A dryer for rapid response on-line expired gas measurements

1979 ◽  
Vol 46 (6) ◽  
pp. 1196-1199
Author(s):  
N. S. Deno ◽  
E. Kamon
Keyword(s):  
Water Vapor ◽  
Gas Analysis ◽  
Dew Point ◽  
Step Response ◽  
Gas Sampling ◽  
Vapor Partial Pressure ◽  
On Line ◽  
Gas Measurements ◽  
Time Required ◽  
Sampling Flow

A dryer is described for use in on-line breath-by-breath gas analysis systems. The dryer continuously removes water vapor by condensation and controls the sample gas at 2 degrees C dew-point temperature or 5 Torr water vapor partial pressure. It is designed to operate at gas sampling flow rates from 0.5 to 1 1.min-1. The step-response time for the described system including a Beckman LB-2 CO2 analyzer, sampling tubing, and dryer is 120 ms at 1 l.min-1. The time required for gas samples to transport through the dryer is 105 ms at a gas sampling-flow rate of 1 l.min=1.

scholarly journals Gas measurements as a mean for identification of Partial Discharges in XLPE HV cable insulation

2017 ◽  
Author(s):  
Patrick Janus ◽  
Hans Edin ◽  
Kruphalan Tamil Selva
Keyword(s):  
Gas Analysis ◽  
Partial Discharges ◽  
Basic Material ◽  
Power Cables ◽  
Cable Insulation ◽  
Large Coupling ◽  
Safety Issues ◽  
On Line ◽  
Surface Discharges ◽  
Gas Measurements

<p>Partial Discharges (PD) on high-voltage alternating current (HVAC) cables insulated with cross-linked polyethylene (XLPE) has a low occurrence, but consequences are usually severe since PD ultimately results in cable failures. Up until now the only efficient way to monitor HVAC cables for PD has been to install large coupling devices which are able to measure PDs directly from the power cables in order to verify if they are fault-free. These installations, usually of a temporary nature, are troublesome for several reasons like safety issues, measurement uncertainty, labor intensity etc. <br />For the purpose to ultimately create a system that is able to be utilized for PD Detection by means of gas analysis, which is easily applicable in on site, on-line conditions, initial experiments were performed in order to investigate basic material properties of XLPE and to investigate the performance of tin oxide (SnO2) sensors for such an application. For this purpose a specialized test cell was developed in order to be able to investigate different conditions which can be expected in a cable insulation system.<br />It was found from the experiments that surface discharges are detectable by means of gas analysis and that these gases penetrate an XLPE sample. It was also demonstrated that the SnO2 based sensor system displays a good selectivity to the gases emitted by PD and remain inert towards other gases emitted from XLPE samples.</p>

scholarly journals High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air

2012 ◽  
Vol 5 (4) ◽  
pp. 5823-5888 ◽  
Author(s):  
C. W. Rella ◽  
H. Chen ◽  
A. E. Andrews ◽  
A. Filges ◽  
C. Gerbig ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Water Vapor ◽  
Greenhouse Gas ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Dew Point ◽  
Correction Factors ◽  
Gas Streams ◽  
Remote Sites ◽  
Gas Measurements

Abstract. Traditional techniques for measuring the mole fractions of greenhouse gas in the well-mixed atmosphere have required extremely dry sample gas streams (dew point < −25 °C) to achieve the inter-laboratory compatibility goals set forth by the Global Atmospheric Watch program of the World Meteorological Organization (WMO/GAW) for carbon dioxide (±0.1 ppm) and methane (±2 ppb). Drying the sample gas to low levels of water vapor can be expensive, time-consuming, and/or problematic, especially at remote sites where access is difficult. Recent advances in optical measurement techniques, in particular Cavity Ring Down Spectroscopy (CRDS), have led to the development of highly stable and precise greenhouse gas analyzers capable of highly accurate measurements of carbon dioxide, methane, and water vapor. Unlike many older technologies, which can suffer from significant uncorrected interference from water vapor, these instruments permit for the first time accurate and precise greenhouse gas measurements that can meet the WMO/GAW inter-laboratory compatibility goals without drying the sample gas. In this paper, we present laboratory methodology for empirically deriving the water vapor correction factors, and we summarize a series of in-situ validation experiments comparing the measurements in humid gas streams to well-characterized dry-gas measurements. By using the manufacturer-supplied correction factors, the dry-mole fraction measurements have been demonstrated to be well within the GAW compatibility goals up to at least 1% water vapor. By determining the correction factors for individual instruments once at the start of life, this range can be extended to at least 2% over the life of the instrument, and if the correction factors are determined periodically over time, the evidence suggests that this range can be extended above 4%.

