Flexible Radiative Fin With Self-Deployment for Spacecraft Cooling

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Solution Overview

Problem

Current deployable radiators for satellites are complex, costly, and heavy due to the need for mechanical actuation and 2-phase heat transport systems, which are not adaptable to the increasing demand for efficient cooling in smaller, constellation-based satellites with variable heat rejection needs.

Innovation Solution

A flexible radiative fin using pyrolytic graphite sheets and a heat emission layer, self-deploying without mechanical actuators, utilizing the torque of a flexible rod for deployment and folding, and integrated with solar array wings for activation, simplifying design and reducing weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional deployable radiators with mechanical actuators and 2-phase heat transport systems are used, then heat rejection capability is maximized, but device complexity, weight, and cost increase significantly

Engineering Contradiction:
Improveheat rejection capabilityVSAvoidmechanical actuation system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes mechanical actuators and complex 2-phase heat transport systems from the radiator structure, retaining only the essential heat rejection function through a simplified single-phase heat pipe system integrated directly into the flexible laminate structure

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The flexible radiative fin uses its own flexibility and elastic memory to automatically deploy and retract without external mechanical actuators, and uses integrated heat pipes to self-transport heat from the satellite body to the radiative surface

Inventive Principle:
Principle #25Self-service

2Strength

If rigid metallic sandwich panels with honeycomb structure are used for deployable radiators, then structural strength and heat rejection are improved, but weight and device complexity increase

Engineering Contradiction:
Improvestructural strengthVSAvoidradiator weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces rigid metallic sandwich panels with a flexible radiative laminate structure consisting of thin layers (support layer, heat conductive layer, heat emission layer) that can bend and deploy without requiring heavy internal honeycomb structures

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The radiator uses a composite laminate structure combining different materials (support layer material, heat conductive material, heat emission material) to achieve both structural integrity and thermal performance in a lightweight flexible form

Inventive Principle:
Principle #40Composite materials

3Power

If 2-phase heat transport systems with large diameter pipes are used, then heat transport capacity is maximized, but weight and device complexity increase due to thick walls and high pressure requirements

Engineering Contradiction:
Improveheat transport capacityVSAvoidpiping weight
Core Design Contradiction:
PowerVSWeight of moving object

Solution Approach 1:

The patent replaces complex 2-phase heat transport systems with high-pressure pipes and mechanical actuators with a simpler single-phase heat pipe system that uses capillary action and phase change within the heat pipe structure itself for heat transport

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The heat pipe system is integrated directly into the flexible radiative laminate structure, merging the heat transport function with the radiative surface structure rather than using separate heavy piping systems

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If deployable radiators are designed for maximal cooling capacity, then heat rejection is improved, but the radiator becomes heavier and more costly

Engineering Contradiction:
Improvecooling capacityVSAvoidadaptability to variable heat rejection demands
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a dynamically adaptable radiator that can adjust its deployed area based on thermal demands through the flexible nature of the laminate and controlled deployment/retraction mechanisms, allowing the same structure to serve different cooling requirements

Inventive Principle:
Principle #15Dynamics

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 flexible radiative fin provides efficient heat dissipation, is cheaper and lighter, and offers adaptable cooling capacity without the need for complex mechanical systems, suitable for satellites with varying thermal demands.

Implementation Method 1

a flexible radiative laminate (20), said flexible radiative laminate comprising at least one pyrolytic graphite sheet (21) serving as a heat transporting layer

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

at least one heat emission layer (22), in contact with one pyrolytic graphite sheet (21) and preferably adhered to the latter by a layer of adhesive material (23)

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

a flexible rod (30), which extends from the end fitting (10) on a side of the radiative laminate (20)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3925894B1A flexible radiative fin for a spacecraft
Publication Date: 2022.08.03 AIRBUS DEFENCE & SPACE SAS
  • EP3925894B1 patent drawingFigure 1
  • EP3925894B1 patent drawingFigure 2a~2b
  • EP3925894B1 patent drawingFigure 3~4

AI summary

The invention proposes a radiative fin (1) for a spacecraft, comprising: - an end fitting (10) of heat conductive material, adapted to be mounted on the spacecraft, - a flexible radiative laminate (20), connected to the end fitting at one end and having an opposite free end, and comprising : ∘ at least one pyrolytic graphite sheet, and ∘ at least one heat emission layer in contact with the pyrolythic graphite sheet on at least part of the surface of the pyrolythic graphite sheet, and - a flexible rod (30), extending from the end fitting (10) along at least part of a side of the flexible radiative laminate (20) and being affixed to the latter, wherein the flexible rod (30) is adapted to occupy a folded position and a deployed position and to exert, while in the folded position, a deployment torque adapted to bring the flexible rod back to the deployed position.