scholarly journals Environmental Monitoring of Methane with Quartz-Enhanced Photoacoustic Spectroscopy Exploiting an Electronic Hygrometer to Compensate the H2O Influence on the Sensor Signal

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2935 ◽  
Author(s):  
Arianna Elefante ◽  
Giansergio Menduni ◽  
Hubert Rossmadl ◽  
Verena Mackowiak ◽  
Marilena Giglio ◽  
...  
Keyword(s):  
Water Vapor ◽  
Environmental Monitoring ◽  
Photoacoustic Spectroscopy ◽  
Simultaneous Detection ◽  
Vapor Concentration ◽  
Interband Cascade Laser ◽  
Qepas Signal ◽  
Monitoring Applications ◽  
Ch4 Concentration ◽  
Qepas Sensor

A dual-gas sensor based on the combination of a quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor and an electronic hygrometer was realized for the simultaneous detection of methane (CH4) and water vapor (H2O) in air. The QEPAS sensor employed an interband cascade laser operating at 3.34 μm capable of targeting a CH4 absorption line at 2988.8 cm−1 and a water line at 2988.6 cm−1. Water vapor was measured with both the electronic hygrometer and the QEPAS sensor for comparison. The measurement accuracy provided by the hygrometer enabled the adjustment of methane QEPAS signal with respect to the water vapor concentration to retrieve the actual CH4 concentration. The sensor was tested by performing prolonged measurements of CH4 and H2O over 60 h to demonstrate the effectiveness of this approach for environmental monitoring applications.

scholarly journals Fiber-Coupled Quartz-Enhanced Photoacoustic Spectroscopy System for Methane and Ethane Monitoring in the Near-Infrared Spectral Range

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5607
Author(s):  
Giansergio Menduni ◽  
Fabrizio Sgobba ◽  
Stefano Dello Russo ◽  
Ada Cristina Ranieri ◽  
Angelo Sampaolo ◽  
...  
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Near Infrared ◽  
Integration Time ◽  
Vapor Concentration ◽  
Acoustic Detection ◽  
Near Ir ◽  
Qepas Signal ◽  
Infrared Spectral ◽  
Lock In ◽  
Minimum Detection Limits

We report on a fiber-coupled, quartz-enhanced photoacoustic spectroscopy (QEPAS) near-IR sensor for sequential detection of methane (CH4 or C1) and ethane (C2H6 or C2) in air. With the aim of developing a lightweight, compact, low-power-consumption sensor suitable for unmanned aerial vehicles (UAVs)-empowered environmental monitoring, an all-fiber configuration was designed and realized. Two laser diodes emitting at 1653.7 nm and 1684 nm for CH4 and C2H6 detection, respectively, were fiber-combined and fiber-coupled to the collimator port of the acoustic detection module. No cross talk between methane and ethane QEPAS signal was observed, and the related peak signals were well resolved. The QEPAS sensor was calibrated using gas samples generated from certified concentrations of 1% CH4 in N2 and 1% C2H6 in N2. At a lock-in integration time of 100 ms, minimum detection limits of 0.76 ppm and 34 ppm for methane and ethane were achieved, respectively. The relaxation rate of CH4 in standard air has been investigated considering the effects of H2O, N2 and O2 molecules. No influence on the CH4 QEPAS signal is expected when the water vapor concentration level present in air varies in the range 0.6–3%.

