Determination of synthetic hydrate content in sand specimens using dielectrics

2006 ◽  
Vol 43 (6) ◽  
pp. 551-562 ◽  
Author(s):  
J R Kliner ◽  
J LH Grozic
Keyword(s):  
Dielectric Constant ◽  
Gas Hydrates ◽  
Hydrate Formation ◽  
Time Domain Reflectometry ◽  
Energy Yield ◽  
Ottawa Sand ◽  
Volumetric Expansion ◽  
Specific Temperature ◽  
Pressure Stability

Gas hydrates are solid crystalline compounds (clathrates) that encage gas molecules inside the lattices of hydrogen bonded water molecules within a specific temperature–pressure stability zone. It is imperative that reliable detection and quantification modi operandi are developed, as proposed in this research, to identify hydrate-laden strata and determine economic viability of this potential energy yield. This paper presents the experimental analysis of synthetic refrigerant (R-11) hydrates in 20/30 Ottawa sand using dielectric principles to determine specific hydrate content. Hydrate specimens were constructed via moist tamped Ottawa sand, purged with carbon dioxide (CO2), saturated with de-aired water, and mixed with a known amount of R-11 to produce precise hydrate contents. The specimen's bulk dielectric constant was measured using a ThetaProbe by applying the principles of time domain reflectometry (TDR). A distinct relationship between hydrate content and the bulk dielectric constant of sand specimens is determined, as well; volumetric expansion associated with hydrate formation is also portrayed.Key words: gas hydrates, synthetic hydrates, dielectrics, Ottawa sand, laboratory testing.

scholarly journals Time domain reflectrometry measurements using a movable obstacle for the determination of dielectric profiles

2008 ◽  
Vol 6 ◽  
pp. 1-4
Author(s):  
B. Will ◽  
M. Gerding ◽  
S. Schultz ◽  
B. Schiek
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Time Domain ◽  
Measurement Techniques ◽  
Measurement Data ◽  
Time Domain Reflectometry ◽  
Dielectric Measurement ◽  
Effective Dielectric Constant ◽  
Pulse Delay

Abstract. Microwave techniques for the measurement of the permittivity of soils including the water content of soils and other materials, especially TDR (time domain reflectometry), have become accepted as routine measurement techniques. This summary deals with an advanced use of the TDR principle for the determination of the water content of soil along a probe. The basis of the advanced TDR technique is a waveguide, which is inserted into the soil for obtaining measurements of the effective soil permittivity, from which the water content is estimated, and an obstacle, which can mechanically be moved along the probe and which acts as a reference reflection for the TDR system with an exactly known position. Based on the known mechanical position of the reference reflection, the measured electrical position can be used as a measure for the effective dielectric constant of the environment. Thus, it is possible to determine the effective dielectric constant with a spatial resolution given by the step size of the obstacle displacement. A conventional industrial TDR-system, operating in the baseband, is used for the signal generation and for the evaluation of the pulse delay time of the obstacle reflection. Thus, a cost effective method for the acquisition of the dielectric measurement data is available.

scholarly journals Experimental Determination of TDR Calibration Relationship for Pyroclastic Ashes of Campania (Italy)

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3727 ◽  
Author(s):  
Giovanna Capparelli ◽  
Gennaro Spolverino ◽  
Roberto Greco
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Organic Matter Content ◽  
Free Water ◽  
Time Domain Reflectometry ◽  
Dielectric Constants ◽  
Phase System ◽  
Three Phase ◽  
The Relationship

Time domain reflectometry (TDR) is one of the most widely used techniques for indirect determination of soil volumetric water content (θ). TDR measures the relative dielectric constant (εr) which, in a three-phase system like the soil, depends on water, air, and solid matrix dielectric constants. Since dielectric constant of water is much larger than the other two, εr of bulk soil mainly depends on water content. In many cases, the application of TDR requires a specific calibration of the relationship θ(εr) to get quantitatively accurate estimates of soil water content. In fact, the relationship θ(εr) is influenced by various soil properties, such as clay content, organic matter content, bulk density, and aggregation. Numerous studies have shown that pyroclastic soils often exhibit a peculiar dielectric behavior. In Campania (Southern Italy) wide mountainous areas are covered by layered pyroclastic deposits of ashes (loamy sands) and pumices (sandy gravels), often involved in the triggering of landslides induced by rainwater infiltration. Reliable field measurements of water content of such soils are therefore important for the assessment of landslide risk. Hence, in this paper, the θ(εr) relationship has been experimentally determined on samples of typical pyroclastic soil of Campania, collected around Sarno, reconstituted with different porosities. The aim of the study is to identify specific calibration relationships for such soils based not only on empirical approaches. In this respect, a three-phase dielectric mixing model with a variable exponent is introduced, and the variable value of the exponent is related to the different dielectric properties of bond and free water within the soil pores.

