Superconducting Magnet Conduction Cooling via Thermal Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conduction cooling of superconducting magnets is inefficient due to the use of stainless steel as a heat transfer path, which has low thermal conductivity, and thermal contraction differences between materials, leading to reduced contact area and slower cooling rates, especially when using resin-wound coils.
Innovation Solution
Incorporating a heat conducting member with a higher thermal contraction rate than the winding portion, such as a flange made of pure metal, to maintain thermal contact from normal to low temperatures, and using a thermal contraction difference absorbent material to absorb thermal expansion differences between the winding core and flange, ensuring continuous contact and improved heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If stainless steel is used as the heat transfer path connecting the bobbin and the winding portion, then the structural strength is maintained, but the thermal conductivity is low resulting in slow cooling speed
Solution Approach 1:
A heat transfer member made of high thermal conductivity material (pure aluminum or oxygen-free copper) is introduced as an intermediary between the stainless steel bobbin and the winding portion. This mediator component provides a dedicated high-efficiency thermal conduction path that bypasses the limitation of stainless steel's low thermal conductivity, enabling rapid heat removal from the superconducting winding while the bobbin maintains its structural function.
2Speed
If the contact area between the bobbin and the winding portion is increased to improve cooling speed, then the thermal contact is improved, but the thermal contraction difference between resin and metal causes gap formation at low temperatures
Solution Approach 1:
The thermal contraction characteristics of the system are modified by changing the material composition of the bobbin. By incorporating a metal component with thermal contraction rate matching the resin winding portion, the system maintains consistent contact pressure and thermal contact area across the temperature range from room temperature to cryogenic operating conditions, ensuring reliable heat transfer without gap formation.
3Speed
If liquid helium immersion cooling is used, then the cooling efficiency is high, but the consumption of liquid helium resource increases
Solution Approach 1:
A heat transfer member serves as an intermediary that couples the superconducting winding to an external chiller system, replacing the need for liquid helium immersion. This mediator enables efficient conductive heat transfer from the winding to the chiller, achieving effective cooling through solid-to-solid thermal contact rather than liquid-to-solid convection, thereby eliminating liquid helium consumption.
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 allows for quicker cooling of the superconducting magnet by maintaining direct thermal contact and reducing thermal resistance, enhancing cooling efficiency and reducing the need for liquid helium.
Implementation Method 1
a heat conducting member for thermally connecting the coil portion and the cooling device
Implementation Method 2
at least one of the first flange, the second flange, and the winding core has a region made of a material whose thermal contraction rate is larger than a thermal contraction rate of the winding portion
Implementation Method 3
a cooling device for cooling the coil portion
Implementation Method 4
When the superconducting wire is cooled to have a certain temperature or less peculiar to a superconducting material, a current can flow through the superconducting wire with no resistance
Implementation Method 5
conduction cooling in which a chiller and a bobbin in which a coil is provided are connected by a heat transfer member made of a good heat conductor such as pure aluminum or oxygen-free copper and a superconducting magnet is cooled by the chiller via the heat transfer member
Data Source
AI summary
A superconducting magnet in which efficiency of conduction cooling is improved is described as well as a magnetic resonance imaging apparatus that includes the superconducting magnet and requires no liquid helium. The magnet resonance imaging apparatus includes: a coil portion including a winding core, a winding portion formed by winding a wire around the winding core, a first flange provided on one side of the winding core, and a second flange provided on the other side of the winding core; a cooling device for cooling the coil portion; and a heat conducting member for thermally connecting the coil portion and the cooling device, in which at least one of the first flange, the second flange, and the winding core has a region made of a material whose thermal contraction rate is larger than a thermal contraction rate of the winding portion.