A quartz-enhanced photoacoustic spectroscopy sensor for measurement of water vapor concentration in the air

2015 ◽  
Vol 24 (1) ◽  
pp. 014206 ◽  
Author(s):  
Ping Gong ◽  
Liang Xie ◽  
Xiao-Qiong Qi ◽  
Rui Wang ◽  
Hui Wang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Photoacoustic Spectroscopy ◽  
Vapor Concentration ◽  
Water Vapor Concentration

scholarly journals Numerical Simulation of the Water Vapor Separation of a Moisture-Selective Hollow-Fiber Membrane for the Application in Wood Drying Processes

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 593
Author(s):  
Nasim Alikhani ◽  
Douglas W. Bousfield ◽  
Jinwu Wang ◽  
Ling Li ◽  
Mehdi Tajvidi
Keyword(s):  
Water Vapor ◽  
Constant Temperature ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Vacuum Pressure ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Fiber Membrane ◽  
Wood Drying ◽  
Air Velocity

In this study, a simplified two-dimensional axisymmetric finite element analysis (FEA) model was developed, using COMSOL Multiphysics® software, to simulate the water vapor separation in a moisture-selective hollow-fiber membrane for the application of air dehumidification in wood drying processes. The membrane material was dense polydimethylsiloxane (PDMS). A single hollow fiber membrane was modelled. The mass and momentum transfer equations were simultaneously solved to compute the water vapor concentration profile in the single hollow fiber membrane. A water vapor removal experiment was conducted by using a lab-scale PDMS hollow fiber membrane module operated at constant temperature of 35 °C. Three operation parameters of air flow rate, vacuum pressure, and initial relative humidity (RH) were set at different levels. The final RH of dehydrated air was collected and converted to water vapor concentration to validate simulated results. The simulated results were fairly consistent with the experimental data. Both experimental and simulated results revealed that the water vapor removal efficiency of the membrane system was affected by air velocity and vacuum pressure. A high water vapor removal performance was achieved at a slow air velocity and high vacuum pressure. Subsequently, the correlation of Sherwood (Sh)–Reynolds (Re)–Schmidt (Sc) numbers of the PDMS membrane was established using the validated model, which is applicable at a constant temperature of 35 °C and vacuum pressure of 77.9 kPa. This study delivers an insight into the mass transport in the moisture-selective dense PDMS hollow fiber membrane-based air dehumidification process, with the aims of providing a useful reference to the scale-up design, process optimization and module development using hollow fiber membrane materials.

Simultaneous detection of ammonia, methane and ethylene at 1.63 μm with diode laser photoacoustic spectroscopy

2005 ◽  
Vol 82 (3) ◽  
pp. 495-500 ◽  
Author(s):  
M. Scotoni ◽  
A. Rossi ◽  
D. Bassi ◽  
R. Buffa ◽  
S. Iannotta ◽  
...  
Keyword(s):  
Diode Laser ◽  
Photoacoustic Spectroscopy ◽  
Simultaneous Detection ◽  
Laser Photoacoustic Spectroscopy

Degradation of Solid Oxide Fuel Cell Cathodes Accelerated at a High Water Vapor Concentration

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
S. H. Kim ◽  
K. B. Shim ◽  
C. S. Kim ◽  
J. T. Chou ◽  
T. Oshima ◽  
...  
Keyword(s):  
Water Vapor ◽  
Voltage Drop ◽  
Cell Voltage ◽  
High Water ◽  
Solid Oxide ◽  
Constant Current ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Oxide Fuel ◽  
Constant Current Density

The influence of water vapor in air on power generation characteristic of solid oxide fuel cells was analyzed by measuring cell voltage at a constant current density, as a function of water vapor concentration at 800°C and 1000°C. Cell voltage change was negligible at 1000°C, while considerable voltage drop was observed at 800°C accelerated at high water vapor concentrations of 20 wt % and 40 wt %. It is considered that La2O3 formed on the (La0.8Sr0.2)0.98MnO3 surface, which is assumed to be the reason for a large voltage drop.

scholarly journals A Coated Spherical Microresonator for Measurement of Water Vapor Concentration at PPM Levels in Very Low Humidity Environments

2018 ◽  
Vol 36 (13) ◽  
pp. 2667-2674 ◽  
Author(s):  
Arun Kumar Mallik ◽  
Gerald Farrell ◽  
Dejun Liu ◽  
Vishnu Kavungal ◽  
Qiang Wu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Low Humidity
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