Insulated Medium Pipes Using HFO Foam and Selective Gas Barriers
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Solution Overview
Problem
Existing thermally insulated pipe systems face issues with gas diffusion and water vapor migration, leading to reduced insulation efficiency and potential damage over time, particularly in systems carrying aqueous media, and existing solutions like metallic and polymeric barrier layers are difficult to manufacture or provide insufficient insulation.
Innovation Solution
The use of hydrofluoroolefins (HFOs) as cell gases in thermal insulation foam, combined with selective polymer barriers, to minimize gas diffusion and allow water vapor escape, while maintaining mechanical stability and insulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic barrier layers are used to prevent gas diffusion, then gas exchange is completely prevented, but water vapor diffusion is also completely blocked causing water accumulation in thermal insulation
Solution Approach 1:
The barrier layer is designed with selective permeability properties, allowing it to differentiate between gas molecules and water vapor molecules. The layer has specific local qualities (molecular size selectivity) that enable it to block larger gas molecules while permitting smaller water vapor molecules to pass through, thus resolving the contradiction between preventing gas exchange and allowing water vapor escape.
Solution Approach 2:
The barrier layer utilizes a porous structure with specific pore sizes that are smaller than gas molecules but larger than water vapor molecules. This porous material allows water vapor to diffuse through while blocking gas molecules, solving the contradiction by using the size-exclusion property of porous materials to achieve selective permeability.
2Object-affected harmful factors
If polymeric barrier layers are used to allow water vapor escape, then gas diffusion is reduced, but insulation properties are insufficient
Solution Approach 1:
The barrier layer is constructed as a composite material combining polymeric materials with gas-blocking additives or multi-layer structures. This composite approach maintains the water vapor permeability of polymers while incorporating components that enhance gas blocking properties, thus achieving both water vapor escape and improved insulation properties simultaneously.
3Reliability
If conventional blowing agents are used in foam insulation, then insulation is provided, but gas diffusion into the foam reduces long-term insulation efficiency
Solution Approach 1:
The invention changes the physical and chemical parameters of the cell gas by using gases with lower thermal conductivity and smaller molecular sizes (such as HFOs with 5-15 carbon atoms). These parameter changes result in gases that diffuse more slowly and have better insulating properties, thereby maintaining insulation efficiency over time despite diffusion occurring.
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
HFOs improve insulation performance, manufacturability, and safety by reducing viscosity, preventing blistering, and enhancing mechanical properties, while allowing controlled gas exchange, thus maintaining long-term insulation efficiency and safety.
Implementation Method 1
HFOs improve insulation performance, manufacturability, and safety by reducing viscosity, preventing blistering, and enhancing mechanical properties
Implementation Method 2
The composition of the cell gases in the foam changes over time. This occurs through the diffusion of nitrogen and oxygen from the environment into the foam and through the diffusion of the foam or cell gases originally contained in the foam
Implementation Method 3
thermal insulation, which in turn is surrounded by a casing... thermally insulated carrier pipes... improved thermal insulation
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a thermally insulated conduit (1) comprising at least one medium pipe (4), at least one thermal insulation layer (3) arranged around the medium pipe, and at least one outer sheath (2) arranged around the thermal insulation layer, wherein the outer sheath (2) optionally comprises a barrier (9) made of plastic, and wherein the thermal insulation (3) comprises a foam whose cell gas contains at least 10 vol% HFOs. Such a conduit exhibits good insulation properties, a good environmental footprint, and is easy to manufacture.