Supercritical Methane Research Articles

A New Method to Calculate the Absolute Amount of High-Pressure Adsorption of Supercritical Fluid

In the paper we developed a new method to determine the absolute amount of adsorption. This method relies on the excess adsorption isotherm and the density profile in the pore of one material. To compute the density profile and decrease complex calculation of obtaining the absolute amount of adsorption we introduced Simplified Local-Density (SLD) model. A few of appropriate parameters were acquired to calculate the density profile through SLD models the adsorption isotherm of methane on AX-21 activated carbon. In these parameters specific surface area and slit width is close to the true value of the AX-21 activated carbon. And we found SLD can accurately simulate the adsorption of supercritical methane on activated carbon and the precision rises up as temperature raises. The corresponding application of our method on adsorption of methane on AX-21 activated carbon was introduced at different temperature from 233 to 333K. The absolute isotherms of adsorption calculated by our method are reasonable when compared to other results.

Evaluation of gas sorption-induced internal swelling in coal

Gas sorption plays an important role in permeability evolution and gas flow in coal. Many efforts have been made to evaluate the effect of gas sorption on permeability. For example, the total gas sorption matrix swelling is divided in to two pars, one acts on cleat (internal swelling) and the other contributes to coal block deformation. Nevertheless, this effect has not been fully identified yet. This paper proposed a method that regressed the internal swelling by using a proposed permeability model. The internal swelling values under different boundary conditions were calculated by using the well-measured permeability from two published papers. The results indicated that the internal swelling was positively proportional to pore pressure and negatively proportional to confining stress for gaseous and supercritical methane and gaseous carbon dioxide. For supercritical carbon dioxide, the internal swelling increased with increasing pore pressure but was almost independent of confining stress. The internal swelling may be affected by sorbate type, coal structure and coal lithotypes in addition to pore pressure and confining stress. The internal swelling ratio that is defined as the ratio of the internal swelling to the gas sorption-induced swelling of coal matrix or coal block was also calculated. The internal swelling ratio may roughly keep constant during coalbed methane recovery when the in situ stress was greater than 5MPa. This assumption was practically useful for engineering application as it linked the effect of gas sorption on in situ permeability to the easy-measured sorption strain. Although the constant value cannot capture the full nature of the in situ internal swelling ratio, it was still capable of improving the accuracy of permeability prediction to some extent.

Heat transfer modeling for supercritical methane flowing in rocket engine cooling channels

To investigate the methane behavior inside rocket engine cooling channels, a test article has been specifically designed by the Italian Aerospace Research Center. In this study, the expected wall and coolant behavior of this test article is analyzed by a three-dimensional conjugate heat transfer model. Different coolant pressure and surface roughness levels are considered in order to understand their influence on the heat transfer capability of the cooling system. Results show that heat transfer deterioration may occur in principle when methane is operated in near-critical condition. However, the resultant wall temperature peak reduces for increasing coolant pressure and for increasing surface roughness.

Fiber refractometer to detect and distinguish carbon dioxide and methane leakage in the deep ocean

Deep ocean injection of carbon dioxide into subsea geologic formations carries a risk of carbon dioxide leakage as well as leakage of methane from petroleum bearing formations that injection wells may penetrate. Therefore, leakage monitoring technology for this application must detect carbon dioxide and distinguish it from methane. Here we demonstrate an all-optical approach to detect and differentiate between liquid carbon dioxide and supercritical methane bubbles in synthetic seawater at 9.65MPa. This method employs fiber tip refractometry, a fiber optic measurement technique that is sensitive to the refractive index of the surrounding medium. Carbon dioxide and methane bubbles are clearly detected as they pass the sensor tip and these species are clearly distinguished from each other. Interferometric signals are also observed in association with the transition of bubbles onto and off of the sensor tip.

