Thermally Modulated Variable Restrictors for Chromatography Pressure Control
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Solution Overview
Problem
Current chromatography systems, particularly those using supercritical fluid chromatography, face challenges in maintaining independent control over mobile phase flow rate and system pressure, especially in capillary-scale or open tubular columns, due to the introduction of significant dead volume by back pressure regulators and susceptibility to plugging in heated variable linear restrictors.
Innovation Solution
The development of thermally modulated variable restrictors with a short decompression distance and a heating element that applies heat to a subsection of the fluidic channel, allowing for independent control of system pressure and mobile phase linear velocity without introducing significant dead volume, and featuring a replaceable restrictor tip to prevent plugging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If back pressure regulators are used to independently control mobile phase flow rate and system pressure, then independent control is achieved, but significant dead volume is introduced to the chromatographic system
Solution Approach 1:
The patent extracts the pressure control function from a separate back pressure regulator component and integrates it directly into the restrictor tip structure. The restrictor tip itself becomes the pressure control element through thermal modulation, eliminating the need for a separate BPR component and its associated dead volume.
Solution Approach 2:
The patent merges the flow restriction function and pressure control function into a single integrated component (the restrictor tip). By combining these functions, the system eliminates the dead volume associated with separate BPR components while maintaining independent control capability.
2Ease of operation
If heated variable linear restrictors are used to control linear velocity, then flow rate control is achieved, but the restrictor becomes susceptible to plugging due to analyte precipitation
Solution Approach 1:
The patent applies heating locally only to a specific section of the restrictor body rather than heating the entire restrictor. This localized heating maintains analyte solubility in the critical region where pressure depression occurs, preventing precipitation and plugging while still achieving flow control.
Solution Approach 2:
The patent applies heat before the mobile phase fully depressurizes, maintaining analyte solubility during the critical transition period. This preliminary heating action prevents analyte precipitation before it can occur, thereby preventing plugging.
3Volume of stationary object
If fixed restrictors are used in capillary-scale separations, then dead volume is minimized, but independent control of flow rate and system pressure is not enabled
Solution Approach 1:
The patent transforms the fixed restrictor into a dynamic, thermally modulated restrictor. By applying thermal energy to the restrictor body, the system can dynamically adjust the mobile phase properties and maintain independent control of flow rate and pressure while keeping the restrictor geometry fixed and small.
Solution Approach 2:
The patent changes physical parameters (temperature, density) of the mobile phase through thermal modulation of the restrictor body, enabling independent control of flow rate and pressure without changing the restrictor geometry or introducing dead volume.
4Use of energy by moving object
If short region heated restrictors with small ID are used, then energy transfer efficiency is improved, but very high temperatures (approximately 600°C) are required for moderate pressure changes
Solution Approach 1:
The patent applies heating to a specific section of the restrictor body with optimized dimensions, creating a localized thermal zone that efficiently transfers energy to the mobile phase. This localized heating approach achieves effective temperature control at moderate temperatures rather than requiring extreme temperatures.
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 enables precise control over mobile phase flow and pressure across a wide range of chromatography systems, maintaining analyte solubility and preventing plugging, while allowing for efficient operation at lower temperatures and reducing the need for frequent replacement of the restrictor.
Implementation Method 1
A heating element applies heat to a subsection of the fluidic channel
Implementation Method 2
thermally modulated variable restrictors...heating element applies heat to a subsection of the fluidic channel...independent control of system pressure and mobile phase linear velocity
Data Source
AI summary
Thermally modulated variable restrictors used in chromatography systems enable independent control of system pressure and linear velocity of a compressible mobile phase passing through a chromatography column. A method for configuring a chromatography system with independent control of system pressure and mass flow rate of a compressible mobile phase includes determining a type of chromatography separation column to be used in the chromatography system, matching a thermally modulated variable restrictor to the type of chromatography separation column for use together during operation of the chromatography system, and bundling the chromatography column with its matching thermally modulated variable restrictor for distribution as a single package.