scholarly journals Models for moisture estimation in different horizons of yellow argisol using TDR

2017 ◽  
Vol 38 (4) ◽  
pp. 1727
Author(s):  
Karla Silva Santos Alvares de Almeida ◽  
Luciano Da Silva Souza ◽  
Vital Pedro Da Silva Paz ◽  
Maurício Antônio Coelho Filho ◽  
Eduardo Holzapfel Hoces
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Time Domain Reflectometry ◽  
Volumetric Water Content ◽  
Advantages And Disadvantages ◽  
Disturbed Soil ◽  
Cubic Polynomial ◽  
Indirect Technique ◽  
Moisture Estimation

The determination of soil moisture is very important because it is the property with the most influence on the dielectric constant of the medium. Time-domain reflectometry (TDR) is an indirect technique used to estimate the water content of the soil (?) based on its dielectric constant (Ka). Like any other technique, it has advantages and disadvantages. Among the major disadvantages is the need for calibration, which requires consideration of the soil characteristics. This study aimed to perform the calibration of a TDR100 device to estimate the volumetric water content of four horizons of a Yellow Argisol. Calibration was performed under laboratory conditions using disturbed soil samples contained in PVC columns. The three rods of the handcrafted probes were vertically installed in the soil columns. Weight measurements with digital scales and daily readings of the dielectric constant with the TDR device were taken. For all soil horizons evaluated, the best fits between the dielectric constant and the volumetric water content were related to the cubic polynomial model. The Ledieu model overestimated by approximately 68 % the volumetric water content in the A and AB horizons, and underestimating by 69 % in Bt2, in relation to volumetric water content obtained by gravimetry. The underestimation by linear, Topp, Roth, and Malicki models ranged from 50 % to 85 % for all horizons.

scholarly journals Determination of the permittivity of soils by use of double transmission measurements

2009 ◽  
Vol 7 ◽  
pp. 1-4 ◽  
Author(s):  
B. Will ◽  
M. Gerding
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Delay Time ◽  
Effective Permittivity ◽  
Time Domain Reflectometry ◽  
Effective Dielectric Constant ◽  
Step Size ◽  
Transmission Method ◽  
Average Value

Abstract. Delay time measurements, e.g. time domain reflectometry (TDR), are a well-established method for the measurement of permittivity of various materials, especially soils. However, common measurement systems only provide one average value of the dielectric constant along the length of the TDR probe. This contribution deals with an advanced application of the TDR principle, the so-called double transmission method, for the determination of the water content of soil along a probe. To apply the advanced TDR technique, a probe, realized by a combination of a transmission line and a dielectric obstacle, which can mechanically be moved along the probe, is used. The probe is inserted into the soil to measure the effective soil permittivity. Thus, the water content along the probe can be estimated by means of the effective permittivity. Based on the known mechanical position of the reflection at the end of the probe and the position of the obstacle, the measured delay time can be used as a measure for the effective dielectric constant of the environment surrounding the obstacle. Thus, it is possible to determine the effective dielectric constant with a spatial resolution given by the step size of the obstacle displacement.

scholarly journals DETERMINATION OF DISSOCIATION STAGE OF GAS HYDRATES BASED ON THE ANALYSIS OF NMR RELAXOMETRY METHOD DATA

2020 ◽  
pp. 4-12
Author(s):  
M. Y. Shumskayte ◽  
A. Yu. Manakov ◽  
V. N. Glinskikh ◽  
A. D. Duchkov
Keyword(s):  
Gas Hydrates ◽  
Hydrate Formation ◽  
Clay Content ◽  
Distilled Water ◽  
Hydrate Dissociation ◽  
Reservoir Rocks ◽  
Nmr Relaxometry ◽  
Synthetic Gas ◽  
Tetrahydrofuran Solution

A model of synthetic gas hydrates in a mixture of quartz pellets is considered using by tetrahydrofuran solution based on distilled water. The analysis of the NMR-characteristics of tetrahydrofuran hydrate in clayed sand is performed. The stages of hydrate dissociation excluding water contribution are established and it is shown that the NMR-relaxometry method is sensitive to the clay content. The obtained results allow us to more detailed study the processes of hydrate formation in real reservoir rocks and their physical characteristics.

The formation of gas hydrates under shock wave impact on the bubble media (two-dimensional case)

2010 ◽  
Vol 7 ◽  
pp. 90-97
Author(s):  
M.N. Galimzianov ◽  
I.A. Chiglintsev ◽  
U.O. Agisheva ◽  
V.A. Buzina
Keyword(s):  
Shock Wave ◽  
Gas Hydrates ◽  
Hydrate Formation ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Wave Impact ◽  
Bubble Liquid ◽  
One Dimensional ◽  
Bubble Media ◽  
Main Factors

Formation of gas hydrates under shock wave impact on bubble media (two-dimensional case) The dynamics of plane one-dimensional shock waves applied to the available experimental data for the water–freon media is studied on the base of the theoretical model of the bubble liquid improved with taking into account possible hydrate formation. The scheme of accounting of the bubble crushing in a shock wave that is one of the main factors in the hydrate formation intensification with increasing shock wave amplitude is proposed.

