Scaling carbon sequestration phenomena to the earth's surface

We present a computational framework for fast monitoring of fault stability and ground deformation in multiphase geomechanics and demonstrate its efficacy for a carbon sequestration--enhanced oil recovery case study. The staggered solution algorithm for the coupled problem is augmented with a feature that allows for the flow and geomechanics sub-problems to be solved on different unstructured tetrahedral grids. For the field scale problem, the geomechanics grid goes all the way to the free surface while the flow grid is truncated at a depth above which the layers are impermeable. This framework avoids the unnecessary computational burden associated with equilibrating the initial pressure solution in the overburden, allows for a study of the critical interaction between overburden and faults, allows for fast renditions of ground deformation, and allows a choice of resolution for the flow and geomechanics grids independently to capture disparate length scales of the underlying physics.

Numerical Identification of the Filtration Capacitive Parameters in Two-Phase Petroleum Reservoirs

We study initial and boundary value problem for nonlinear three dimensional two phase nonlinear filtration problem in three dimensional bounded regions. The reservoir is a two phase and three dimensional oil-water system that is been implemented with typical parallelepiped model. The reservoir constructed with different number of grid blocks in x, y and z directions and initialized with initial pressure, water saturation, corresponding fluid and rock properties in every grid block. To find approximate solution of the above mentioned problem we use finite difference method. We form solution’s algorithm of inverse problem for numerical parameter identification of the petroleum reservoir.

Theoretical study of the impact aimed at improving the efficiency of fiber cleaning

Since cotton cleaning in Uzbekistan is carried out mainly manually, this paper discusses the methods and technologies established in the process of cleaning cotton and fiber. The process of fiber cleaning is one of the important processes that complete the technological process of cotton processing, given that the quality of fiber largely depends on the efficiency of this process, the research work on the mechanization of the type of collection and improving the efficiency of its cleaning is analyzed. In order to improve the efficiency of cleaning cotton collected on the machine, information is provided on the need to improve the equipment for cleaning fiber used in cotton gins. The research results are based on the need to replace a special structural device that guides the fiber to the correct tooth of the first sawtooth cylinder located on two drum cleaning plants. New fiber-cleaning equipment was installed in the Jizzakh regional JSC “Zarbdor cotton cleaning» and experimental tests were conducted in production conditions. In addition, the process of changing the pressure, density and speeds in the furnace and the effect of their cleaning efficiency has been modeled and theoretically analyzed, when the efficiency of cleaning the cotton fiber flow using a column system allows changing the raw material from 4 mm to 15 mm based on the device. By results of the conducted analysis it was shown that the increase of efficiency of purification depends on the device attached to the saw teeth, factor of the taxation of the distribution coefficient B and p 0 efficiency factor of increasing the initial pressure and coefficient of efficiency savings from the analysis of graphs, which present graphs of the distribution depending on the type of saw teeth. Based on the results of the research, recommendations are given for the widespread introduction of fiber cleaning equipment installed at enterprises of primary cotton processing, with the installation of a special structural guide device.

Non-linear filtration models and the effect of nonlinearity parameters on flow rates in low-permeability reservoirs

Filtration of oil in low-permeable reservoirs is considered. The experimental data of dependence of filtration velocity on pressure gradient are analysed. It is shown that the filtration law in low-permeability reservoirs differs from the linear Darcy’s law and from the non-linear law with an initial pressure gradient. The power law of filtration in low-permeability reservoirs is experimentally substantiated. Models of nonlinear filtration influence on flow rate are proposed. The analysis of influence of nonlinear filtration parameters on flow rate in technogenically modified near-wellbore zone is carried out.

