145 results about "Effective diffusion coefficient" patented technology

An apparatus for measuring the effective vapor diffusion coefficient of a test vapor diffusing through a sample of porous media contained within a test chamber. A chemical sensor measures the time-varying concentration of vapor that has diffused a known distance through the porous media. A data processor contained within the apparatus compares the measured sensor data with analytical predictions of the response curve based on the transient diffusion equation using Fick's Law, iterating on the choice of an effective vapor diffusion coefficient until the difference between the predicted and measured curves is minimized. Optionally, a purge fluid can forced through the porous media, permitting the apparatus to also measure a gas-phase permeability. The apparatus can be made lightweight, self-powered, and portable for use in the field.

The invention discloses a shale gas reservoir gas diffusion coefficient experiment test method. According to a method, a one-dimensional diffusion mathematic model is built by monitoring pressure attenuation data in a shale plunger rock sample under effective stress conditions of methane gas with a certain initial pressure in a constant-temperature closed system with the micro-pore structure and the gas existence state of a shale reservoir as bases, the diffusion coefficient of the gas (methane) in shale is calculated, and the diffusion mass-transfer capacity of the gas (methane) in the shale is quantitatively assessed. In the experiment testing process, the diffusion process of gas in the shale gas reservoir can be effectively simulated, and influences of effective stress, gas adsorption/desorption and other factors on the diffusion coefficient are reflected. Besides, the method can overcome influences of gas free expansion stage data in a traditional adsorption/desorption method on the diffusion coefficient. The method can assess the diffusion mass-transfer capacity of the gas in the shale and provide experiment support for researches in the aspects of shale gas reservoir productivity models, productivity prediction and the like.

The invention discloses a preparation method for a novel heavy oil hydrogenization demetallization catalyst adopting macroporous structures. The preparation method is characterized by particularly comprising the following steps: 1) preparing alumina sol; 2) mixing pitch residue powder with the alumina sol to prepare a catalyst carrier adopting the macroporous structures; 3) impregnating the formed catalyst carrier by a two-step impregnation method adopting isopyknic division to finally obtain the catalyst. The catalyst prepared by the method adopts mesopore structures and the macroporous structures at different proportions; the proportion of the macroporous structures can be adjusted with the amount of pore forming materials of pitch residues. A diffusion experiment shows that the catalyst adopting the macroporous structures in a certain proportion meets mechanism of a heavy oil hydrogenization demetallization reaction, has a relatively high metal accommodation ability, effectively lowers the reaction resistance in the heavy oil hydrogenization demetallization reaction process, improves effective diffusion coefficient of heavy oil in the catalyst, and is suitable for processing heavy oil or residual oil with relatively high metal content.

The invention relates to a method for measuring a diffusion coefficient of carbon dioxide in a saturated oil core. The method comprises the following steps of: performing nondimensionalization by using a convection-diffusion mathematical model, and performing numerical solution, wherein the diffusion coefficient Deff of the carbon dioxide in the saturated oil core is finally obtained by using the method and required to be used in the numerical solution process; and continuously correcting the value of D'eff, and repeatedly executing the step (13), so a curve c of delta Co and t<1/2> is completely coincided with a curve b of delta PTh and the t<1/2>, wherein the D'eff is the Deff and represents the diffusion coefficient of the carbon dioxide in the saturated oil core. The method has the advantages that the influence of the volumetric expansion of crude oil caused by dissolution of the carbon dioxide in the crude oil on the diffusion process and the influence of a porous medium on the diffusion process are taken into consideration, and the obtained effective diffusion coefficient of the carbon dioxide in the saturated oil core can accurately reflect the true diffusion process.

The invention discloses a combined measurement method for organic matter-rich compact rock core gas permeability and diffusion coefficient. The method utilizes a gas pressure attenuation device to accomplish. The device is composed of a rock core holder, a gas storage chamber, a vacuum pump, a confining pressure pump, and a computer. The rock core holder is connected to the vacuum pump and the confining pressure pump respectively, the inlet end of the rock core is connected to the gas storage chamber and a gas source, the outlet end of the rock core is in a closed state, and the device is located in a water-bath heating system. By monitoring the process of the gas in the gas storage chamber flowing to the rock core till balance, a gas pressure attenuation curve can be obtained, then according to a real gas state equation, material balance and the occurrence and flow mechanism of gas in rock, the attenuation curve is divided into a seepage stage and a diffusion stage, thus acquiring the gas permeability and diffusion coefficient. The method provided by the invention simplifies the testing procedure, improves the experimental analysis efficiency, and can provide data support for experimental evaluation of gas mass-transfer ability in shale, coal rock and other unconventional reservoir rocks, gas well productivity prediction and the like.

