Vacuum-Insulated Transfer Line for Leak-Tight Cryogenic Refueling

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Solution Overview

Problem

Existing transfer systems for cryogenic fluids, such as liquid hydrogen, face challenges with leakiness and inability to handle temperature sensitivity, particularly in refueling aircraft, due to conventional swivel joints and single-walled tubes.

Innovation Solution

A transfer line arrangement using flexible sections of multiwalled corrugated tubes with gimbal protection and vacuum insulation, combined with rigid sections and movable support structures, ensuring leak-tightness and flexibility for handling distance and height differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional swivel joints are used in transfer lines, then flexibility and pivotable movement are achieved, but leak-tightness deteriorates and wear increases

Engineering Contradiction:

ImproveflexibilityVSAvoidleak-tightness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent removes the swivel joint component entirely from the transfer line system. Instead of using traditional mechanical swivel joints, the invention employs a flexible hose assembly that provides the necessary flexibility and pivotable movement through its inherent flexibility, thereby eliminating the leakage and wear problems associated with conventional swivel joints while maintaining adaptability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical swivel joint system with a flexible hose assembly that relies on material flexibility rather than mechanical articulation. This substitution eliminates the complex mechanical components that cause leakage and wear, providing a simpler, more reliable solution that maintains the required flexibility for positioning.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If single wall tubes are used for transferring liquid hydrogen, then simplicity and low cost are achieved, but temperature sensitivity and boil-off losses worsen

Engineering Contradiction:

ImprovesimplicityVSAvoidboil-off losses

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent employs a multi-layer composite hose assembly consisting of an inner tube, intermediate layer, and outer cover. This composite structure provides thermal insulation to reduce boil-off losses of liquid hydrogen while maintaining flexibility and simplicity of installation. The layered construction combines materials with different properties to achieve both thermal protection and operational simplicity.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If flexible hose assemblies are used instead of rigid transfer lines, then adaptability to distance and height differences improves, but weight and handling difficulty worsen

Engineering Contradiction:

ImproveadaptabilityVSAvoidweight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent uses a flexible hose assembly with a multi-layer construction including an inner tube, intermediate layer, and outer cover. This flexible shell design provides the necessary adaptability to accommodate various distances and height differences during refueling operations while keeping the overall weight manageable through optimized material selection and layer thickness.

Inventive Principle:

Principle #30Flexible shells and thin films

4Loss of energy

If vacuum insulated multiwalled tubes are used, then thermal insulation and reduction of boil-off losses improve, but device complexity and manufacturing cost worsen

Engineering Contradiction:

Improveboil-off lossesVSAvoidcomplexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent implements a multi-layer composite hose assembly where the intermediate layer provides vacuum insulation. This composite structure reduces thermal transfer and minimizes boil-off losses of cryogenic liquids while maintaining flexibility. The integrated multi-layer design achieves thermal insulation without requiring separate complex insulation systems.

Inventive Principle:

Principle #40Composite materials

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 solution provides a leak-tight and flexible system capable of transferring temperature-sensitive fluids like liquid hydrogen efficiently, reducing boil-off losses and explosion hazards, while being easier to handle and maintain.

Implementation Method 1

The transfer line comprises vacuum insulated multiwalled tubes

Methodology Applied

Scientific EffectVacuum insulation: Vacuum

Implementation Method 2

vacuum insulated multiwalled tubes permit to transfer also temperature sensitive fluids

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP4711660A1Transfer line arrangement

Publication Date: 2026.03.18 NEXANS SA

Figure 1
Figure 2A~3

AI summary

A transfer line arrangement (200) comprises a transfer line (201, 220) for fluids and a support structure (116, 117, 118) attached to the transfer line. The transfer line comprises flexible sections (202) enabling pivotable movement of the transfer line around an axis such that one end of the transfer line is connectable to a connector at a fluid source (107) for a fluid and the other end of the transfer line is connectable with a connector (111) at a tank to be filled with fluid. The transfer line comprises vacuum insulated multiwalled tubes.