NMR Probe Fluid Cooling via Preliminary Heat Exchanger Action
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Solution Overview
Problem
Nuclear magnetic resonance (NMR) analysis systems face a trade-off between rotation frequency of the sample holder and operating temperature, where increasing the flow rate to enhance measurement precision raises the equilibrium temperature, limiting the ability to achieve both high rotation frequencies and low operating temperatures simultaneously.
Innovation Solution
A method involving an initial cooling step to lower the heat exchanger temperature and adjust the fluid flow rate to a lower initial rate, followed by increasing the flow rate to achieve a high rotation frequency, allowing the temperature to drop below its equilibrium value before stabilizing, utilizing a heat exchanger and potentially a heating module to maintain a stable thermal plateau at a low temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the flow rate of the fluid intended for the probe is increased to enhance measurement precision and rotation frequency, then the rotation frequency is improved, but the equilibrium temperature of the flow increases
Solution Approach 1:
The heat exchanger is cooled down to a preliminary temperature below the desired equilibrium temperature before the fluid flow is activated. This preliminary cooling action allows the system to achieve both high rotation frequency and low temperature simultaneously, as the heat exchanger is already in a cold state ready to receive the fluid flow without causing temperature rise
Solution Approach 2:
The heat exchanger acts as an intermediary thermal storage medium that decouples the relationship between fluid flow rate and temperature. By storing cold energy in the heat exchanger structure before fluid flow begins, it mediates between the high flow rate requirement for rotation and the low temperature requirement for NMR analysis
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
Enables both low temperatures and high rotation frequencies, improving NMR analysis by stabilizing the temperature and reducing oscillations, allowing for precise measurements across a range of temperatures.
Implementation Method 1
a heat exchange between the flow intended for the probe and a flow of a cooling fluid, called 'cryogenic flow', within a heat exchanger, in order to cool the flow intended for the probe
Data Source
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AI summary
The process includes an initial cooling step (E0) in which the temperature (T_ECH) of the heat exchanger (30) is lowered, and, simultaneously, the flow rate of the first stream (FLs) is set to an initial flow rate. Following the initial cooling step (E0), a circulation operation (E1) of the first stream (FLs) is initiated, in which the first stream (FLs) passes through a heat exchanger (30) with a first flow rate that is greater than the initial flow rate. The initial flow rate of the first stream can be set to zero or to a suitable value such that the pressure inside the circuit is greater than or equal to the pressure outside the circuit.