Heat Pipe Cryocooler Coupling for Faster Low-Temperature Cool-Down
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Solution Overview
Problem
Mechanical refrigerators are inefficient in cooling large thermal masses to low temperatures due to their low cooling power at low temperatures, making them unsuitable for applications like high-field superconducting magnets, where the thermal mass increases with higher magnetic fields.
Innovation Solution
Incorporating a heat pipe that connects the higher temperature stage of a mechanical refrigerator to a lower temperature stage or directly to the target apparatus, allowing the higher cooling power of the first stage to be transferred to the second stage or cooled member, thereby enhancing cooling efficiency and reducing the cool-down time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical refrigerators are used to cool large thermal masses to low temperatures, then the cooling apparatus can operate without liquid cryogens, but the cool-down time becomes significantly longer due to low cooling power at low temperatures
Solution Approach 1:
A heat pipe is introduced as an intermediary component between the first stage and second stage of the mechanical refrigerator. The heat pipe contains a condensable gaseous coolant that transfers cooling power from the first stage to the second stage through phase change, enabling the first stage to assist in cooling the second stage and reducing overall cool-down time
Solution Approach 2:
The heat pipe utilizes phase transitions of a condensable gaseous coolant (evaporation and condensation) to transfer thermal energy from the first stage to the second stage. The coolant evaporates at the first stage where temperature is higher and condenses at the second stage where temperature is lower, efficiently transferring cooling power
2Strength
If the thermal mass of superconducting magnets is increased to achieve higher magnetic fields, then the magnetic field strength improves, but the cooling power requirement increases making mechanical refrigerators less effective
Solution Approach 1:
The cooling capacities of both stages of the mechanical refrigerator are merged to cool the second stage and target apparatus. The heat pipe enables the first stage, which has higher cooling power, to contribute to cooling the second stage, effectively combining the cooling power of both stages to handle larger thermal masses of high-field superconducting magnets
3Loss of time
If liquid cryogens are used for rapid cooling, then the cool-down time is reduced, but the apparatus becomes bulky, complicated and expensive
Solution Approach 1:
The heat pipe serves as a compact intermediary device that enables rapid cooling by transferring thermal energy efficiently between stages. This eliminates the need for bulky liquid cryogen storage and handling apparatus while maintaining rapid cool-down performance through the phase change mechanism of the gaseous coolant
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 significantly improves the cooling performance of mechanical refrigerators by utilizing the higher cooling power of the first stage to accelerate the cooling of the second stage or target apparatus, reducing the cool-down time and making mechanical refrigerators more suitable for applications previously not feasible.
Implementation Method 1
the temperature of the first stage causes the coolant in the first part to condense, whereby the cooled member is cooled by the movement of the condensed liquid from the first part to the second part of the heat pipe
Implementation Method 2
a heat pipe having a first part coupled thermally to the first stage of the mechanical refrigerator and a second part coupled thermally to a cooled member
Implementation Method 3
the second cooled stage being adapted to be coupled thermally with target apparatus to be cooled
Data Source
AI summary
Cooling apparatus is provided which comprises a mechanical refrigerator and a heat pipe. The mechanical refrigerator has a first cooled stage and a second cooled stage, the second cooled stage being adapted to be coupled thermally with target apparatus to be cooled. The heat pipe has a first part coupled thermally to the first stage of the mechanical refrigerator and a second part coupled thermally to a cooled member which may comprise the second stage of the mechanical refrigerator. The heat pipe is adapted to contain a condensable gaseous coolant when in use. An example coolant is Krypton. The apparatus is operated in a first cooling mode in which the temperature of the cooled member causes the coolant within the second part of the heat pipe to be gaseous and the temperature of the first stage causes the coolant in the first part to condense, whereby the cooled member is cooled by the movement of the condensed liquid from the first part to the second part of the heat pipe. When the cooled member is the second stage of the mechanical refrigerator, the heat pipe provides heat between the higher and lower temperature cooled stages during cooling. An associated method of operating such apparatus is also described.