Measurement of Latent Heat by the Gas-Current Method

1942 ◽  
Vol 9 (1) ◽  
pp. A21-A25
Author(s):  
J. A. Goff ◽  
J. B. Hunter
Keyword(s):  
Experimental Data ◽  
Water Vapor ◽  
Latent Heat ◽  
Thermodynamic Analysis ◽  
Current Method ◽  
Interaction Constant ◽  
University Of Pennsylvania ◽  
Scientific School ◽  
Vapor Mixtures ◽  
American Society

Abstract The gas-current method of measuring latent heat appears to possess important advantages over other calorimetric methods. Preliminary results have been derived from a co-operative investigation carried out by the American Society of Heating and Ventilating Engineers and the Towne Scientific School, University of Pennsylvania, in which sufficiently reliable values of the interaction constant for air-and-water-vapor mixtures have been determined to permit an adequate thermodynamic analysis of the gas-current method. The present paper is devoted to the development of this analysis and its application to the reduction of certain experimental data recently obtained by one of the authors. The apparatus and method of conducting the experiments are also described.

The Thermodynamics of Air-Water Vapor Mixtures

2000 ◽  
Author(s):  
George A. Adebiyi
Keyword(s):  
Water Vapor ◽  
Thermodynamic Analysis ◽  
Ambient Air ◽  
Moist Air ◽  
Humidity Ratio ◽  
Atmospheric Air ◽  
Analysis And Evaluation ◽  
Vapor Mixtures ◽  
Reference Environment ◽  
Traditional Approaches

Abstract Traditional approaches to the thermodynamic analysis of processes involving air-water vapor mixtures are often limited to a psychrometric analysis and a first-law analysis. The substances involved are moist air (a mixture of dry air and moisture), and water (either as vapor, or as a liquid). A complete thermodynamic analysis must, however, include a second-law analysis. This article presents a complete outline for the thermodynamic analysis and evaluation of processes involving air-water vapor mixtures. With regards to exergy analysis, in particular, it is noted that the published and widely accepted equation for the exergy of moist air is indeterminate when the humidity ratio of the ambient air is zero. This raises questions about the appropriate reference environment for water or water vapor when the atmospheric air does not contain moisture. The alternative of an expanded reference environment, which includes a large pool of water co-existing with ambient air is proposed in this article. The resulting equations for the exergy of moist air are determinate regardless of the humidity ratio of the atmospheric air in the reference environment.

Studies of a Mixed Adsorption Layer of Butan-1-ol and o-Toluidine on Mercury Electrode

2002 ◽  
Vol 67 (11) ◽  
pp. 1579-1588 ◽  
Author(s):  
Dorota Sieńko ◽  
Dorota Gugała ◽  
Jolanta Nieszporek ◽  
Joanna Jankowska ◽  
Jadwiga Saba
Keyword(s):  
Thermodynamic Analysis ◽  
Adsorption Layer ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Interaction Constant ◽  
Repulsive Interaction ◽  
Surface Excess ◽  
Adsorption Parameters ◽  
Frumkin Isotherm ◽  
Adsorption Layers

The results of thermodynamic analysis of o-toluidine adsorption on a mercury electrode in the presence of various butan-1-ol amounts complete our previous studies on properties of mixed adsorption layers of toluidine isomers-butan-1-ol. The values of the relative surface excess Γ'°T obtained for o-toluidine show that adsorption of this compound decreases with increasing of butan-1-ol concentration. Analysis of adsorption parameters derived from the Frumkin isotherm indicates that in the presence of 0.33 M BuOH in 1 M NaClO4 with adjusted pH 3 as supporting electrolyte, ∆G0 values for o-toluidine are the highest and, at the same time, the strongest repulsive interaction occurs. In the presence of 0.11 M butan-1-ol, smaller values of ∆G0 for o-toluidine correspond to weaker repulsive interaction. Therefore the change of the Γ'°T value for o-toluidine as a function of butan-1-ol concentration is the result of mutual changes of ∆G0 and interaction constant A between adsorbate molecules.

scholarly journals Thermodynamic analysis of synthesis of cyclopentanol from cyclopentene and comparison with experimental data

2015 ◽  
Vol 5 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Benzhen Yao ◽  
Zhiqing Wang ◽  
Tiancun Xiao ◽  
Fahai Cao ◽  
Peter P. Edwards ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Analysis ◽  
Comparison With Experimental Data

Fully Plastic Failure Stresses and Allowable Crack Sizes for Circumferentially Surface Cracked Pipes Subjected to Tensile Loading

2021 ◽  
Author(s):  
Kunio Hasegawa ◽  
David Dvorak ◽  
Vratislav Mares ◽  
Bohumir Strnadel ◽  
Yinsheng Li
Keyword(s):  
Experimental Data ◽  
Bending Moment ◽  
Limit Load ◽  
Tensile Loading ◽  
Crack Size ◽  
Plastic Failure ◽  
Circumferential Crack ◽  
Asme Code ◽  
American Society ◽  
Better Than

Abstract Fully plastic failure stresses for circumferentially surface cracked pipes subjected to tensile loading can be estimated by means of limit load criteria based on the net-section stress approach. Limit load criteria of the first type (labelled LLC-1) were derived from the balance of uniaxial forces. Limit load criteria of the second type are given in Section XI of the ASME (American Society of Mechanical Engineering) Code, and were derived from the balance of bending moment and axial force. These are labelled LLC-2. Fully plastic failure stresses estimated by using LLC-1 and LLC-2 were compared. The stresses estimated by LLC-1 are always larger than those estimated by LLC-2. From the literature survey of experimental data, failure stresses obtained by both types of LLC were compared with the experimental data. It can be stated that failure stresses calculated by LLC-1 are better than those calculated by LLC-2 for shallow cracks. On the contrary, for deep cracks, LLC-2 predictions of failure stresses are fairly close to the experimental data. Furthermore, allowable circumferential crack sizes obtained by LLC-1 were compared with the sizes given in Section XI of the ASME Code. The allowable crack sizes obtained by LLC-1 are larger than those obtained by LLC-2. It can be stated that the allowable crack size for tensile stress depends on the condition of constraint of the pipe, and the allowable cracks given in Section XI of the ASME Code are conservative.

