Cold Jet Nozzle Collimator for 2D Gas Chromatography Alignment
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Solution Overview
Problem
The existing two-dimensional gas chromatography modulation systems require precise three-dimensional alignment of cold and hot jets with the loop modulator tube for efficient operation, which is challenging to maintain due to temperature variations and results in uneven cooling and release efficiency, leading to imperfect chromatography separation.
Innovation Solution
A collimator is attached to the cold jet nozzle to modify the flow, reducing the cross-sectional area from a round to a rectangular shape, simplifying alignment to two-dimensional and enhancing cooling and release efficiency by ensuring consistent cooling across a 3.0 mm region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If precise three-dimensional alignment of cold and hot jets with loop modulator tube is implemented, then modulation efficiency is improved, but alignment complexity and difficulty increase
Solution Approach 1:
A collimator is introduced as an intermediary component between the cold jet nozzle and the loop modulator tube. The collimator receives the cold jet flow and redirects it through a specific path that ensures proper alignment with the modulator tube, eliminating the need for direct precise alignment between the cold jet nozzle and tube. This mediator component simplifies the alignment procedure while maintaining modulation efficiency.
Solution Approach 2:
The alignment function is segmented into two independent parts: the collimator alignment (which is simplified and more tolerant) and the modulator tube alignment (which remains precise but is now relative to the collimator rather than the cold jet nozzle). This segmentation allows each component to be aligned independently, reducing overall alignment complexity.
2Area of stationary object
If cold jet flow is allowed to expand freely into open space, then cooling coverage area increases, but cooling efficiency becomes uneven
Solution Approach 1:
The collimator creates a localized region of controlled cold jet flow by providing a defined passage with specific geometry (e.g., angled walls or a channel). Within this localized region, the cold jet maintains consistent velocity and temperature distribution, ensuring uniform cooling efficiency across the entire cooling coverage area. The local structure of the collimator compensates for the natural expansion that would otherwise cause non-uniformity.
3Measurement precision
If alignment tolerance is reduced for better separation, then separation precision improves, but alignment difficulty increases
Solution Approach 1:
The collimator performs a preliminary alignment function by pre-positioning and pre-directing the cold jet flow along a controlled path toward the loop modulator tube. This preliminary action ensures that the cold jet is already properly oriented and positioned before it reaches the critical interaction region with the modulator tube, thereby achieving high separation precision while allowing for easier initial alignment of the collimator itself.
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 modification improves the reliability and efficiency of the modulation process by allowing flexible alignment, maintaining consistent cooling efficiency and complete hot jet release, even with temperature variations, thus ensuring successful comprehensive two-dimensional gas chromatography separation.
Implementation Method 1
A collimator is attached to the cold jet nozzle to modify the flow, reducing the cross-sectional area from a round to a rectangular shape
Implementation Method 2
The cold jet subassembly consists of a steel tube... cold jet flow through the tube will further spread out due to free expansion when it passes into the open space below the cold jet
Implementation Method 3
The hot jet subassembly is mounted at right angles to the cold jet... the hot jet is the best focused to blow hot gas to release the trapped material
Implementation Method 4
The space between the inner and outer tubes is evacuated with a mechanical roughing pump and valved off, thereby forming a vacuum insulated housing around the cold jet. Vacuum insulation is essential for the introduction to the GC oven of a cryogenically cooled gas stream
Data Source
AI summary
A collimator fixed to the cold jet nozzle of a modulator of a two-dimensional gas chromatograph to aid in the alignment of the cold jet nozzle and loop modulator tube.