Experimental investigation of supercritical methane injection in oil fields on salt deposit formation by gas anti-solvent process

Salt precipitation and salt block formation are the common problems in the gas injection wells. The salt precipitation may produce a severe loss of well injection which leads to a complete blockage of injection. The wells which located at south oil field of Iran are faced with such problems. The analysis of produced sediments shows that more than 93% of those compounds are sodium chloride (NaCl). Different mechanisms can affect the formation of deposit. By injecting supercritical methane into oil fields, it was proved that one of the most probable mechanisms in such condition is gas anti-solvent. In this work, two formation waters at different temperature and pressure conditions were evaluated. The results showed that significant amount of precipitation was observed in one of those water formations while in the other one no precipitation was detected. Furthermore, the effect of operating variables including temperature and pressure on the quantity of formed deposit has been investigated. Moreover, the obtained experimental results were simulated using the PHREEQC software.

Molecular Simulations of Supercritical Fluid Permeation through Disordered Microporous Carbons

Fluid transport through microporous carbon-based materials is inherent in numerous applications, ranging from gas separation by carbon molecular sieves to natural gas production from coal seams and gas shales. The present study investigates the steady-state permeation of supercritical methane in response to a constant cross-membrane pressure drop. We performed dual control volume grand canonical molecular dynamics (DCV-GCMD) simulations to mimic the conditions of actual permeation experiments. To overcome arbitrary assumptions regarding the investigated porous structures, the membranes were modeled after the CS1000a and CS1000 molecular models, which are representative of real microporous carbon materials. When adsorption-induced molecular trapping (AIMT) mechanisms are negligible, we show that the permeability of the microporous material, although not significantly sensitive to the pressure gradient, monotonically decreases with temperature and reservoir pressures, consistent with diffusion theory. However, when AIMT occurs, the permeability increases with temperature in agreement with experimental data found in the literature.

Experimental investigation on convective heat transfer from a horizontal miniature tube to methane at supercritical pressures

Heat transfer of supercritical cryogenic methane in miniature tube has been experimentally investigated. Experimental conditions included pressures of 5–15 MPa, mass velocities of 6000–150,000 kg m−2 s−1 and heat fluxes of 1–16 MW m−2. The mass flux, heat flux and pressure effect were analyzed. A physically reasonable property averaging technique, Probability Density Function (PDF)-based time-averaged properties, were proposed for accounting for the effect of highly nonlinear dependency of properties on instantaneous turbulent temperature. A semi-empirical new correlation evaluated by PDF-based time-averaged properties for convection heat transfer of supercritical cryogenic methane was developed. The experimental Nusselt numbers were compared with those calculated with empirical correlations. The Dittus–Boelter and Gnielinski correlations overestimate the measurements in the pseudo-critical region since they could not accurately reflect the properties variations.The newly developed PDF correlation works so well that more than 85% experimental data are captured within an accuracy of 25%. Jackson acceleration criterion is found valid in evaluating the acceleration effect and works well in predicting heat transfer deterioration occurring in present experiments.

Onset of Heat Transfer Deterioration in Supercritical Methane Flow Channels

The deterioration of forced convection heat transfer can affect channel flows of supercritical fluids and therefore has to be taken into consideration when dealing with regenerative cooling of liquid rocket engines. A threshold value of the ratio between the heat flux and the specific mass flow rate is identified as the main parameter controlling the heat transfer deterioration onset. The threshold parameter depends on the specific thermodynamic conditions of the coolant and in particular on its pressure level. In the present study, a parametric numerical analysis has been carried out on the flow of supercritical methane in heated channels, for an assigned inlet temperature level and varying the inlet pressure. A correlation for the threshold parameter as a function of pressure is then proposed on the basis of the obtained results.

Formation of Liquid Methane–Water Mixture during Combustion of a Laminar Methane Jet at Supercritical Pressures

During the study of soot formation in laminar jet flames of methane at elevated pressures in a high-pressure combustion chamber, we have observed an anomalous occurrence at the chamber pressures of 6 MPa and higher. At pressures between 6 and 9 MPa, after the laminar methane jet flame had been stabilized on a co-flow circular nozzle-type burner, one of the following occurrences was observed: (a) the jet flame is completely extinguished without any external interference, and immediately after, a liquid material started to flow out of the fuel nozzle, and (b) the jet flame started flickering or changing its shape, and at the same time, a liquid stream started trickling out of the nozzle. This outflowing liquid influenced the jet flame by widening the flame near its base and decreasing the visible flame height. In consideration of the temperatures and the pressures involved, the liquid is believed to be a mixture of methane and water formed by the water vapor in the combustion products of the flame mixing with supercritical methane inside the nozzle.

