Cryogenic Transfer Line Optical Shield for Vacuum and Thermal Isolation
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Solution Overview
Problem
Cryogenic fluid transfer lines face inefficiencies in creating a vacuum and maintaining thermal performance due to slowed pumping caused by pressure drops and conductance limitations in the insulation layers, leading to incomplete pressure levels in certain areas despite high pumping capacities.
Innovation Solution
Incorporating an optical shield made of heat-conducting materials like copper or aluminum, positioned to intercept direct heat radiation and facilitate gas pumping, while being thermally connected to the heat shield and tubes, enhances the conductance and thermal performance by creating a privileged path for pumped gas and reducing heat ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pumping opening is provided in the outer casing to create vacuum, then vacuum creation is enabled, but direct heat radiation from the outer casing to the inner tubes occurs through the opening
Solution Approach 1:
An optical shield is introduced as an intermediary element between the pumping opening and the inner tubes. This shield intercepts direct heat radiation paths while allowing the pumping operation to proceed through the opening, thus mediating between the conflicting requirements of vacuum creation and heat radiation prevention.
Solution Approach 2:
The optical shield is positioned specifically at the pumping opening area where heat radiation is most problematic. By applying the shielding function locally at this critical position rather than throughout the entire system, the solution addresses the specific heat radiation issue at the opening while maintaining vacuum pumping capability.
2Loss of energy
If a thermal screen with insulation layers is used to reduce heat transfer, then thermal insulation is improved, but gas pumping efficiency is reduced due to pressure drops and conductance limitations
Solution Approach 1:
The thermal management system is segmented into distinct functional zones: the optical shield at the pumping opening for radiation blocking, the multi-layer insulation in the intermediate region for heat transfer reduction, and the vacuum space for pumping. This segmentation allows each zone to optimize its specific function without compromising the others.
Solution Approach 2:
The optical shield is positioned in a plane separate from the thermal screen, creating a three-dimensional arrangement where radiation blocking and thermal insulation functions operate in different spatial dimensions. This dimensional separation allows both functions to coexist without interfering with gas pumping pathways.
3Object-affected harmful factors
If the optical shield is positioned close to the inner tubes to block radiation, then heat radiation prevention is improved, but the space for gas pumping and vacuum creation is reduced
Solution Approach 1:
The optical shield is nested within the overall vacuum insulation structure, positioned in the annular space between the outer casing and the inner tubes. This nesting arrangement allows the shield to occupy the available space efficiently without encroaching on the inner tube volume or significantly reducing the gas pumping 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
This configuration improves the efficiency of vacuum creation and thermal performance by ensuring effective gas pumping and minimizing heat radiation, thereby achieving better thermal insulation and pressure levels throughout the cryogenic fluid transfer line.
Implementation Method 1
to prevent or limit direct heat radiation from the outer casing to the inner tubes
Implementation Method 2
The optical shield comprises a plate of heat-conducting material, in particular a metal, copper or aluminum and said plate is thermalized
Implementation Method 3
the optical cover is cooled by contact and conduction with the heat shield via at least one connecting braid made of heat-conducting material
Data Source
Figure 1~3
AI summary
Cryogenic fluid transfer line comprising a tubular outer jacket (2) housing at least two interior fluid-transfer tubes (3) and a heat shield (4) forming an insulating wall arranged around the interior tubes (3), the outer jacket (2) comprising a lateral pumping opening (5) connected to a pumping member (6) intended to pull a vacuum in the outer jacket (2), characterized in that the heat shield (4) comprises an orifice (14) situated adjacent to the opening (5) and an optical cover (7), the optical cover (7) being positioned facing the orifice (14) and in a plane distinct from that of the wall of the heat shield (4) so as to prevent or limit direct thermal radiation from the outer jacket (2) toward the interior tubes (3).