Shock Wave Propagation and Flame Kernel Morphology in Laser-Induced Plasma Ignition of CH4/O2/N2 Mixture

The application of laser ignition in the aerospace field has promising prospects. Based on the constant volume combustion chamber, the laser ignition of CH4/O2/N2 mixture with different initial pressure, different laser energy, different equivalence ratio and different oxygen content has been carried out. The development characteristics of the flame kernel and shock wave under different conditions are analyzed. In addition, the Taylor model and Jones model are also used to simulate the development process of the shock wave, and a new modified model is proposed based on the Jones model. The experimental results show that under pure oxygen conditions, the chemical reaction rate of the mixture is too fast, which makes it difficult for the flame kernel to form the ring and third-lobe structure. However, the ring structure is easier to form with the pressure and laser energy degraded; the flame kernel morphology is easier to maintain at a rich equivalence ratio, which is caused by the influence of the movement of hot air flow and a clearer boundary between the ring and the third-lobe. The decrease of the initial pressure or the increase of the laser energy leads to the increase in shock wave velocity, while the change of the equivalence ratio and oxygen content has less influence on the shock wave.

Числове дослідження змішування в системі генерації газової суміші

The subject of research is a gas-dynamic process of mixture formation with a given component mass fraction during overflow through the mixer nozzles in the mixture generation system. The aim of the study is the scientific and experimental evaluation of the mixer technical solutions to ensure the accuracy and homogeneity of the gas mixture. The current work conducts numerical study on the flow of a gas flow through the mixer nozzles of the mixture generation system, ensuring its stoichiometric component composition and homogeneity. The problem is solved by developing adequate mathematical models of gas-dynamic flow and analyzing the results of numerical simulations. The following results were obtained. A mixer with the nozzles in the mixture generation system has been created and a technical solution for its design has been scientifically substantiated. The areas of flow sections of mixer nozzles are experimentally established. A mathematical model of generating a mixture with a given component mass fraction was developed and a series of numerical experiments was conducted to study its overflow through the mixer. A 3D simulation was conducted using ANSYS CFX software. The stationary formulation of the problem is applied. In the nozzles of closed overflow of the mixer, the heat exchange of the gas flow with the walls is taken into account by solving a separate problem and determining the corresponding heat transfer coefficients. At the inputs to the mixer, the ratio of the initial pressure of the components of the mixture is determined, which ensures its stoichiometric composition. The fields of the gas flow velocities, the mass flow rate of the components of the gas mixture through the mixer, and pressure and temperature fields are obtained. Based on the simulation results, it was found that the design of the developed mixer ensures the creation of a gas mixture with a homogeneity of at least 3%. With a constant pressure ratio of the mixture components to the mixer inlet, the gas mixturedosing accuracy can be achieved at least 1%.

A site assessment tool for H2 storage in depleted hydrocarbon reservoirs

Hydrogen storage is a key component in realization of an emission free future. Depleted hydrocarbon reservoirs offer a low cost medium for large-scale hydrogen storage. While the effect of hydrogen in triggering some chemical and biochemical reactions has stablished some screening criteria to choose a suitable underground storage site according to reservoir geochemistry, there is no screening criteria based on the effect of variables such as pressure, temperature and composition of the residual hydrocarbon on hydrogen recovery. In this work, we first investigate the cost required for hydrogen compression in terms of the work required for compressors. Then we investigate the effect of reservoir pressure, storage pressure, reservoir temperature and residual composition on hydrogen recovery. Our results show that on one hand the work required for pressurizing hydrogen does not increase linearly with pressure, and on the other hand, hydrogen recovery increases with storage pressure. Additionally, Hydrogen recovery was shown to decrease by increase in reservoir initial pressure before hydrogen storage. Therefore, it seems that hydrogen storage will be more efficient if it is conducted at the highest possible pressure in a reservoir with low initial pressure (either a shallow reservoir, or a depleted reservoir). Our results did not show any strong relationship between hydrogen recovery and temperature. Hydrogen recovery showed to increase slightly with increase in residual hydrocarbon density. However, the effect of residual hydrocarbon was observed to be significant on purity of the produced hydrogen. In this sense, depleted black oil reservoirs seem to be the best and dry gas reservoirs the worst choice.

