SMA Wire Dimension Optimization for Energy Recovery

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Solution Overview

Problem

Existing energy recovery devices using Shape-memory Alloys (SMAs) or Negative Thermal Expansion materials face inefficiencies due to uneven heating and stress distribution caused by fluid dynamics, leading to uneven activation of SMA wires, resulting in energy losses and suboptimal power generation from low-grade heat.

Innovation Solution

The use of SMA or NTE elements arranged as parallel wires with varying diameters and tapered configurations to ensure even activation times across the core, matching wire dimensions to fluid flow characteristics and heat transfer rates to minimize energy losses and achieve balanced stress distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If SMA wires with uniform dimensions are used in the core, then the device structure is simple, but the wires activate unevenly due to fluid dynamics and heat transfer variations, causing energy losses

Engineering Contradiction:
Improvewire uniformityVSAvoidenergy loss from uneven activation
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent applies local quality by varying the dimensions of SMA wires specifically in regions where heat transfer and fluid dynamics differ. Wires closer to the fluid inlet have different dimensions than those farther away, creating localized adaptations that compensate for position-dependent thermal and fluid effects, thereby achieving uniform activation across all wires

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes physical parameters of the SMA wires, specifically their dimensions (diameter, length), to optimize activation timing. By adjusting wire dimensions as a function of position within the core, the system compensates for variations in heat transfer coefficients and fluid flow characteristics at different locations

Inventive Principle:
Principle #35Parameter changes

2Productivity

If SMA wires are positioned to maximize stress distribution, then power generation efficiency improves, but activation timing becomes uneven due to varying thermal and fluid exposure

Engineering Contradiction:
Improvepower generation efficiencyVSAvoidactivation time variation
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent positions and dimensions wires based on their specific location within the core, creating local optimizations that balance thermal exposure, fluid dynamics, and stress distribution. Each wire's dimensions are tailored to its position to achieve simultaneous activation while maintaining optimal stress characteristics for power generation

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces asymmetry in wire dimensions and positioning to counteract the asymmetric thermal and fluid field within the core. By deliberately creating non-uniform wire characteristics that mirror and compensate for the asymmetric environment, the system achieves uniform activation timing across all wires

Inventive Principle:
Principle #4Asymmetry

3Loss of energy

If the core uses wires with varying dimensions for even activation, then energy losses are reduced, but manufacturing complexity increases

Engineering Contradiction:
Improveenergy loss from uneven activationVSAvoidwire dimension variation
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent systematically varies wire parameters (dimensions, positioning) based on position within the core to compensate for thermal and fluid dynamics variations. This controlled parameter changes approach reduces energy losses from uneven activation while maintaining a manageable level of manufacturing complexity through predictable, position-based variations

Inventive Principle:
Principle #35Parameter changes

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 enables more efficient power generation by ensuring all SMA wires activate simultaneously, optimizing stress distribution and reducing energy losses, thereby enhancing the energy recovery process from low-grade heat sources.

Implementation Method 1

activation of at least one wire comprises a transformation from a martensite to an austenite state

Methodology Applied
Scientific EffectPhase transformation (martensite to austenite): Phase Change

Implementation Method 2

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

Methodology Applied
Scientific EffectShape memory effect: Shape Memory Alloy

Implementation Method 3

a plurality of Shape-Memory Alloy (SMA) or Negative Thermal Expansion (NTE) elements arranged as a plurality of wires

Methodology Applied
Scientific EffectNegative thermal expansion: Negative Thermal Expansion

Data Source

PatentEP3317536B1SMA bundle wire optimisation in an energy recovery device
Publication Date: 2019.08.07 EXERGYN
  • EP3317536B1 patent drawingFigure 1
  • EP3317536B1 patent drawingFigure 2~3
  • EP3317536B1 patent drawingFigure 4~5

AI summary

The invention provides an energy recovery device comprising a plurality of Shape Memory Alloy (SMAs) or Negative Thermal Expansion (NTE) elements arranged as a plurality of wires positioned substantially parallel with each other to define a core wherein the wires are selected to have different dimensions such that the plurality of wires are activated at substantially the same time in response to a temperature change.