Mobility ratio, relative permeability and sweep efficiency of supercritical CO2 and methane injection to enhance natural gas and condensate recovery: Coreflooding experimentation

Enhanced natural gas and condensate recovery has more recently stimulated an immense popular interest in oil exploration and production. While numerous laboratory and computational studies of carbon dioxide (CO2) injection into conventional oil reservoirs have been reported in the open literature, scarce work is being disclosed on CO2 displacement characteristics with both natural gas and liquid condensate where the displacement mechanisms are well-known to be significantly different to those in conventional gas/oil systems.This paper quantitatively investigates the recovery efficiency, pattern behavior and relative permeability of: (1) condensate following supercritical carbon dioxide (SCCO2) injection, methane injection and the injection of their mixtures; and (2) natural gas of various compositions following pure SCCO2 injection. This investigation includes two sets of coreflooding experiments: the first is to observe the microscale displacement efficiency and stability of natural gas following pure SCCO2 injection while the second was conducted to study the percentage of condensate recovery following the injection of different SCCO2-methane concentrations. This work is part of an integrated enhanced natural gas and condensate recovery project conducted for a local reservoir in Western Australia. This data will help the operators develop operational and design strategies for their current and future EOR projects, as well as provide parameters for full-field simulation practices.

Modified potential theory for modeling supercritical gas adsorption

Theoretical modeling of adsorption plays a crucial role in providing better understanding of the adsorption phenomena, isotherms and isosteric heats. However, when modeling the adsorption of gas mixtures containing hydrogen, it is necessary to accommodate a wide temperature range because of hydrogen's low critical temperature. In this work, we extend the multicomponent potential theory of adsorption's (MPTA) capability of predicting adsorption isotherms to a wide temperature range by introducing a temperature dependent Dubinin potential parameter and use it to model adsorption isotherms of supercritical hydrogen, nitrogen and methane on various activated carbons. This extended MPTA can accurately predict the adsorption isotherms when used with NIST equation of state (EOS). The resulting isosteric heats of adsorption of hydrogen agree well with the experimental data for similar volume filling scenarios. Hydrogen's low temperature adsorbed-phase pressure inside the activated carbon's micropore volume reaches the melting pressure of solid hydrogen. This causes the transition of adsorbed hydrogen from supercritical gas to solid-like phase which is clearly observed in our model. Our study, thus, provides a better understanding of physisorption of hydrogen inside the micropores.

CFD analysis of transcritical methane in rocket engine cooling channels

The knowledge of the flow behavior inside cooling channels is of great importance to improve design and performance of regeneratively cooled rocket engines. The modeling of the coolant flow is a challenging task because of its particular features, such as the high wall temperature gradient, the high Reynolds number and the three-dimensional geometry of the passages. In case of methane as coolant, a further complication is the transcritical operating condition of the fluid. In this thermodynamic regime large changes of the fluid properties can greatly influence the coolant flow-field and the heat transfer. Numerical simulations of transcritical methane flow-field in asymmetrically heated rectangular channel with high aspect ratio and strong wall temperature differences are carried out by a suitable CFD solver. Results are discussed in detail and compared with supercritical methane flow-fields. Finally the aspect ratio effect on methane flow is analyzed by comparison of four different rectangular cooling channel geometries with fixed hydraulic diameter and coolant flows with the same mass flow-rate per unit area. Emphasis is given to the comparison of fluid cooling performance and pressure loss.

