scholarly journals Modelling of effects of water vapor and temperature gradient on moisture and gas transfer in unsaturated landfill cover

2021 ◽  
Vol 9 (8) ◽  
pp. 380-386
Author(s):  
Liang Tong Zhan ◽  
Song Feng ◽  
Tao Wu ◽  
Ping Chen
Keyword(s):  
Water Vapor ◽  
Temperature Gradient ◽  
Gas Transfer ◽  
Landfill Cover

scholarly journals Eddy flux measurements of sulfur dioxide deposition to the sea surface

2018 ◽  
Vol 18 (20) ◽  
pp. 15291-15305 ◽  
Author(s):  
Jack G. Porter ◽  
Warren De Bruyn ◽  
Eric S. Saltzman
Keyword(s):  
Water Vapor ◽  
Sulfur Dioxide ◽  
Molecular Diffusion ◽  
Trace Gases ◽  
Sea Surface ◽  
Negative Ion ◽  
Gas Transfer ◽  
Ionization Mass ◽  
Sensible Heat ◽  
Flux Measurements

Abstract. Deposition to the sea surface is a major atmospheric loss pathway for many important trace gases, such as sulfur dioxide (SO2). The air–sea transfer of SO2 is controlled entirely on the atmospheric side of the air–sea interface due to high effective solubility and other physical–chemical properties. There have been few direct field measurements of such fluxes due to the challenges associated with making fast-response measurements of highly soluble trace gases at very low ambient levels. In this study, we report direct eddy covariance air–sea flux measurements of SO2, sensible heat, water vapor, and momentum. The measurements were made over shallow coastal waters from the Scripps Pier, La Jolla, CA, using negative ion chemical ionization mass spectrometry as the SO2 sensor. The observed transfer velocities for SO2, sensible heat, water vapor, and momentum and their wind speed dependences indicate that SO2 fluxes can be reliably measured using this approach. As expected, the transfer velocities for SO2, sensible heat, and water vapor are lower than that for momentum, demonstrating the contribution of molecular diffusion to the overall air-side resistance to gas transfer. Furthermore, transfer velocities of SO2 were lower than those of sensible heat and water vapor when observed simultaneously. This result is attributed to diffusive resistance in the interfacial layer of the air–sea interface.

scholarly journals Temperature profiling of the atmospheric boundary layer with rotational Raman lidar during the HD(CP)<sup>2</sup> Observational Prototype Experiment

2015 ◽  
Vol 15 (5) ◽  
pp. 2867-2881 ◽  
Author(s):  
E. Hammann ◽  
A. Behrendt ◽  
F. Le Mounier ◽  
V. Wulfmeyer
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Temperature Gradient ◽  
Atmospheric Boundary Layer ◽  
Average Power ◽  
Mixing Ratio ◽  
Raman Lidar ◽  
Backscatter Signal ◽  
Low Background ◽  
Water Vapor Mixing Ratio

Abstract. The temperature measurements of the rotational Raman lidar of the University of Hohenheim (UHOH RRL) during the High Definition of Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observation Prototype Experiment (HOPE) in April and May 2013 are discussed. The lidar consists of a frequency-tripled Nd:YAG laser at 355 nm with 10 W average power at 50 Hz, a two-mirror scanner, a 40 cm receiving telescope, and a highly efficient polychromator with cascading interference filters for separating four signals: the elastic backscatter signal, two rotational Raman signals with different temperature dependence, and the vibrational Raman signal of water vapor. The main measurement variable of the UHOH RRL is temperature. For the HOPE campaign, the lidar receiver was optimized for high and low background levels, with a novel switch for the passband of the second rotational Raman channel. The instrument delivers atmospheric profiles of water vapor mixing ratio as well as particle backscatter coefficient and particle extinction coefficient as further products. As examples for the measurement performance, measurements of the temperature gradient and water vapor mixing ratio revealing the development of the atmospheric boundary layer within 25 h are presented. As expected from simulations, a reduction of the measurement uncertainty of 70% during nighttime was achieved with the new low-background setting. A two-mirror scanner allows for measurements in different directions. When pointing the scanner to low elevation, measurements close to the ground become possible which are otherwise impossible due to the non-total overlap of laser beam and receiving telescope field of view in the near range. An example of a low-level temperature measurement is presented which resolves the temperature gradient at the top of the stable nighttime boundary layer 100 m above the ground.