A method for measuring the effective diffusion coefficient and the porosity of a porous medium includes steps as follows: using an evaporation tube method to measure the binary gas diffusion coefficient DAB of component A in component B and the effective diffusion coefficient DABP of component A in the measured porous medium, utilizing the relation between DAB and DABP to work out the ratio epsilon/tau of the measured porous medium porosity to the tortuosity factor, and obtaining the porosity of the measured porous medium according to the tortuosity factor tau. The invention has the advantageof rapidly and accurately measuring the porosity of the porous medium and the effective diffusion coefficient of a gas in the porous medium, thereby providing conditions for chemical engineering and scientific research practice.

The invention discloses a method for detecting diffusion coefficient of coal bed gas in coal matrix. The method comprises the following steps: keeping temperature in a sealed and diffused chamber to rated temperature; suspending coal matrix in the sealed and diffused chamber; detecting the air pressure of coal bed gas at each moment in the sealed and diffused chamber; judging whether the air pressure of coal bed gas is rated air pressure; if the air pressure of coal bed gas is lower than the rated air pressure, injecting the coal bed gas into the sealed and diffused chamber by a sealed conduit to cause the air pressure of coal bed gas in the sealed and diffused chamber to reach the rated air pressure; recording the amount of the coal bed gas injected into the sealed and diffused chamber at each moment; and according to the rated temperature, the rated air pressure and the amount of the coal bed gas injected into the sealed and diffused chamber at each moment, calculating the diffusion coefficient of the coal bed gas in the coal matrix. The technical scheme of the invention can detect the diffusion coefficient of the coal bed gas in the coal matrix, which is much closer to the true value compared with the prior art.

The invention relates to a test method and a test device for obtaining saturated solubility and diffusion coefficients of a solid solute in a liquid phase simultaneously. According to solute mass conservation law and Archimedes law in the process of dissolution, a physical model in the process of dissolving the solid solute is established and mathematical description of the physical model is determined so as to establish an experiment characterization method and a measurement device. In the test method and the test device, the saturated solubility and the diffusion coefficients of the solid solute in the liquid phase at a certain temperature and under certain pressure are calculated from the measured real-time dissolved amount through a specific inversion model (physical and mathematical model). The test device has the advantages of simple operation, short measuring time and capability of measuring large quantity of data; and the solubility and the diffusion coefficients are obtained simultaneously, and the measured data can be verified mutually, so the measuring accuracy is improved and the data consistency is ensured well.

Description is provided herein for an embodiment of a method determining a hematocrit-corrected glucose concentration. The exemplary method includes providing a test strip having a reference electrode and a working electrode, wherein the working electrode includes a plurality of microelectrodes and is coated with at least an enzyme and a mediator. The method can be achieved by: providing a test strip comprising a reference electrode and a working electrode formed with a plurality of microelectrodes and coated with a reagent layer; applying a fluid sample to the test strip for a reaction period; applying a test voltage between the reference electrode and the working electrode; measuring a test current as a function of time; measuring a steady state current value when the test current has reached an equilibrium; calculating a ratio of the test current to the steady state current value; plotting the ratio of the test current to the steady state current value as a function of the inverse square root of time; calculating an effective diffusion coefficient from the slope of the linearly regressed plot of the ratio of the test current to the steady state current value as a function of the inverse square root of time; and calculating a hematocrit-corrected concentration of analyte.