Glycol Loss in a Gaseous System: Thermodynamic Assessment Test of Experimental Solubility Data

Triethylene glycol (TEG) is generally used to adjust the water dew point in natural gas processes. Unfortunately, only very few sets of experimental data regarding solubilities of these humidity absorbents in supercritical natural gas components have been reported in the literature partly due to the difficulties in such very low concentration measurements. Therefore, a satisfactory accuracy of measurements is not obvious, and the reliability of the corresponding data must be checked prior to their application. In this study, we focus on presenting the results of a thermodynamic assessment test (consistency test) for experimental solubility data of triethylene glycol in supercritical methane and carbon dioxide. The Gibbs–Duhem equation in terms of pressure, fugacity coefficients, solubilities of triethylene glycol in gas phase, and compressibility factor of gas phase is applied for the consistency test. The Soave–Redlich–Kwong (SRK) equation of state (EoS) along with the van der Waals (vdW2) mixing rules i...

Experimental and Theoretical Studies of Supercritical Methane Adsorption in the MIL-53(Al) Metal Organic Framework

The adsorption equilibrium properties of supercritical methane in the large-pore (lp) structure of the MIL-53(Al) metal organic framework were studied experimentally by gravimetric adsorption and theoretically by grand canonical Monte Carlo (GCMC) simulation. The adsorption experiments span a broad range of pressures (0.01–7 MPa) and temperatures (303–353 K). In our molecular simulation work, MIL-53lp(Al) is assumed to have a perfect, rigid lattice, and both fluid–fluid and solid–fluid interactions are modeled using the TraPPE-UA force field. The adsorption isotherms and isosteric heats of adsorption predicted by GCMC simulation, without any reparametrization of the TraPPE-UA force field parameters, are in good agreement with the experimental measurements. Our molecular simulations predict that the amount of methane adsorbed in the porous framework of MIL-53lp(Al) at 298.15 K and 3.5 MPa is 5.79 mol/kg, yielding a methane storage capacity of 132.6 v/v (volumes of stored gas, measured at standard conditions, per storage volume) for a monolithic block and 107.2 v/v for the theoretical limit of a close-packing of uniform spherical particles. For an isothermal (298.15 K) discharge cycle between 3.5 and 0.136 MPa, the predicted net deliverable capacity is 114.0 (v/v)net for a monolith and 93.1 (v/v)net for a close-packed bed. If, however, the storage system is operated at 253 K, the net storage capacity of a monolithic block of MIL-53(Al) increases to a value that is very close to the DOE target of 150 (v/v)net.

Chrastil-Type Approach for Representation of Glycol Loss in Gaseous System

Glycols are generally used to adjust the water dew-point in natural gas processes to avoid gas hydrate/ice/condensate formation. Their vaporization loss in gaseous systems may happen regularly in the petroleum industry. Glycols have very low solubility in the gas phase and because of difficulty of the corresponding measurement, few sets of experimental data are available in open literature and may not be fully satisfactory. In a previous work, we performed thermodynamic consistency tests in order to prepare reliable data sets for modeling purposes. Application of four widely used correlations in supercritical fluid industry, including the original Chrastil, Adachi and Lu, del Valle and Aguilera, and Mendez-Santiago and Teja, in which the effects of temperature, density of gas (solvent), and pressures on the solubility of glycol are generally taken into account, are investigated to represent the corresponding solubility of ethylene glycol and triethylene glycol in supercritical methane and carbon dioxide b...

Water Solubility in Supercritical Methane, Nitrogen, and Carbon Dioxide: Measurement and Modeling from 422 to 483 K and Pressures from 3.6 to 134 MPa

A series of experiments to measure the water solubility in supercritical nitrogen and carbon dioxide have been conducted at experimental conditions up to 483 K and 134 MPa. The accuracy of the experimental procedure is verified by comparing the water content data of methane in the literature and our experimental data for the methane−water system. In addition, a fugacity−fugacity approach including the cubic-plus-association equation of state (CPA EoS) and a fugacity−activity approach based on the Peng−Robinson EoS and the Henry’s law model are incorporated to predict the water content data of methane, nitrogen, and carbon dioxide. A comparison between our experimental data, literature data, and the results of the fugacity−activity approach shows the reliability of the PR-Henry’s law model for the phase behavior studies of the nitrogen−water system over a wide range of pressure and temperature conditions. However, the CPA equation is not capable of reproducing the high pressure vapor and liquid phase compositions of the water−nitrogen system. The concept of cross-association satisfactorily improves the performance of the CPA equation of state in predicting the water content data of supercritical methane. On the basis of the literature and new measured data in this study, it has been found that the CPA equation better represents the phase behavior of the water−carbon dioxide system if carbon dioxide is considered as a self- and cross-associating molecule.

