMA elements to define a module, wherein a plurality of modules are mounted in series and whereby movement of a first module is configured to be input to a second module enabling cumulative rotation of the shaft.