Calibration of Raman Quantification Factors of Guest Molecules in Gas Hydrates and Their Application to Gas Exchange Processes Involving N2

2014 ◽  
Vol 60 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Junfeng Qin ◽  
Werner F. Kuhs
Keyword(s):  
Gas Exchange ◽  
Gas Hydrates ◽  
Guest Molecules ◽  
Exchange Processes

scholarly journals MATHEMATICAL MODELING OF THE THERMODYNAMIC PROCESS GAS-STEAM BUBBLES

2018 ◽  
Vol 1 (50) ◽  
pp. 220-226
Author(s):  
B. А. Kutnyi ◽  
А. М. Pavlenko
Keyword(s):  
Gas Hydrates ◽  
Solid Phase ◽  
Thermodynamic Process ◽  
Size Change ◽  
Process Gas ◽  
Exchange Processes ◽  
Pressure Steam ◽  
Liquid Heat ◽  
Velocity Pressure ◽  
Contact Liquid

A mathematical model that considers the inertial oscillations and thermodynamic components bubbles in liquid heat exchange processes, heat transfer on the boundary bubbles. Research of the dynamic characteristics of gas-steam bubbles in various size was conducted. After the calculations its temperature, velocity, pressure steam environment inside the bubble in time, graphs bubbles size change graphs were built . It is established that each bubble size has its oscillation frequency. Calculated speed phase transients and found that it is in its maximum during the bubble oscillation. For thermodynamic properties of the surface of contact liquid and gaseous phases defined amount of solid phase formed. The research results can be applied to optimize various of technological processes related to the boil, swelling materials, and the formation of gas hydrates in a fluid cavitation.

scholarly journals Surface gas-exchange processes of snow algae

2003 ◽  
Vol 100 (2) ◽  
pp. 562-566 ◽  
Author(s):  
W. E. Williams ◽  
H. L. Gorton ◽  
T. C. Vogelmann
Keyword(s):  
Gas Exchange ◽  
Snow Algae ◽  
Exchange Processes

Modeling the Gas Exchange Processes of a Modern Diesel Engine With an Integrated Physics-Based and Data-Driven Approach

2019 ◽  
Author(s):  
Jorge Pulpeiro Gonzalez ◽  
King Ankobea-Ansah ◽  
Elena Escuder Milian ◽  
Carrie M. Hall
Keyword(s):  
Diesel Engine ◽  
Gas Exchange ◽  
High Efficiency ◽  
Direct Injection ◽  
Data Driven ◽  
Model Framework ◽  
Variable Valve Actuation ◽  
Exchange Processes ◽  
Data Driven Approach ◽  
Using Data

Abstract The gas exchange processes of engines are becoming increasingly complex since modern engines leverage technologies including variable valve actuation, turbochargers, and exhaust gas recirculation. Control of these many devices and the underlying gas flows is essential for high efficiency engine concepts. If these processes are to be controlled and estimated using model-based techniques, accurate models are required. This work explores a model framework that leverages a data-driven model of the turbocharger along with submodels of the intercooler, intake and exhaust manifolds and engine processes to provide cylinder-specific predictions of the pressure and temperatures of the gases across the system. This model is developed and validated using data from a 2.0 liter VW turbocharged, direct-injection diesel engine and shown to provide accurate prediction of critical gas properties.

A New Single-Zone Multi-Stage Scavenging Model for Real-Time Emissions Control in Two-Stroke Engines

2019 ◽  
Author(s):  
Abdullah U. Bajwa ◽  
Mark Patterson ◽  
Taylor Linker ◽  
Timothy J. Jacobs
Keyword(s):  
Gas Exchange ◽  
Internal Combustion Engines ◽  
Engine Performance ◽  
Combustion Engines ◽  
Thermodynamic State ◽  
Multi Stage ◽  
Exchange Processes ◽  
Proposed Model ◽  
Perfect Mixing ◽  
And Control