The invention discloses an apparatus for measuring a diffusion coefficient during a shale oil carbon dioxide huffing-puffing process and a method thereof. According to the invention, a radial rock core holding unit, a confining pressure pump and a first pressure transducer are connected with a first three-way connector, a simulation oil saturation pump, a third pressure transducer and the radial rock core holding unit are connected with a fourth three-way connector, the radial rock core holding unit and a vacuum pump are communicated with outside through a third three-way connector, the radialrock core holding unit and a CO2 high-pressure container are connected, the CO2 high-pressure container, a second pressure transducer, and a CO2 gas tank are connected with a second three-way connector, and the confining pressure pump, the CO2 high-pressure container, the radial rock core holding unit, the simulation oil saturation pump, the first pressure transducer, the second pressure transducer, the third pressure transducer, the first three-way connector, the second three-way connector, the third three-way connector, and the fourth three-way connector are capable of controlling the temperature through a thermotank. The CO2 adsorption dissolving by shale and diffusion coefficient under crude oil expansion condition are considered, so that the apparatus and the method have important guidance meaning for designing an on-site exploitation scheme.

The invention discloses a device and method for measuring the diffusion coefficient of gas in a porous medium by applying CT (computed tomography), and belongs to the technical field of oil production engineering. The device comprises a CT imaging system and a CO2 diffusion system, wherein the CT imaging system comprises a universal X-ray CT device and a data processing computer; the CO2 diffusion system comprises a high-pressure container, a gas injection pump, a gas bottle, a gas injection pump temperature control device, a high-pressure container temperature control device, a vacuum pump, a pressure sensor and a temperature sensor; the high-pressure container is placed in the CT device; an inlet of the high-pressure container is connected with the gas bottle through the gas injection pump. During measurement, the CT device is used for obtaining a CT image in the high-pressure container, and a signal value of the CT image is used for analyzing changes in the concentration of carbon dioxide in a saturated oil porous medium, and calculating the diffusion coefficient of carbon dioxide in the saturated oil porous medium. According to the method and the device, understanding to the diffusion rules of a gas phase and an oil phase is enhanced, and basic physical property data is provided for researches on the diffusion process of gas and liquid in the porous medium.

The invention provides a molecular-dynamics simulation method of predicting a diffusion coefficient of a combustion process of a nano-multilayer film. The method comprises the following steps: 1) constructing a nano-multilayer-film molecular-dynamics simulation model, and exporting a configuration file; 2) completing a control file; 3) using a molecular-dynamics method to calculate and output mean-square-displacement (MSD) data of each component; 4), drawing the MSD data as a curve of MSD versus step length; 5) calculating a slope of the MSD versus time; and 6), obtaining the diffusion coefficient by solving according to Einstein's law. According to the method, solving is carried out for the diffusion coefficient of each component of the nano-multilayer film, the problem that real-time atomic diffusion behaviors of the self-propagating reaction combustion process of the nano-multilayer film cannot be tested and analyzed by experiment means is solved, difficulty of program compilation is significantly reduced, atomic behaviors and processes of nano-connection are more accurately understood, and a reference is provided for structure design of nano-multilayer films through study on diffusion coefficients and diffusion behaviors of the multilayer films of different atomic proportions under different temperatures.

The invention discloses a method for measuring diffusion coefficient of carbon dioxide in rock. In the invention, the diffusion coefficient of carbon dioxide in rock is not measured by measuring the concentration of carbon dioxide, but obtained by measuring the pressure variation of carbon dioxide gas: the concentration variation is recalculated by using a corrected carbon dioxide gas state equation, thereby determining the diffusion coefficient of carbon dioxide gas in rock. The invention basically discards gas chambers, eliminates the influence of sampling on gas pressure, and integrates the process of vacuumizing, saturated formation fluid and gas diffusion coefficient determination, thereby thoroughly eliminating the influence on saturated fluid in rock in the vacuumizing process.

The invention discloses a method for calculating an effective utilization coefficient of irrigation water in a vine-with-melon irrigation area. According to the method, on the basis of the water balance principle as well as characteristics of various water source project types, complex multi-water-source multi-user dispatching, and vertically and horizontally staggered subareas for water transport and distribution, small-reservoir water level observation is carried out and an irrigation water amount provided by retaining and rainfall as well as overland runoffs are calculated, so that the accuracy of calculation of sgross irrigation water amount of the irrigation area can be improved. In addition, the invention also discloses another method for calculating an effective utilization coefficient of irrigation water in a vine-with-melon irrigation area. Losses of all water sources during the conveying process are considered respectively and then weighting is carried out to obtain an effective utilization coefficient of irrigation water in an irrigation area. The two kinds of methods can be applied to large and medium-sized irrigation areas with complex water sources, thereby providing the basis for promoting vigorously agricultural water saving and water-saving irrigation.