Kinetics of enzymatic synthesis of geranyl butyrate by transesterification in various supercritical fluids

The transesterification of methyl butyrate, ethyl butyrate and butyl butyrate to geranyl butyrate was investigated in supercritical carbon dioxide. The effect of chain length of the butyrate on the rate of transesterification was investigated. The initial rates followed the trend: ethyl butyrate < butyl butyrate < methyl butyrate. The transesterification of butyl butyrate to geranyl butyrate in various supercritical fluids such as ethylene, methane, ethane was also examined. The initial rate of transesterification of butyl butyrate in different supercritical fluids followed the order: ScCO 2 < ScC 2H 6 < ScC 2H 4 < ScCH 4. The highest initial rate was obtained in supercritical methane and the reasons for this observation were proposed. The Ping-Pong Bi–Bi model with inhibition by both acid and alcohol was used to model the experimental data and determine the kinetics of the reaction.

Recent advances in organometallic alkane and noble gas complexes

Abstract Fast time-resolved infrared (TRIR) spectroscopy has been useful for studying the reactions of a wide range of organometallic alkane and noble gas complexes at ambient temperature following irradiation of metal carbonyl precursor complexes. The reactivity of organometallic alkane and xenon complexes decreases both across and down groups V, VI, and VII, and for a given metal/ligand combination the alkane and xenon complexes have similar reactivities. Systematic studies of reactivity have produced long-lived Re complexes which have allowed such complexes to be characterized using NMR spectroscopy. A new approach using liquid propane at low temperature as a solvent to monitor the interaction of such weakly coordinating ligands with transition-metal centers is outlined. TRIR studies monitoring the coordination and activation of methane and ethane in supercritical methane and liquid ethane solvents at room temperature are also reviewed.

Measurement of the triethylene glycol solubility in supercritical methane at pressures up to 9 MPa

The solubility of triethylene glycol in supercritical methane was measured at temperatures of 298.15 and 316.75 K and pressures up to 9 MPa using a static saturation apparatus with volume displacement. The relative uncertainty of the experimental data amounts to less than ±12%. The data can be reproduced with reasonable accuracy using the generalized cubic Peng–Robinson as well as the Soave–Redlich–Kwong equations of state in combination with the quadratic mixing rule, whereas two temperature dependent binary interaction parameters were fitted for the referring system. The mean logarithmic deviation for the triethylene glycol solubility in methane is roughly 24.7% in case of the Peng–Robinson, but only 4.6% in case of the Soave–Redlich–Kwong equation of state.

Comments on “Measurement and Modeling of the Solubility of Water in Supercritical Methane and Ethane from 310 to 477 K and Pressures from 3.4 to 110 MPa”

We describe a new flow cell apparatus for measuring the water content of gases up to 120 MPa at 490 K that uses a combination of gravimetric and electrical resistance techniques to determine the solubility of water in the gaseous phase. The new experimental data for the solubility of water in supercritical methane and ethane were obtained with our apparatus spanning pressures from 3.4 to 110 MPa covering a temperature range from 310 to 477 K. We model the experimental results by combining two equations of state; vapor-phase fugacities and fugacity coefficients are calculated with a modified Peng−Robinson equation of state, and aqueous-phase fugacities are calculated using an equation by Wagner and Pruss (J. Phys. Chem. Ref. Data 2002, 31, 387−535) or by a modification of a correlation developed by Saul and Wagner (J. Phys. Chem. Ref. Data 1987, 16, 893−901). We compare the model results with new and existing experimental data and with commercially available simulators. Our model reproduces the experimenta...