Scanning 10-W Water Vapor DIAL for the Investigation of Atmospheric Turbulence and Land-Atmosphere Feedback

2021 ◽  
Author(s):  
Andreas Behrendt ◽  
Florian Spaeth ◽  
Volker Wulfmeyer
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Latent Heat ◽  
Atmospheric Turbulence ◽  
Latent Heat Flux ◽  
Climate Models ◽  
Weather Forecast ◽  
Surface Characteristics ◽  
Scanning System ◽  
Forecast Models

<p>We will present recent measurements made with the water vapor differential absorption lidar (DIAL) of University of Hohenheim (UHOH). This scanning system has been developed in recent years for the investigation of atmospheric turbulence and land-atmosphere feedback processes.</p><p>The lidar is housed in a mobile trailer and participated in recent years in a number of national and international field campaigns. We will present examples of vertical pointing and scanning measurements, especially close to the canopy. The water vapor gradients in the surface layer are related to the latent heat flux. Thus, with such low-elevation scans, the latent heat flux distribution over different surface characteristics can be monitored, which is important to verify and improve both numerical weather forecast models and climate models.</p><p>The transmitter of the UHOH DIAL consists of a diode-pumped Nd:YAG laser which pumps a Ti:sapphire laser. The output power of this laser is up to 10 W. Two injection seeders are used to switch pulse-to-pulse between the online and offline signals. These signals are then either directly sent into the atmosphere or coupled into a fiber and guided to a transmitting telescope which is attached to the scanner unit. The receiving telescope has a primary mirror with a dimeter of 80 cm. The backscatter signals are recorded shot to shot and are typically averaged over 0.1 to 1 s.</p>

Water vapor sorption on Marcellus shale: measurement, modeling and thermodynamic analysis

Fuel ◽  
2017 ◽  
Vol 209 ◽  
pp. 606-614 ◽  
Author(s):  
Xu Tang ◽  
Nino Ripepi ◽  
Katherine A. Valentine ◽  
Cigdem Keles ◽  
Timothy Long ◽  
...  
Keyword(s):  
Water Vapor ◽  
Thermodynamic Analysis ◽  
Marcellus Shale ◽  
Water Vapor Sorption ◽  
Vapor Sorption

Subcloud and Cloud-Base Latent Heat Fluxes during Shallow Cumulus Convection

2019 ◽  
Vol 77 (3) ◽  
pp. 1081-1100 ◽  
Author(s):  
Neil P. Lareau
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Latent Heat ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Cloud Base ◽  
Cumulus Convection ◽  
Mixing Ratio ◽  
Convective Boundary ◽  
Water Vapor Mixing Ratio

Abstract Doppler and Raman lidar observations of vertical velocity and water vapor mixing ratio are used to probe the physics and statistics of subcloud and cloud-base latent heat fluxes during cumulus convection at the ARM Southern Great Plains (SGP) site in Oklahoma, United States. The statistical results show that latent heat fluxes increase with height from the surface up to ~0.8Zi (where Zi is the convective boundary layer depth) and then decrease to ~0 at Zi. Peak fluxes aloft exceeding 500 W m−2 are associated with periods of increased cumulus cloud cover and stronger jumps in the mean humidity profile. These entrainment fluxes are much larger than the surface fluxes, indicating substantial drying over the 0–0.8Zi layer accompanied by moistening aloft as the CBL deepens over the diurnal cycle. We also show that the boundary layer humidity budget is approximately closed by computing the flux divergence across the 0–0.8Zi layer. Composite subcloud velocity and water vapor anomalies show that clouds are linked to coherent updraft and moisture plumes. The moisture anomaly is Gaussian, most pronounced above 0.8Zi and systematically wider than the velocity anomaly, which has a narrow central updraft flanked by downdrafts. This size and shape disparity results in downdrafts characterized by a high water vapor mixing ratio and thus a broad joint probability density function (JPDF) of velocity and mixing ratio in the upper CBL. We also show that cloud-base latent heat fluxes can be both positive and negative and that the instantaneous positive fluxes can be very large (~10 000 W m−2). However, since cloud fraction tends to be small, the net impact of these fluxes remains modest.

Solubility of celecoxib in 1-propanol + water mixtures at T= (293.2–313.2) K: experimental data and thermodynamic analysis

2018 ◽  
Vol 58 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Esmail Mohammadian ◽  
Elaheh Rahimpour ◽  
Mohammad Barzegar-Jalali ◽  
Sina Dadmand ◽  
Fleming Martinez ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Analysis

Thermodynamic analysis of a packed bed latent heat thermal storage system simulated by an effective packed bed model

Energy ◽  
2017 ◽  
Vol 140 ◽  
pp. 861-878 ◽  
Author(s):  
R. Pakrouh ◽  
M.J. Hosseini ◽  
A.A. Ranjbar ◽  
R. Bahrampoury
Keyword(s):  
Latent Heat ◽  
Thermodynamic Analysis ◽  
Storage System ◽  
Thermal Storage ◽  
Packed Bed
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