The invention discloses a device for testing the performance of a cohesive soil sample. The device comprises a sample box, an upper permeable stone, a lower permeable stone, upper filter paper, lower filter paper, a micro differential pressure sensor, a data acquisition instrument, a precision injection pump, a first liquid storage tank, a second liquid storage tank, a third liquid storage tank and a fourth liquid storage tank, wherein an upper left way pipe, an upper middle way pipe and an upper right way pipe are provide in a top cover, a lower left way pipe, a lower middle way pipe and a lower right way pipe are provide in a pedestal, the micro differential pressure sensor is connected with the data acquisition instrument, and four injectors are arranged in the precision injection pump. The testing device can carry out determination of the coefficient of membrane efficiency, the coefficient of effective diffusion and the performance of retardation factors on the cohesive soil sample. Meanwhile, the invention also provides a testing method used by the device for testing the performance of the cohesive soil sample, and the method is simple and practicable and can realize combined determination of the coefficient of membrane efficiency, the coefficient of effective diffusion and the performance of retardation factors of the cohesive soil sample instead of respective determination, thereby improving determination efficiency.

The invention discloses a method for detecting the diffusion coefficient of water vapor in a bituminous mixture. The method comprises the following steps: forming a to-be-detected cylindrical bituminous mixture sample; placing the sample in a closed chamber, and testing the mass of the sample in vacuum and at a test temperature by a magnetic levitation weight balancing system; calculating the saturated vapor pressure of the water vapor at the test temperature through the Antoine equation, obtaining the vapor pressure required in a reaction chamber under a relative humidity condition of the corresponding test through further calculation, inputting the vapor pressure value, setting the test temperature, and detecting the mass of the sample constantly; testing the change of the vapor adsorption of the sample along with time under the conditions of various specific test temperatures and relative humidity gradient conditions, and obtaining a water vapor diffusion coefficient through formula fitting. Tests of the diffusion coefficient of the water vapor in the bituminous mixture at different temperatures and multiple relative humidity gradients can be realized with the method; the test progress can be accelerated effectively and the test time can be shortened when the tests are performed at negative pressure. The method receives little interference from environmental factors and is high in test precision.

The invention relates to a device for measuring a diffusion coefficient of CO2 diffusing from an aqueous phase to an oil phase. The device comprises a CO2 gas source, a distilled water source, a U-shaped high-temperature high-pressure visual diffusion device and a crude oil source which are sequentially and vertically connected in parallel to a pipeline, wherein a steel separator is vertically arranged in the U-shaped high-temperature high-pressure visual diffusion device; the interior of the U-shaped high-temperature high-pressure visual diffusion device is separated into a left-side space and a right-side space of which the bottoms are communicated by virtue of the steel separator; a temperature measuring point, a pressure measuring point and a lower outlet are formed in the bottom in the U-shaped high-temperature high-pressure visual diffusion device; and the device also comprises a pressure collection system, a return pressure gas tank, a heater and a temperature control system. The device disclosed by the invention is reliable in principle and easy and convenient to operate, the influence caused by oil-gas-water density difference is overcome, a pressure drop method for measuring the gas-liquid two-phase diffusion coefficient is applied to measuring the diffusion coefficient of gas between the aqueous phase and oil phase, the CO2 concentration change and experimental equilibrium pressure do not need to be measured, and the diffusion coefficient of CO2 diffusing from the aqueous phase to the oil phase can be solved.

The invention discloses an experimental device for testing a diffusion coefficient and an osmotic coefficient of an unsaturated dielectric gas. The device mainly comprises a gas-supplying device, a main body reaction device and an outlet gas processing device. The gas-supplying device comprises a water-bath heating device for heating transmitted gas, simulating the temperature generated by landfill refuse degradation and temperature variation generated by the external temperature change; the main body reaction device is composed of three parts of a lower chamber, a middle chamber and an upperchamber, which are used for simulating refuse landfill gas, landfill covering soil (or GCL) and soil sample upper environment. The upper part is loaded to a porous stainless steel plate through an aircylinder to apply pressure to a soil sample (or GCL), so as to simulate the soil pressure at the upper part of the landfill covering soil (or GCL). The outlet gas collecting device is mainly composedof a gas collecting bottle, can be used for collecting and treating the gas after reaction, and the situation that the gas after experiment pollutes the air is avoided. The device is simple in structure and wide in application range.