Abstract Gas exchange processes in two-stroke internal combustion engines, i.e. scavenging, remove exhaust gases from the combustion chamber and prepare the fuel-oxidizer mixture that undergoes combustion. A non-negligible fraction of the mixture trapped in the cylinder at the conclusion of scavenging is composed of residual gases from the previous cycle. This can cause significant changes to the combustion characteristics of the mixture by changing its composition and temperature, i.e. its thermodynamic state. Thus, it is vital to have accurate knowledge of the thermodynamic state of the post-scavenging mixture to be able to reliably predict and control engine performance, efficiency and emissions. Several simple-scavenging models can be found in the literature that — based on a variety of idealized interaction modes between incoming and cylinder gases — calculate the state of the trapped mixture. In this study, boundary conditions extracted from a validated 1-D predictive model of a single-cylinder two-stroke engine are used to gauge the performance of four simple scavenging models. It is discovered that the assumption of thermal homogeneity of the incoming and exiting gases is a major source of inaccuracy. A new non-isothermal multi-stage single-zone scavenging model is thus, proposed to address some of the shortcomings of the four models. The proposed model assumes that gas-exchange in cross-scavenged two-stroke engines takes place in three stages; an isentropic blowdown stage, followed by perfect-displacement and perfect-mixing stages. Significant improvements in the trapped mixture state estimates were observed as a result.

scholarly journals Quantifying seasonal air-sea gas exchange processes using noble gas time-series: A design experiment

2006 ◽  
Vol 64 (2) ◽  
pp. 267-295 ◽  
Author(s):  
Rachel H. R. Stanley ◽  
William J. Jenkins ◽  
Scott C. Doney
Keyword(s):  
Time Series ◽  
Gas Exchange ◽  
Noble Gas ◽  
Design Experiment ◽  
Exchange Processes

Introducing new half-integer quadrupolar nuclei for solid state NMR of inclusion compounds

2015 ◽  
Vol 93 (9) ◽  
pp. 1014-1024
Author(s):  
Igor L. Moudrakovski ◽  
Christopher I. Ratcliffe ◽  
John A. Ripmeester
Keyword(s):  
Solid State ◽  
Gas Hydrates ◽  
Inclusion Compounds ◽  
Chemical Shift Anisotropy ◽  
Natural Abundance ◽  
Quadrupolar Nuclei ◽  
Guest Molecules ◽  
Quadrupolar Coupling ◽  
Nmr Techniques ◽  
The Impact

Broad developments in experimental NMR techniques have opened new and exciting opportunities for application of solid state nuclear magnetic resonance (SS NMR) in studies of gas hydrates and inclusion compounds in general. Perhaps the most important advance of the last 10 years was the extension into very high magnetic fields beyond 20 T. This progress is especially significant in studies concerned with low-γ, low natural abundance, and quadrupolar nuclei. This work reports our recent exploration of clathrate hydrates and other inclusion compounds (β-quinol, tert-Bu-Calix[4], and dodecasil-3C) with SS NMR of nuclei that were not so long ago completely out of reach for NMR, namely 131Xe, 83Kr, and 33S. Although 129Xe is a widely used NMR probe, applications of the low-γ isotope 131Xe were very scarce. Being a quadrupolar spin 3/2 nucleus, 131Xe provides an additional probe for sampling the electric field gradients in inclusion compounds. Another nucleus that has been seriously under-explored is 83Kr, with its very low γ being the main obstacle, and along with quadrupolar coupling we report the first detection of the chemical shift anisotropy in krypton. The relative values of the Sternheimer antishielding factors for 131Xe and 83Kr, obtained by comparison of the spectra of the two in identical cage environments, are also discussed. Though 33S NMR of solids is notoriously difficult due to its low γ, low natural abundance, and relatively large quadrupolar moment, working at the field of 21.1 T it was possible to acquire, in a reasonable time, natural abundance 33S SS NMR spectra of various H2S and SO2 gas hydrates and inclusion compounds. In most cases the spectra are dominated by the quadrupolar interactions, providing information on the symmetry of the cages encapsulating the guest molecules, and also show the effects of very rapid reorientation of the encaged H2S and SO2. The impact of the introduction of new NMR nuclei on hydrate research is discussed.

Spatial distribution and co-occurrence of surface-atmosphere energy and gas exchange processes over the code grid site

1995 ◽  
Vol 29 (21) ◽  
pp. 3169-3180 ◽  
Author(s):  
Constance M. Mitic ◽  
Peter H. Schuepp ◽  
Raymond L. Desjardins ◽  
Ian J. Macpherson
Keyword(s):  
Spatial Distribution ◽  
Gas Exchange ◽  
Surface Atmosphere ◽  
Exchange Processes ◽  
Grid Site
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