Cryogenic Dewar Sensor Cable Routing to Minimize Heat Inleak
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Solution Overview
Problem
Existing temperature monitoring systems for cryogenic dewars introduce significant heat leaks, reducing the holding time of cryogenic temperatures due to the use of electrical cables that are routed through the neck tube, leading to potential damage and thermal intrusion.
Innovation Solution
A cable routing configuration that spirals along the radially outer surface of the neck tube, utilizing small diameter cables routed through radial flanges and sealed apertures to minimize direct heat leakage, with options for sensor placement inside or outside the inner vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical cables are routed through the neck tube to monitor temperature, then temperature monitoring capability is improved, but heat leak into the dewar increases significantly
Solution Approach 1:
The patent introduces an intermediary structure (the flange with aperture) that allows the cable to pass through the dewar wall without directly traversing the thermal path through the neck tube. This mediator enables temperature monitoring while阻断ing the direct heat conduction path, resolving the contradiction between measurement capability and thermal isolation.
Solution Approach 2:
Instead of routing the cable through the longitudinal path of the neck tube (one dimension), the patent routes the cable through the radial flange structure (another dimension). This dimensional change allows the cable to enter the dewar laterally, avoiding the primary thermal conduction path and reducing heat leak while maintaining monitoring capability.
2Measurement precision
If electrical cables are routed through the neck tube, then temperature monitoring is enabled, but cable damage risk increases due to thermal stress
Solution Approach 1:
The flange structure acts as a thermal intermediary, allowing the cable to pass through a region with more moderate thermal gradients compared to the direct neck tube path. This protects the cable from extreme thermal stress while still enabling it to reach the monitoring position inside the dewar.
Solution Approach 2:
The patent design anticipates thermal stress effects on the cable by routing it through a path (radial flange) that provides thermal cushioning. The flange structure absorbs and distributes thermal stresses before they reach the cable, preventing premature cable failure.
3Measurement precision
If cables are routed through the neck tube, then temperature monitoring is achieved, but holding time of cryogenic temperatures is reduced
Solution Approach 1:
The flange aperture serves as a thermal intermediary that minimizes the thermal bridge effect. By passing the cable through this localized aperture rather than along the entire neck tube length, the thermal intrusion is confined to a small region, preserving the overall cryogenic holding time while enabling monitoring.
Solution Approach 2:
The patent applies minimal necessary cable intrusion through the flange aperture rather than allowing excessive cable length inside the dewar. This partial action approach reduces the thermal mass and conductive path length, thereby minimizing heat leak and preserving holding time while still achieving monitoring objectives.
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
Significantly reduces heat inleak, protecting the cables from damage and extending the duration of refrigerant hold time in the dewar by minimizing thermal intrusion.
Implementation Method 1
The cable can be routed through a radial flange of the neck tube assembly or a fitting coupled to a vessel of the dewar... Significantly reduces heat inleak, protecting the cables from damage and extending the duration of refrigerant hold time in the dewar by minimizing thermal intrusion.
Data Source
AI summary
A dewar can comprise a cable routing configuration for a temperature sensor. The cable routing configuration can be disposed through a radial flange of a neck tube assembly or a fitting coupled to an outer vessel of the dewar. The cable routing configuration can be further disposed through a second radial flange into a cavity defined by an inner vessel or through a second fitting coupled to an inner vessel. The temperature sensor can be coupled to an external surface of the inner vessel or an inner surface of the inner vessel.