Dual-Layer Cryogenic Insulation for Propellant Tanks
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Solution Overview
Problem
Current thermal insulation for cryogenic tanks is not optimized for mechanical and thermal performance across all phases of use, particularly in partial or secondary vacuum conditions during flight, leading to significant propellant evaporation and weight penalties.
Innovation Solution
A dual-layer insulation system combining a closed-cell substrate with an open-cell foam layer, treated for gas permeability and water resistance, to leverage vacuum conditions for enhanced thermal performance while maintaining mechanical integrity and minimizing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional closed-cell foam insulation is used, then mechanical strength is maintained, but thermal performance in vacuum conditions deteriorates due to gas trapped in cells
Solution Approach 1:
The insulation system is divided into two distinct layers: a closed-cell foam substrate layer and an open-cell foam layer. This segmentation allows each layer to perform its specific function - the closed-cell layer provides structural support and initial thermal barrier, while the open-cell layer delivers superior thermal performance in vacuum conditions by allowing gas evacuation.
Solution Approach 2:
The patent combines two different foam materials with complementary properties - closed-cell foam for mechanical strength and gas retention, and open-cell foam for thermal insulation in vacuum. This composite structure achieves optimal balance between mechanical integrity and thermal performance across different flight phases.
2Loss of energy
If insulation thickness is increased to improve thermal performance, then propellant protection improves, but launcher payload capacity deteriorates due to added mass
Solution Approach 1:
The patent changes the physical structure parameter of the foam from closed-cell to open-cell configuration. This parameter change allows the insulation to adapt its thermal conductivity based on environmental pressure conditions, achieving superior performance in vacuum without requiring increased thickness or mass.
Solution Approach 2:
The open-cell foam structure dynamically responds to pressure changes during flight. During ascent and ballistic phases in vacuum, the open cells allow gas evacuation, creating optimal thermal insulation. The system adapts its behavior based on environmental conditions rather than requiring static optimization for all phases.
3Loss of energy
If open-cell foam is used for thermal performance, then thermal conductivity improves in vacuum, but water resistance deteriorates allowing condensation damage
Solution Approach 1:
The insulation system segments the thermal protection function between two layers with different properties. The closed-cell substrate layer provides water and condensation resistance, while the open-cell foam layer provides superior thermal performance in vacuum. This functional segmentation resolves the contradiction between water resistance and thermal efficiency.
Solution Approach 2:
The closed-cell foam substrate acts as an intermediary protective layer between the external environment and the open-cell foam. It prevents water and condensation from reaching the open-cell layer while allowing the open-cell layer to maintain its superior thermal insulation properties in vacuum conditions.
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 configuration achieves a 1000% gain in thermal conductivity reduction, significantly reducing propellant loss and payload mass, with a 45% reduction in thermal protection mass and 74% decrease in propellant evaporation during ballistic phases.
Implementation Method 1
the opening of the cells to the outside guaranteeing the drainage of the included gas leaving the atmosphere and therefore thermal conductivity. much smaller, and much lower than that of the substrate layer with closed cells
Implementation Method 2
it is lower than the condensation temperature of the air. The role of the first closed-cell foam layer, through its gas-tight property, is to prevent air from coming into contact with the cold wall
Implementation Method 3
a treatment in the form of impregnation giving the layer of insulating material to the open cells a seal against liquid water while maintaining gas permeability
Data Source
AI summary
The insulation article according to the invention comprises, on a substrate layer deposited on the structure to be protected (tank wall), a second layer of open-cell material that can drain the gas it contains during ascent and thus offers higher thermal insulation characteristics than the substrate material, which has the advantage of preventing air from reaching the tank wall. A treatment can be applied to the open-cell material, rendering it liquid-tight but gas-permeable, in order to keep the open-cell material dry without compromising drainage. This application is particularly relevant to propellant tanks for space launch vehicles.