scholarly journals A Stochastic Model to Describe the Scattering in the Response of Polysilicon MEMS

2021 ◽  
Vol 2 (1) ◽  
pp. 95
Author(s):  
Luca Dassi ◽  
Marco Merola ◽  
Eleonora Riva ◽  
Angelo Santalucia ◽  
Andrea Venturelli ◽  
...  
Keyword(s):  
Silicon Film ◽  
Micro Fabrication ◽  
Micro Electro Mechanical Systems ◽  
Local Fluctuations ◽  
Stochastic Framework ◽  
On Line ◽  
Chip Testing ◽  
On Chip ◽  
Time Required ◽  
Polycrystalline Silicon Film

The current miniaturization trend in the market of inertial microsystems is leading to movable device parts with sizes comparable to the characteristic length-scale of the polycrystalline silicon film morphology. The relevant output of micro electro-mechanical systems (MEMS) is thus more and more affected by a scattering, induced by features resulting from the micro-fabrication process. We recently proposed an on-chip testing device, specifically designed to enhance the aforementioned scattering in compliance with fabrication constraints. We proved that the experimentally measured scattering cannot be described by allowing only for the morphology-affected mechanical properties of the silicon films, and etch defects must be properly accounted for too. In this work, we discuss a fully stochastic framework allowing for the local fluctuations of the stiffness and of the etch-affected geometry of the silicon film. The provided semi-analytical solution is shown to catch efficiently the measured scattering in the C-V plots collected through the test structure. This approach opens up the possibility to learn on-line specific features of the devices, and to reduce the time required for their calibration.

Monitoring and modelling an industrial trickling filter using on-line off-gas analysis and respirometry

2000 ◽  
Vol 41 (12) ◽  
pp. 139-148 ◽  
Author(s):  
H. Vanhooren ◽  
D. Demey ◽  
I. Vannijvel ◽  
P. A. Vanrolleghem
Keyword(s):  
Phase Equilibrium ◽  
Model Calibration ◽  
Inorganic Carbon ◽  
Diffusion Constant ◽  
Gas Analysis ◽  
Trickling Filter ◽  
Process Characteristics ◽  
Substrate Diffusion ◽  
On Line ◽  
Ph Dependent

The process characteristics of an industrial scale trickling filter plant were quantified by means of a five day intensive measurement campaign with the use of on-line respirometry and on-line off-gas analysis. Respirometry was used to measure the readily biodegradable CODst and the off-gas sensor was used to monitor the O2 and CO2 content of the off-gases. To model the biodegradation in the filters, the model developed by Rauch et al. (1999) was used. It is based on the decoupling of two basic processes in biofilm systems, substrate diffusion and biodegradation. This model was extended with equations for the production and the pH-dependent liquid-phase equilibrium for inorganic carbon (IC). The measured effluent and off-gas concentrations could be followed very closely by the calibrated model. O2 and CO2 measurements revealed that the system was not always oxygen limited. The model calibration thus required the use of a very low value of the diffusion constant for readily biodegradable substrate.

scholarly journals Water vapor total column measurements using the Elodie Archive at Observatoire de Haute Provence from 1994 to 2004

2009 ◽  
Vol 2 (2) ◽  
pp. 1075-1097
Author(s):  
A. Sarkissian ◽  
J. Slusser
Keyword(s):  
Water Vapor ◽  
Water Vapor Absorption ◽  
The Earth ◽  
Vapor Absorption ◽  
On Line ◽  
High Resolution Spectrometer ◽  
Long Term Trend ◽  
Resolution Spectrometer ◽  
Total Column