Gas transfer and water vapor condensation in cathode layers of air–hydrogen fuel cells

2016 ◽  
Vol 52 (4) ◽  
pp. 385-391
Author(s):  
V. M. Kozhevin ◽  
A. A. Tomasov ◽  
S. A. Gurevich ◽  
A. G. Zabrodskii
Keyword(s):  
Fuel Cells ◽  
Water Vapor ◽  
Vapor Condensation ◽  
Gas Transfer ◽  
Hydrogen Fuel Cells ◽  
Hydrogen Fuel ◽  
Water Vapor Condensation

scholarly journals Experimental Study of Condensation in a Thermoacoustic Cooler With Various 3D-Printed Regenerators Using Water Vapor as the Working Fluid

2019 ◽  
Vol 142 (5) ◽  
Author(s):  
Aibek Bekkulov ◽  
Andrew Luthen ◽  
Ben Xu
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Temperature Gradient ◽  
Sound Wave ◽  
Cooling Capacity ◽  
Working Fluid ◽  
Cooling Power ◽  
Parallel Plates ◽  
Humid Air ◽  
Condense Water

Abstract Thermoacoustics (TA) deals with the conversion of heat into sound and vice versa. The device that transfers energy from a low-temperature reservoir to a high-temperature one by utilizing acoustic work is called TA cooler (TAC). The main components of a typical TAC are a resonator, a porous regenerator (e.g., stack of parallel plates), and two heat exchangers. The thermoacoustic phenomenon takes place in the regenerator where a nonzero temperature gradient is imposed and interacts with the sound wave. The low temperature at the cold end of TAC can be used to condense water from the humid air and also reduce the moisture. In the current study, the sound wave with high intensity was produced to drive a TAC to produce cooling power at a cold temperature around 18 °C, using saturated water vapor as the working fluid. The drainage of condensate in the regenerator is the key to the system’s performance. This work is dedicated to investigate the effect from temperature gradient created in TAC on the condensation enhancement, by adopting three different designs of regenerators. A 3D printer was used to design and fabricate different structures of regenerator, and then, the systematic cooling capacity was tested and compared with different regenerators. This work can be extended to evaluate how the TA effect can be affected by the condensation if humid air is directly used as the working fluid. The potential application of this investigation can be an autonomous TAC system for water harvesting in arid areas.

scholarly journals Wavy temperature and density distributions formed in snow

1998 ◽  
Vol 26 ◽  
pp. 73-76 ◽  
Author(s):  
Sergey A. Sokratov ◽  
Norikazu Maeno
Keyword(s):  
Water Vapor ◽  
Temperature Gradient ◽  
Diffusion Coefficients ◽  
Snow Density ◽  
Steady Temperature ◽  
Vapor Diffusion ◽  
Density Distributions ◽  
Evaporation And Condensation ◽  
Wide Range ◽  
Measured Water

Precise measurements of temperature and density distributions in snow under an applied temperature gradient showed that alternation of evaporation and condensation zones is formed and causes the wavy patterns in quasi-steady temperature and density distributions. In samples with a snow density of 200–500 kg2m−3the wavelength was 3–7 cm and the amplitude was roughly 2°C. The present result gives a clue to explaining the wide range of previously measured water-vapor diffusion coefficients in snow.

scholarly journals Wavy temperature and density distributions formed in snow

1998 ◽  
Vol 26 ◽  
pp. 73-76
Author(s):  
Sergey A. Sokratov ◽  
Norikazu Maeno
Keyword(s):  
Water Vapor ◽  
Temperature Gradient ◽  
Diffusion Coefficients ◽  
Snow Density ◽  
Steady Temperature ◽  
Vapor Diffusion ◽  
Density Distributions ◽  
Evaporation And Condensation ◽  
Wide Range ◽  
Measured Water

Precise measurements of temperature and density distributions in snow under an applied temperature gradient showed that alternation of evaporation and condensation zones is formed and causes the wavy patterns in quasi-steady temperature and density distributions. In samples with a snow density of 200–500 kg2 m−3 the wavelength was 3–7 cm and the amplitude was roughly 2°C. The present result gives a clue to explaining the wide range of previously measured water-vapor diffusion coefficients in snow.

scholarly journals Vapor plumes in a tropical wet forest: spotting the invisible evaporation

2020 ◽  
Author(s):  
César Dionisio Jiménez-Rodríguez ◽  
Miriam Coenders-Gerrits ◽  
Bart Schilperoort ◽  
Adriana González-Angarita ◽  
Hubert Savenije
Keyword(s):  
Water Vapor ◽  
Temperature Gradient ◽  
Formation Process ◽  
Forest Canopy ◽  
Time Lapse ◽  
Minor Importance ◽  
Tropical Wet Forest ◽  
Air Convection ◽  
Rain Events ◽  
Lifting Condensation Level

Abstract. Forest evaporation exports a vast amount of water vapor from land ecosystems into the atmosphere. Meanwhile, evaporation during rain events is neglected or considered of minor importance in dense ecosystems. Air convection moves the water vapor upwards leading the formation of large invisible vapor plumes, while the identification of visible vapor plumes has not been studied yet. This work describes the formation process of vapor plumes in a tropical wet forest as evidence of evaporation processes happening during rain events. In the dry season of 2018 at La Selva Biological Station (LSBS) in Costa Rica it was possible to spot visible vapor plumes within the forest canopy. The combination of time-lapse videos at the canopy top with meteorological measurements along the canopy profile allowed to identify the conditions required for this process to happen. This phenomenon happened only during rain events, where evaporation measurements showed contributions of 1.8 mm d−1. Visible vapor plumes during day time occurred on the presence of precipitation (P), air convection identified by the temperature gradient (Δϴv / Δz) at 2 m height, and a lifting condensation level at 43 m height (Zlcl.43) smaller than 100 m.

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