NMR Sample Tube Temperature Control via Nested Bypass Channels
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Solution Overview
Problem
Conventional temperature control devices for NMR sample tubes suffer from high temperature gradients and limited temperature control performance due to high flow resistance and deflections in the fluid flow, which can lead to inadequate temperature control and risk of sample tube damage.
Innovation Solution
A temperature control device employing a countercurrent principle with a bypass flow that allows at least 50% of the total fluid flow to exit through an axial end of the outermost or next inner flow channel, reducing flow resistance and enhancing temperature control performance while maintaining low temperature gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional temperature control devices use simple fluid flow around the sample tube, then the device structure is simple, but the temperature gradient is high and temperature control performance is limited
Solution Approach 1:
The fluid flow path is segmented into multiple nested flow channels (outermost flow channel, inner flow channels) with alternating flow directions. This segmentation allows different portions of the fluid flow to serve different functions: the outermost channel provides a bypass flow that reduces overall flow resistance, while inner channels provide counterflow that maintains low temperature gradients at the sample tube.
Solution Approach 2:
Multiple flow channels are nested concentrically around the sample tube, with each inner flow channel surrounded by an outer flow channel. This nested arrangement maximizes the heat exchange surface area between the fluid and the sample tube while maintaining a compact device structure. The flow channels are arranged in the radial direction, creating multiple concentric rings of fluid flow.
2Temperature
If the fluid flow is guided through multiple deflections and narrow passages directly at the sample tube, then the temperature control is improved, but the flow resistance increases and the fluid flow is limited
Solution Approach 1:
The bypass flow path is extracted from the main counterflow path by providing a separate outermost flow channel that allows fluid to bypass the narrow passages and multiple deflections of the inner flow channels. This extracted bypass path reduces the overall flow resistance while the inner channels continue to provide temperature control through counterflow.
Solution Approach 2:
The outermost flow channel provides an excessive bypass flow that does not directly contact the sample tube but still contributes to temperature control by pre-conditioning the fluid and reducing pressure losses. This partial flow path handles a significant portion of the total fluid flow (at least 50%), reducing the burden on the inner flow channels.
3Temperature
If high fluid pressure is used to improve temperature control performance, then the temperature control is enhanced, but the sample tube may be pushed out and damaged
Solution Approach 1:
The fluid flow is segmented into a bypass component and a counterflow component. The bypass flow through the outermost channel handles the pressure load, while the counterflow in inner channels provides temperature control. This segmentation allows high temperature control performance without requiring excessive pressure that could damage the sample tube.
Solution Approach 2:
The outermost flow channel acts as an intermediary that decouples the pressure transmission from the temperature control function. By providing a separate bypass path, it mediates between the high-pressure fluid supply and the sample tube, preventing direct transmission of damaging pressures while still enabling effective temperature control through the combined flow paths.
4Temperature
If the fluid flow path is extended to provide sufficient cooling/heating, then the temperature control is improved, but the device length increases
Solution Approach 1:
Multiple flow channels are nested concentrically in the radial direction rather than extending in the axial direction. This nested arrangement provides extended heat exchange path length within a compact axial footprint, effectively increasing temperature control capability without increasing device length.
Solution Approach 2:
The fluid flow path is transitioned from a primarily axial arrangement to a radial arrangement with nested concentric channels. This dimensional change allows the flow to traverse multiple radii (outermost to inner channels) within a compact axial space, providing sufficient heat exchange length without extending the device length significantly.
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 achieves high temperature control performance with low axial temperature gradients, preventing sample tube damage and ensuring uniform temperature across the active volume, even under high pressure conditions.
Implementation Method 1
The walls between the flow channels and the interior work as heat exchangers, so that the temperature gradient in the fluid flow is noticeably reduced directly at the sample tube
Implementation Method 2
In a counterflow area adjacent flow channels are each connected to one another with a fluid passage at an axial end such that the direction of flow of a fluid flow in the flow channels of the Counterflow area reverses
Implementation Method 3
a plurality of nested, concentric flow channels for temperature-controlling fluid, which run coaxially to the interior space, are formed around a cylindrical interior space for receiving the NMR sample tube
Data Source
Figure 1a
Figure 1b~1c
Figure 2a
AI summary
The temperature control unit (20) has multiple concentric flow channels (28,31) for temperature controlled fluid, which are designed around a cylindrical internal space (21) for incorporation of the nuclear magnetic resonance-test-test tube (22). The flow channels are running coaxial to inner space and are meshed. One of the flow channels, particularly the outermost flow channel of the temperature control unit or the next inner flow channel of the temperature control unit has a fluid outlet (35) at an axial end. An independent claim is also included for a temperature control method for a nuclear magnetic resonance-test tube.