The invention relates to a spectral data processing method. The spectral data processing method comprises the following steps: (A1) exciting a standard sample, collecting a spectrum of the standard sample, and determining whether a relative standard deviation of the standard sample spectrum is in a first threshold range or not; (A2) determining peaks with wave peak intensity smaller than a saturation threshold value of a detector and wave peak pure intensity greater than a second threshold value in the standard sample spectrum as effective peaks, and calculating a peak area of the effective peaks; (A3) calculating an effective coefficient, wherein the effective coefficient is a ratio of the peak area of the effective peaks in an original spectrum to the peak area of the effective peaks in the standard sample spectrum; (A4) performing polynomial fitting according to the effective coefficient and a pixel position of the corresponding effective peak, and obtaining a fitting curve of the effective coefficient and the pixel position relation: Coef=p1*i3+p2*i2+p3*i+c; and (A5) exciting a sample to be detected, and by virtue of the fitting curve, correcting an exciting spectrum as: Measureint.[i]=Coef[i]*Measureresa.[i]. The spectral data processing method has the advantages of convenience in operation, low cost, single standard sample correction and the like.

The present invention provides a new method to obtain an effective diffusivity for a certain substance in solutions that diffuse through a porous material. The porous material initially separates two solutions that are different in concentration of the substance. The concentration gradient gives rise to diffusion through the porous material, The concentration change of the substance in the low-concentration compartment is detected through a measurement of the electrochemical impedance data. By means of the measurement, an effective diffusivity coefficient of the substance through the porous material is calculated.

The invention provides a device and a method for detecting the rock diffusion coefficient based on micro-differential pressure automatic injection. The device comprises a natural gas source, a nitrogen source, a first multiplication supercharger, a second multiplication supercharger, a differential pressure sensor, a confining pressure tracing pump, a boosting injection pump, a first displacement transmitter, a second displacement transmitter and a core clamp, wherein one end of the first multiplication supercharger is connected with the natural gas source and connected with a first diffusion chamber, and the other end of the first multiplication supercharger is connected with the boosting injection pump; one end of the second multiplication supercharger is connected with the nitrogen source and connected with a second diffusion chamber, and the other end of the second multiplication supercharger is connected with the boosting injection pump; and the confining pressure tracing pump is connected with the core clamp between the first diffusion chamber and a second diffusion chamber. According to the embodiment of the invention, the problem of inaccurate measurement result caused by existence of the pressure difference between two diffusion chambers can be solved, the whole process of diffusion injection can be operated automatically, errors caused by manual operation can be reduced, and the measurement result accuracy can be effectively improved.

The invention discloses a method for obtaining chlorine ion diffusion and combination parameters in a cement-based material. The method only needs a total chlorine ion concentration curve, and can simultaneously obtain a chlorine ion effective diffusion coefficient and adsorption isothermal curve parameters through regression calculation. The method comprises the following steps: obtaining a total chlorine ion concentration distribution curve by a non-steady state diffusion test; trying different combinations of to-be-obtained parameters, calculating to obtain a theoretical total chlorine ion concentration distribution curve; carrying out fitting regression of the theoretical curve and the experimental curve by a nonlinear least square method, to obtain a set of parameter values with the highest fitting degree; calculating the confidence interval of each parameter; and further calculating to obtain an adsorption curve, distribution curves of an apparent diffusion coefficient along with the time and space, and distribution curves of total chlorine ions, combined chlorine ions and free chlorine ions in the time and space. The method not only can obtain the diffusion parameter and the combination parameter, but also can obtain the intervals of the parameters.

The method includes: providing a test strip comprising a reference electrode and a working electrode coated with a reagent layer; applying a fluid sample to the test strip for a reaction period; applying a test voltage between the reference electrode and the working electrode; measuring a test current as a function of time; measuring a steady state current value when the test current has reached an equilibrium; calculating a ratio of the test current to the steady state current value; plotting the ratio of the test current to the steady state current value as a function of the inverse square root of time; calculating an effective diffusion coefficient from the slope of the linearly regressed plot of the ratio of the test current to the steady state current value as a function of the inverse square root of time; and calculating a hematocrit-corrected concentration of analyte.