NMR Probe Thermal Insulation via Radiative Cooling
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Solution Overview
Problem
NMR systems face challenges in maintaining effective thermal insulation at low temperatures while minimizing energy consumption, particularly in preventing condensation and radiation heat influences, which are not adequately addressed by existing methods.
Innovation Solution
The implementation of a thermal insulation device for NMR systems that utilizes high-pressure gas streams cooled by cryogenic fluids, combined with a multi-layer insulation and active thermal protection screens, to efficiently rotate and cool the sample holder while minimizing thermal radiation influence, using a counter-current heat exchanger and vacuum-insulated cryogenic lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional passive insulation (vacuum, multi-layer screens) is used, then thermal radiation losses are reduced, but energy consumption increases due to high heat influx requiring more cooling power
Solution Approach 1:
The patent converts the harmful thermal radiation into a beneficial effect by using radiative cooling. The cold surface of the probe and surrounding components actively emits thermal radiation to reject heat to the environment, turning the previously harmful radiative heat transfer into a useful cooling mechanism that reduces the burden on active cooling systems
Solution Approach 2:
The system uses the probe's own cold surface to actively reject heat through thermal radiation. The cold components themselves become the radiative cooling surfaces, eliminating the need for additional active cooling mechanisms and reducing overall energy consumption while maintaining thermal isolation
2Object-affected harmful factors
If passive thermal isolation is used to protect from thermal radiation, then radiation heat influence is reduced, but condensation risk increases due to temperature differences
Solution Approach 1:
The patent addresses condensation risk by using radiative cooling to actively manage temperature gradients. The cold surfaces emit thermal radiation to maintain controlled temperature differences, preventing the extreme cold spots that would cause atmospheric condensation while still providing thermal isolation from radiation
Solution Approach 2:
The system operates in a controlled atmosphere (vacuum or inert gas) that prevents condensation. By maintaining an inert environment around the cold probe components, the patent eliminates the condensation issue while allowing effective thermal radiation management
3Temperature
If active cooling is increased to compensate for heat influx, then low-temperature operation is maintained, but energy consumption increases significantly
Solution Approach 1:
The patent reduces cooling energy consumption by converting thermal radiation from a heat gain mechanism into a heat rejection mechanism. The cold probe surfaces actively radiate heat to the environment, creating a passive cooling effect that supplements active cooling and significantly reduces the energy required to maintain low temperatures
Solution Approach 2:
The radiative cooling operates continuously as long as the probe surfaces remain cold, providing constant passive heat rejection. This continuous useful action complements the active cooling system, maintaining temperature stability with minimal additional energy input
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 solution achieves significant reduction in energy consumption and thermal radiation losses, allowing for effective low-temperature operation with minimal heat input from the environment, thereby ensuring accurate sample analysis and reducing the risk of equipment degradation.
Implementation Method 1
The three gas streams coming from this first source 1 pass through a cryostat 10, in which they are cooled in one or more heat exchangers 12
Implementation Method 2
This heat exchange between the two fluids is obtained by forced convection between the gas streams 2, 3, 4 and the wall of their respective high-pressure tubes
Implementation Method 3
The probe, the rotation module and its fluidic supply device must be protected from the surrounding thermal radiation at a temperature of approximately 300K
Implementation Method 4
The probe must be isolated from the surrounding atmosphere to protect it from condensation and gas convection to suppress external convective and gas conduction heat inputs
Implementation Method 5
The function of the third flow is to create an aerostatic bearing for supporting the rotor in the stator
Implementation Method 6
The first flow has the function of rotating this sample holder, by acting on the blades or fins of a turbine driving a rotor
Data Source
Figure 1
Figure 2
AI summary
Method for operating a thermal insulation device (100) comprising a screen (101, 102, 103, 104) for insulating a first member (21) and/or a second member (20; 30; 16; 10; 30) from a thermal radiation, the method comprising: a heat-exchange step in which heat is exchanged between a stream of a fluid, notably a gas, and the screen, notably a step of transferring heat from the heat screen to the stream, and a use step in which the stream is used for guiding the first member (21) and/or for driving the movement of the first member and/or for exchanging heat with the first member, notably for cooling the first member.