Functionally graded structures, methods, and systems for thermal management

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Solution Overview

Problem

Solid-state cooling systems face inefficiencies due to nonuniform phase transformation of thermoelastic materials across temperature gradients, leading to incomplete utilization and reduced overall efficiency.

Innovation Solution

A functionally graded structure with varying transformation temperatures or cross-sectional areas is fabricated using shape memory alloys, optimized through additive manufacturing, to promote near-uniform phase transformation across the structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform mechanical load is applied across the elastocaloric material, then the structure is simple to manufacture, but the phase transformation becomes nonuniform due to temperature gradient, reducing cooling efficiency

Engineering Contradiction:

Improveuniform mechanical load applicationVSAvoidcooling efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies local quality by creating a functionally graded structure where the cross-sectional area varies along the length of the elastocaloric material. Specifically, the cross-sectional area is smaller at regions experiencing higher temperatures and larger at regions experiencing lower temperatures. This geometric gradient compensates for the temperature-dependent transformation stress, ensuring uniform phase transformation across the entire material despite the temperature gradient, thereby maintaining high cooling efficiency while preserving manufacturing simplicity.

Inventive Principle:

Principle #3Local quality

2Productivity

If the cross-sectional area is varied to achieve uniform phase transformation, then cooling efficiency improves, but the manufacturing complexity increases

Engineering Contradiction:

Improvecooling efficiencyVSAvoidfunctionally graded structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs parameter changes by systematically varying the cross-sectional area parameter along the length of the elastocaloric material according to a predetermined gradient. This controlled geometric parameter variation is designed to compensate for the temperature gradient effects, ensuring that the stress required for phase transformation remains uniform across different temperature zones. The gradual parameter change approach balances the need for improved cooling efficiency with manageable manufacturing complexity.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If segments at higher temperatures undergo incomplete phase transformation, then the device structure remains simple, but the overall caloric output diminishes

Engineering Contradiction:

Improveuniform stress distributionVSAvoidcaloric output

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The patent addresses the incomplete phase transformation issue by implementing local quality through a functionally graded cross-sectional area. The cross-section is specifically designed to be larger at higher temperature regions where transformation stress requirements are greater, and smaller at lower temperature regions. This local geometric adjustment ensures that sufficient stress is delivered to all segments regardless of their temperature, achieving complete phase transformation throughout the material and maximizing overall caloric output while maintaining relatively simple device architecture.

Inventive Principle:

Principle #3Local quality

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

Enhances the coefficient of performance (COP) and specific cooling power (SCP) by ensuring uniform phase transformation, improving the efficiency of solid-state refrigeration systems.

Implementation Method 1

the critical stress required to initiate and complete martensitic transformation increases with temperature

Methodology Applied

Scientific EffectMartensitic transformation: Phase Change

Implementation Method 2

elastocaloric materials (eCMs) have attracted significant attention due to their substantial latent heat typically exceeding 30 J/g as well as their mechanical tunability

Methodology Applied

Scientific EffectElastocaloric effect: Mechanocaloric Effect