Thermodynamic Modelling of Gas Hydrate Formation in the Presence of Inhibitors and the Consideration of their Effect

2014 ◽  
Vol 14 (1) ◽  
pp. 45
Author(s):  
Peyman Sabzi ◽  
Saheb Noroozi
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Low Temperatures ◽  
Hydrate Formation ◽  
Transportation Systems ◽  
Flow Lines ◽  
Main Approach ◽  
Efficient Inhibitor ◽  
System A ◽  
Gas Hydrate Formation

Gas hydrates formation is considered as one the greatest obstacles in gas transportation systems. Problems related to gas hydrate formation is more severe when dealing with transportation at low temperatures of deep water. In order to avoid formation of Gas hydrates, different inhibitors are used. Methanol is one of the most common and economically efficient inhibitor. Adding methanol to the flow lines, changes the thermodynamic equilibrium situation of the system. In order to predict these changes in thermodynamic behavior of the system, a series of modelings are performed using Matlab software in this paper. The main approach in this modeling is on the basis of Van der Waals and Plateau's thermodynamic approach. The obtained results of a system containing water, Methane and Methanol showed that hydrate formation pressure increases due to the increase of inhibitor amount in constant temperature and this increase is more in higher temperatures. Furthermore, these results were in harmony with the available empirical data.Keywords: Gas hydrates, thermodynamic inhibitor, modelling, pipeline blockage

scholarly journals A design concept of active cooling for tailored forming workpieces during induction heating

2021 ◽  
Vol 15 (2) ◽  
pp. 177-186
Author(s):  
Caner-Veli Ince ◽  
Anna Chugreeva ◽  
Christoph Böhm ◽  
Fadi Aldakheel ◽  
Johanna Uhe ◽  
...  
Keyword(s):  
Dissimilar Materials ◽  
Heating Process ◽  
Algorithmic Approach ◽  
Cooling Strategy ◽  
Heating And Cooling ◽  
Temperature Constraint ◽  
Inhomogeneous Temperature ◽  
Specific Temperature ◽  
Tailored Forming

AbstractThe demand for lightweight construction is constantly increasing. One approach to meet this challenge is the development of hybrid components made of dissimilar materials. The use of the hybrid construction method for bulk components has a high potential for weight reduction and increased functionality. However, forming workpieces consisting of dissimilar materials requires specific temperature profiles for achieving sufficient formability. This paper deals with the development of a specific heating and cooling strategy to generate an inhomogeneous temperature distribution in hybrid workpieces. Firstly, the heating process boundaries with regard to temperature parameters required for a successful forming are experimentally defined. Secondly, a design based on the obtained cooling strategy is developed. Next a modelling embedded within an electro-thermal framework provides the basis for a numerical determination of admissible cooling rates to fulfil the temperature constraint. Here, the authors illustrate an algorithmic approach for the optimisation of cooling parameters towards an effective minimum, required for applicable forming processes of tailored forming.

scholarly journals Rapid Gas Hydrate Formation—Evaluation of Three Reactor Concepts and Feasibility Study

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3615
Author(s):  
Florian Filarsky ◽  
Julian Wieser ◽  
Heyko Juergen Schultz
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Synthetic Natural Gas ◽  
Operation Conditions ◽  
Gas Hydrate Formation ◽  
Gas Conditioning ◽  
And Storage ◽  
Economic Considerations ◽  
High Storage

Gas hydrates show great potential with regard to various technical applications, such as gas conditioning, separation and storage. Hence, there has been an increased interest in applied gas hydrate research worldwide in recent years. This paper describes the development of an energetically promising, highly attractive rapid gas hydrate production process that enables the instantaneous conditioning and storage of gases in the form of solid hydrates, as an alternative to costly established processes, such as, for example, cryogenic demethanization. In the first step of the investigations, three different reactor concepts for rapid hydrate formation were evaluated. It could be shown that coupled spraying with stirring provided the fastest hydrate formation and highest gas uptakes in the hydrate phase. In the second step, extensive experimental series were executed, using various different gas compositions on the example of synthetic natural gas mixtures containing methane, ethane and propane. Methane is eliminated from the gas phase and stored in gas hydrates. The experiments were conducted under moderate conditions (8 bar(g), 9–14 °C), using tetrahydrofuran as a thermodynamic promoter in a stoichiometric concentration of 5.56 mole%. High storage capacities, formation rates and separation efficiencies were achieved at moderate operation conditions supported by rough economic considerations, successfully showing the feasibility of this innovative concept. An adapted McCabe-Thiele diagram was created to approximately determine the necessary theoretical separation stage numbers for high purity gas separation requirements.

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