Cryogenic Adsorption Refrigerator Two-Chamber Evaporator Design
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Solution Overview
Problem
Cryogenic adsorption refrigerators face issues with superfluid helium coolant loss, prolonged pre-cooling times, and reduced cooling capacity due to narrow apertures designed to restrict superfluid flow, which also impede gaseous coolant flow and induce pressure oscillations.
Innovation Solution
The refrigerator is designed with two evaporation chambers separated by a flow control aperture, allowing gaseous coolant to flow freely while restricting superfluid flow, reducing pre-cooling time, and minimizing pressure oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a narrow aperture is provided in the fluid flow conduit to restrict superfluid coolant flow, then the hold time of the device is increased, but the flow rate of gaseous coolant is reduced and pressure oscillations are induced
Solution Approach 1:
The evaporator is divided into two separate chambers (first evaporation chamber and second evaporation chamber) with the flow control aperture located between them. This segmentation allows the aperture to restrict superfluid flow from the second chamber while the first chamber maintains unrestricted gaseous coolant flow to the adsorption pump, thereby preserving cooling capacity while extending hold time.
2Loss of substance
If a narrow aperture is provided to reduce superfluid flow, then coolant loss is reduced, but gaseous coolant flow is impeded and heat transfer increases
Solution Approach 1:
By segmenting the evaporator into two chambers with the aperture positioned between them, the system restricts superfluid flow (reducing coolant loss) while maintaining a clear, unobstructed path for gaseous coolant from the first chamber to the adsorption pump. This prevents pressure oscillations and minimizes heat transfer through the coolant column.
3Reliability
If the device is pre-cooled from room temperature to operating temperature, then the device can begin to operate effectively, but this process takes several days
Solution Approach 1:
The two-chamber evaporator design with the flow control aperture enables more efficient heat transfer during pre-cooling by allowing gaseous coolant to flow freely from the first chamber to the adsorption pump without restriction. This maintains higher coolant flow rates during the pre-cooling phase, reducing the time required to reach operating temperature while still providing superfluid flow restriction during normal operation.
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 design extends the operational time, reduces pre-cooling time from days to hours, and enhances thermal performance by maintaining gaseous coolant flow and reducing heat transfer, thus improving overall cooling capacity.
Implementation Method 1
an adsorbent material, such as activated charcoal or a mineral zeolite, is located in a first chamber
Implementation Method 2
Adsorption refrigerators use the latent heat of evaporation of a liquid to produce a cooling effect
Implementation Method 3
the temperature of the coolant falls below the lambda point for the coolant, the coolant becomes superfluid
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Disclosed herein is a cryogenic adsorption refrigerator for cooling a thermal load, the cryogenic adsorption refrigerator comprising: an adsorption pump comprising a chamber containing an adsorbent material; an evaporator arranged to contain coolant; and one or more fluid flow conduits. The evaporator comprises a first evaporation chamber and a second evaporation chamber. The first evaporation chamber is fluidly connected with the adsorption pump via the one or more fluid flow conduits such that gaseous coolant can flow from the first evaporation chamber to the adsorption pump. The first evaporation chamber and the second evaporation chamber are fluidly connected via a flow control aperture arranged to restrict the flow of superfluid coolant from the second evaporation chamber to the first evaporation chamber.