Highly efficient TiO2-supported Co–Cu catalysts for conversion of glycerol to 1,2-propanediol

Glycerol is a low-cost byproduct of the biodiesel manufacturing process, which can be used to synthesize various value-added chemicals. Among them, 1,2-propanediol (1,2-PDO) is of great interest because it can be used as an intermediate and additive in many applications. This work investigated the hydrogenolysis of glycerol to 1,2-PDO over Co–Cu bimetallic catalysts supported on TiO2 (denoted as CoCu/TiO2) in aqueous media. The catalysts were prepared using the co-impregnation method and their physicochemical properties were characterized using several techniques. The addition of appropriate Cu increased the glycerol conversion and the 1,2-PDO yield. The highest 1,2-PDO yield was achieved over a 15Co0.5Cu/TiO2 catalyst at 69.5% (glycerol conversion of 95.2% and 1,2-PDO selectivity of 73.0%). In the study on the effects of operating conditions, increasing the reaction temperature, initial pressure, and reaction time increased the glycerol conversion but decreased the selectivity to 1,2-PDO due to the degradation of formed 1,2-PDO to lower alcohols (1-propanol and 2-propanol). The reaction conditions to obtain the maximum 1,2-PDO yield were a catalyst-to-glycerol ratio of 0.028, a reaction temperature of 250 °C, an initial H2 pressure of 4 MPa, and a reaction time of 4 h.

Potential of hydrogen/diesel reactivity controlled compression ignition (RCCI) combustion from the perspective of the second law of thermodynamics

The potential of reactivity controlled compression ignition (RCCI) combustion fueled with hydrogen and diesel (i.e. hydrogen/diesel RCCI) was evaluated using multi-dimensional simulations embedded with a reduced chemical mechanism. In hydrogen/diesel RCCI, the premixed hydrogen is ignited by the diesel, which is directly injected into the cylinder well before the top dead center. To investigate the potential benefits of hydrogen/diesel RCCI, its combustion characteristics were compared with that of gasoline/diesel RCCI from the perspective of the second law of thermodynamics. Meanwhile, the impacts of premixed energy ratio and initial pressure on the exergy distribution for hydrogen/diesel RCCI were explored. The results show that hydrogen/diesel RCCI has an advantage over gasoline/diesel RCCI in the reduction of exergy destruction due to higher combustion temperature, shorter combustion duration, and the distinctive oxidation pathways between hydrogen and gasoline. A higher proportion of exergy output work can be achieved for hydrogen/diesel RCCI under the conditions with the same total input energy and 50% heat release (CA50) point. Moreover, a larger premixed energy ratio (i.e. larger hydrogen proportion) is helpful to elevate exergy output work and reduce exergy destruction owing to higher combustion temperature and the undergoing oxidation pathways of hydrogen with less exergy destruction. A higher initial pressure yields raised exergy destruction because of lower combustion temperature and longer combustion duration, but exergy output work is increased owing to the significantly reduced exergy transfer through heat transfer.

Improvement of Polytetrafluoroethylene Membrane High-Efficiency Particulate Air Filter Performance with Melt-Blown Media

Polytetrafluoroethylene (PTFE) membrane filters are widely used in low-load application areas, such as industrial cleanrooms, due to their low initial pressure drop. In this study, melt-blown (MB) nonwoven was introduced as a pre-filtration layer at the front end of a high-efficiency particulate air (HEPA) filter to improve the filter performance of the PTFE membrane. Pre-filtration reduces the average particle size, which reaches the PTFE membrane and reduces the dust load on the HEPA filters. A comparative analysis of the HEPA filters by composite MB and PTFE was conducted. Regarding the MB composite on the PTFE, low-weight and high-weight MB composites were effective in increasing dust filtration efficiency, and the dust loading capacity of the PTFE composite with high-weight MB increased by approximately three times that of the PTFE membrane. In addition, the filter was installed on an external air conditioner in an actual use environment and showed a high efficiency of 99.984% without a change in differential pressure after 120 days.