Abstract. Water vapor total column measurements at Observatoire de Haute Provence (5°42' E, +43°55' N), south of France, were obtained using observations of astronomical objects made between July 1994 and December 2004 on the 193-cm telescope with the high-resolution spectrometer Elodie. Spectra of stars, nebulae, and other astronomical objects were taken regularly during 10 years. More than 18 000 spectra from 400 nm to 680 nm are available on-line in the Elodie Archive. This archive, usually explored by astronomers, contains information to study the atmosphere of the Earth. Water vapor absorption lines appear in the visible in delimited bands that astronomers often avoid for their spectral analysis. We used the Elodie Archive with two objectives: firstly, to retrieve seasonal variability and long-term trend of atmospheric water vapor, and secondly, to remove signatures in spectra for further astronomical or geophysical use. The tools presented here are developed following, when possible, formats and standards recommended by the International Virtual Observatory Alliance.

scholarly journals A kinetic evaluation on no2 formation in the post-flame region of pressurized oxy-combustion process

2020 ◽  
pp. 236-236
Author(s):  
Xuebin Wang ◽  
Gaofeng Dai ◽  
Gregory Yablonsk ◽  
Milan Vujanovic ◽  
Richard Axelbaum
Keyword(s):  
Power Plants ◽  
Combustion Process ◽  
Strong Acid ◽  
Dew Point ◽  
Kinetic Evaluation ◽  
Atmospheric Air ◽  
Energy Penalty ◽  
Flame Region ◽  
No2 Formation ◽  
Time Required

Pressurized oxy-combustion is a promising technology that can significantly reduce the energy penalty associated with first generation oxy-combustion for CO2 capture in coal-fired power plants. However, higher pressure enhances the production of strong acid gases, including NO2 and SO3, aggravating the corrosion threat during flue gas recirculation. In the flame region, high temperature NOx exists mainly as NO, while conversion from NO to NO2 happened in post-flame region. In this study, the conversion of NO ? NO2 has been kinetically evaluated under representative post-flame conditions of pressurized oxy-combustion after validating the mechanism (80 species and 464 reactions), which includes nitrogen and sulfur chemistry based on GRI-Mech 3.0. The effects of residence time, temperature, pressure, major species (O2/H2O), and minor or trace species (CO/SOx) on NO2 formation are studied. The calculation results show that when pressure is increased from 1 to 15 bar, NO2 is increased from 1 to 60 ppm, and the acid dew point increases by over 80?C. Higher pressure and temperature greatly reduce the time required to reach equilibrium, e.g., at 15 bar and 1300?C, equilibrium is reached in 1 millisecond and the NO2/NO is about 0.8%. The formation and destruction of NO2 is generally through the reversible reactions: NO+O+M=NO2+M, HO2+NO=NO2+OH, and NO+O2=NO2+O. With increasing pressure and decreasing temperature, O plays a much more important role than HO2 in the oxidation of NO. A higher water vapor content accelerates NO2 formation in all cases by providing more O and HO2 radicals. The addition of CO or SO2 also promotes the formation of NO2. Finally, NO2 formation in a Pressurized oxy-combustion furnace is compared with that in a practical atmospheric air-combustion furnace and the comparison show that NO2 formation in a Pressurized oxy-combustion furnace can be over 10 times that of an atmospheric air-combustion furnace.

An Evaluation of the Kenz Calorie Counter during Progressive Treadmill Exercise in Adults and Children

1996 ◽  
Vol 8 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Nicholas J. Walters ◽  
David A. Brodie
Keyword(s):  
Linear Regression ◽  
Energy Expenditure ◽  
Body Mass ◽  
Correction Factor ◽  
Treadmill Exercise ◽  
Gas Analysis ◽  
Age Group ◽  
Measured Energy ◽  
Adults And Children ◽  
On Line

The purpose of this study was to assess the validity of data derived from the Kenz calorie counter during progressive, incremental treadmill exercise. Direct comparisons were made with calories calculated from on-line gas analysis. The subjects were 18 adults, 18 postadolescent children, and 24 preadolescent children. Linear regression (r2 > .95) showed a progressive deviation away from a 1:1 relationship between Kenz data and V̇O2 data with increasing age of subject which remained when standardized to kcal · kg−1 body mass or kcal · m−2 · hour−1. The Kenz calorie counter, after applying an age group correction factor, can thus be used as a suitable analog for measured energy expenditure.

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