Nested Conduit Layout for Hydrogen Vaporization Without Fluid Freezing
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Solution Overview
Problem
Existing heat exchangers are inefficient in quickly transitioning liquid hydrogen from 20 K to gaseous hydrogen at 320 K, leading to freezing of the heat transfer fluid, which compromises heat transfer.
Innovation Solution
A conduit design with an inner and outer tube arrangement, where the inner tube defines an annular space with the outer tube, allowing phase transition of the working fluid in the inner tube before further warming, and a base plate configuration with spaced tubesheets to minimize heat transfer to the heat transfer fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical heat transfer fluid such as EGW6040 is used to evaporate liquid hydrogen, then heat transfer efficiency is improved, but the heat transfer fluid freezes at around 250 K compromising heat transfer
Solution Approach 1:
The conduit is divided into two separate passages: an inner passage for the working fluid and an outer annular passage for the heat transfer fluid. This segmentation allows independent control of fluid paths and thermal interactions, enabling the working fluid to undergo phase transition in the inner passage while the heat transfer fluid flows in the outer passage without freezing.
Solution Approach 2:
The inner tube containing the working fluid passage is nested within the outer tube that contains the heat transfer fluid passage. This nested arrangement maximizes thermal contact area while maintaining separate fluid paths, allowing efficient heat transfer from the heat transfer fluid to the working fluid without direct mixing or thermal equilibrium between the two fluids.
2Productivity
If materials with high thermal conductivity are used to build base plates and tubes, then heat can be quickly transferred, but phase transition requires a lot thermal energy causing heat transfer fluid to freeze
Solution Approach 1:
High thermal conductivity materials are used selectively in the conduit walls and base plates where rapid heat transfer is needed for vaporization, while the flow configuration ensures that the heat transfer fluid does not lose excessive heat. The annular passage design provides sufficient surface area for heat transfer without requiring the heat transfer fluid to give up all its thermal energy, preventing freezing while maintaining high vaporization speed.
3Reliability
If the inner outlet opens in the outer passage, then gaseous working fluid fills the annular space limiting heat transfer from phase transition, but this limits heat transfer fluid freezing
Solution Approach 1:
The working fluid undergoes phase transition (evaporation) completely within the inner passage before exiting through the inner outlet into the annular space. This preliminary completion of phase transition prevents subsequent freezing of the heat transfer fluid in the outer passage, as the most demanding thermal energy requirement is satisfied before the fluids interact in the annular space.
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
Ensures reliable and efficient heat transfer by limiting freezing of the heat transfer fluid, ensuring effective vaporization of hydrogen from liquid to gas without compromising the heat exchanger's performance.
Implementation Method 1
heat transfer resulting from phase transition to the heat transfer fluid and thus limits the risks of heat transfer fluid freezing
Implementation Method 2
phase transition of the working fluid from liquid to gas requires a lot thermal energy
Implementation Method 3
allows most of the phase transition of the working fluid from liquid to gas to happen in the inner tube
Data Source
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AI summary
This conduit (22) for a heat exchanger (16) comprises: - an outer tube (40), comprising an outer inlet (40i) and an outer outlet (40o) and defining an outer passage (40p) configured for guiding a working fluid (W) from the outer inlet (40i) to the outer outlet (40o), and - an inner tube (42), comprising an inner inlet (42i) and an inner outlet (42o) and defining an inner passage (42p) configured for guiding the working fluid (W) from the inner inlet (42i) to the inner outlet (42o), wherein the inner tube (42) is arranged in the outer passage (42p) and defines with the outer tube (40) an annular space (A), the inner outlet (42o) opening in the outer passage (40p)