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Title: Design and Testing of a Micro Thermal Conductivity Detector (TCD) System

Abstract

This work describes the design, simulation, fabrication and characterization of a microfabricated thermal conductivity detector to be used as an extension of the {micro}ChemLab{trademark}. The device geometry was optimized by simulating the heat transfer in the device, utilizing a boundary element algorithm. In particular it is shown that within microfabrication constraints, a micro-TCD optimized for sensitivity can be readily calculated. Two flow patterns were proposed and were subsequently fabricated into nine-promising geometries. The microfabricated detector consists of a slender metal film, supported by a suspended thin dielectric film over a pyramidal or trapezoidal silicon channel. It was demonstrated that the perpendicular flow, where the gas directly impinges on the membrane, creates a device that is 3 times more sensitive than the parallel flow, where the gas passed over the membrane. This resulted in validation of the functionality of a microfabricated TCD as a trace-level detector, utilizing low power. the detector shows a consistent linear response to concentration and they are easily able to detect 100-ppm levels of CO in He. Comparison of noise levels for this analysis indicates that sub part per million (ppm) levels are achievable with the selection of the right set of conditions for the detector tomore » operate under. This detector was originally proposed as part of a high-speed detection system for the petrochemical gas industry. This system was to be utilized as a process monitor to detect reactor ''upset'' conditions before a run away condition could occur (faster than current full-scale monitoring systems were able to achieve). Further outlining of requirements indicated that the detection levels likely achievable with a TCD detector would not be sufficient to meet the process condition needs. Therefore the designed and fabricated detector was integrated into a detection system to showcase some technologies that could further the development of components for the current gas phase {micro}ChemLab as well as future modifications for process monitoring work such as: pressurized connections, gas sampling procedures, and packed columns. Component integration of a microfabricated planar pre-concentrator, gas-chromatograph column and TCD in the separation/detection of hydrocarbons, such as benzene, toluene and xylene (BTX) was also demonstrated with this system.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
809627
Report Number(s):
SAND2003-0954
TRN: US200307%%726
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Mar 2003
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; 36 MATERIALS SCIENCE; BENZENE; DESIGN; DIELECTRIC MATERIALS; FABRICATION; GEOMETRY; HEAT TRANSFER; HYDROCARBONS; PETROCHEMICALS; SILICON; TESTING; THERMAL CONDUCTIVITY; TOLUENE; VALIDATION; XYLENES

Citation Formats

SHOWALTER, STEVEN K, CRUZ, DOLORES, GELBARD, FRED, MANGINELL, RONALD P, ADKINS, DOUGLAS R, KOTTENSTETTE, RICHARD, RAWLINSON, KIM S, DULLECK, JR, GEORGE R, HORSCHEL, DANIEL S, and EINFELD, WAYNE. Design and Testing of a Micro Thermal Conductivity Detector (TCD) System. United States: N. p., 2003. Web. doi:10.2172/809627.
SHOWALTER, STEVEN K, CRUZ, DOLORES, GELBARD, FRED, MANGINELL, RONALD P, ADKINS, DOUGLAS R, KOTTENSTETTE, RICHARD, RAWLINSON, KIM S, DULLECK, JR, GEORGE R, HORSCHEL, DANIEL S, & EINFELD, WAYNE. Design and Testing of a Micro Thermal Conductivity Detector (TCD) System. United States. doi:10.2172/809627.
SHOWALTER, STEVEN K, CRUZ, DOLORES, GELBARD, FRED, MANGINELL, RONALD P, ADKINS, DOUGLAS R, KOTTENSTETTE, RICHARD, RAWLINSON, KIM S, DULLECK, JR, GEORGE R, HORSCHEL, DANIEL S, and EINFELD, WAYNE. Sat . "Design and Testing of a Micro Thermal Conductivity Detector (TCD) System". United States. doi:10.2172/809627. https://www.osti.gov/servlets/purl/809627.
@article{osti_809627,
title = {Design and Testing of a Micro Thermal Conductivity Detector (TCD) System},
author = {SHOWALTER, STEVEN K and CRUZ, DOLORES and GELBARD, FRED and MANGINELL, RONALD P and ADKINS, DOUGLAS R and KOTTENSTETTE, RICHARD and RAWLINSON, KIM S and DULLECK, JR, GEORGE R and HORSCHEL, DANIEL S and EINFELD, WAYNE},
abstractNote = {This work describes the design, simulation, fabrication and characterization of a microfabricated thermal conductivity detector to be used as an extension of the {micro}ChemLab{trademark}. The device geometry was optimized by simulating the heat transfer in the device, utilizing a boundary element algorithm. In particular it is shown that within microfabrication constraints, a micro-TCD optimized for sensitivity can be readily calculated. Two flow patterns were proposed and were subsequently fabricated into nine-promising geometries. The microfabricated detector consists of a slender metal film, supported by a suspended thin dielectric film over a pyramidal or trapezoidal silicon channel. It was demonstrated that the perpendicular flow, where the gas directly impinges on the membrane, creates a device that is 3 times more sensitive than the parallel flow, where the gas passed over the membrane. This resulted in validation of the functionality of a microfabricated TCD as a trace-level detector, utilizing low power. the detector shows a consistent linear response to concentration and they are easily able to detect 100-ppm levels of CO in He. Comparison of noise levels for this analysis indicates that sub part per million (ppm) levels are achievable with the selection of the right set of conditions for the detector to operate under. This detector was originally proposed as part of a high-speed detection system for the petrochemical gas industry. This system was to be utilized as a process monitor to detect reactor ''upset'' conditions before a run away condition could occur (faster than current full-scale monitoring systems were able to achieve). Further outlining of requirements indicated that the detection levels likely achievable with a TCD detector would not be sufficient to meet the process condition needs. Therefore the designed and fabricated detector was integrated into a detection system to showcase some technologies that could further the development of components for the current gas phase {micro}ChemLab as well as future modifications for process monitoring work such as: pressurized connections, gas sampling procedures, and packed columns. Component integration of a microfabricated planar pre-concentrator, gas-chromatograph column and TCD in the separation/detection of hydrocarbons, such as benzene, toluene and xylene (BTX) was also demonstrated with this system.},
doi = {10.2172/809627},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2003},
month = {3}
}

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