Capillary Thermal Modulator for Narrow GC Reinjection Pulses
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Solution Overview
Problem
Existing chromatography systems face challenges in achieving narrow reinjections at fast heating and low temperatures without high operating expenses or sufficient cooling power, particularly with consumable-free modulators like thermoelectric coolers.
Innovation Solution
A thermal modulator system using a capillary surrounded by a heating member and thermal buffer, with a cold finger and auxiliary heater, allows for rapid heating and cooling of the capillary to achieve narrow reinjections by minimizing thermal load on the cooling device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If liquid nitrogen cooling systems are used to achieve cryogenic temperatures for narrow reinjections, then trapping performance is improved, but operating expenses increase and commercial practicality decreases
Solution Approach 1:
The patent changes the temperature parameter from cryogenic (liquid nitrogen) to moderate temperatures achievable by thermoelectric coolers. The thermal buffer material and geometry are optimized to enable effective trapping at these elevated temperatures, resolving the contradiction between trapping performance and operating cost
Solution Approach 2:
The patent replaces expensive consumable liquid nitrogen with a reusable thermoelectric cooler system. The thermal buffer acts as a thermal reservoir that can be repeatedly charged and discharged without consumable replacement, eliminating ongoing operating expenses while maintaining narrow reinjection capability
2Use of energy by stationary object
If thermoelectric coolers are used instead of liquid nitrogen, then operating cost decreases, but cooling power and ability to achieve cryogenic temperatures is insufficient
Solution Approach 1:
The thermal buffer is pre-cooled to a low temperature before the trapping event. This preliminary cooling stores thermal energy in the buffer, which then provides the necessary cooling power during the rapid trapping phase, compensating for the limited instantaneous cooling capacity of the thermoelectric cooler
Solution Approach 2:
The thermal buffer acts as a thermal cushion that absorbs and releases heat as needed. By pre-charging the buffer with cooling capacity, the system cushions against the limited power of the thermoelectric cooler, enabling sufficient cooling power for narrow reinjections without requiring the cooler to continuously operate at high power
3Speed
If fast heating is achieved through resistive heating or hot gas jets, then heating speed increases, but thermal load on cooling device increases and modulation speed decreases
Solution Approach 1:
The thermal management function is segmented between the heating element, thermal buffer, and cooling device. The thermal buffer acts as an independent thermal mass that mediates between the fast heating and the cooling device, allowing rapid heating without directly increasing the cooling load, thus enabling fast modulation
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
The system efficiently achieves narrow reinjections with fast modulation and reduced cooling power requirements, suitable for chromatographic systems like GCxGC, by alternating temperatures in the capillary to trap and desorb analytes effectively.
Implementation Method 1
resistive heating of metal capillary columns
Implementation Method 2
cooling the capillary to a second temperature that is sufficient to trap and focus the analytes in the capillary
Implementation Method 3
reduce thermal transfer between the cooling device and the capillary during the first time period
Implementation Method 4
increase the thermal transfer between the cooling device and the capillary via the cold finger during the second time period
Data Source
Figure 1A
Figure 1B~1C
Figure 2A
AI summary
This disclosure relates a device for a chromatographic system, comprising: a chamber defining an internal portion, a capillary disposed within the chamber, the capillary having an input, an output, and an elongate body extending between the input and the output, a cold finger having a first portion in thermal contact with a portion of the elongate body to define a capillary trapping zone, wherein the first portion of the cold finger extends to a second portion that is situated external to the chamber, a heater in thermal contact with the trapping zone of the capillary and configured to transfer heat to the trapping zone, a thermal buffer configured to buffer the heat from the heater into the cold finger and thereby retain the heat within the trapping zone of the capillary, a cooling device arranged external to the chamber and thermally connected to the second portion of the cold finger to define a primary conduction zone, wherein the cooling device is configured to generate a cooling temperature zone at the primary conduction zone, a controller configured to selectively alternate the trapping zone between a cooling temperature by turning off the heat and using the cooling device together with its engagement with the cold finger, and an injection temperature using the heater, wherein the heater alternates between an off state and an on state and a user defined frequency.