Effects of hot nanofluid injection on oil recovery from a model porous medium

Peer reviewedPostprin

Effects of temperature and nanofluid type on the oil recovery from a vertical porous media in antigravity fluid injection

Peer reviewe

A Precise Mathematical Correlation to Estimate Product Yield of Delayed Coking Units

Typical models are employed to estimate the product yields of delayed coking units using complicated and multistep calculations. In current study, a new first-order mathematical model have been proposed to estimate delayed coking products yield utilizing the Volk’s model as the baseline. The modified coefficients of Volk's model for industrial level are 0.634, 0.589, 1, and 1.116 for gas, gasoline, gasoil, and coke yield prediction, respectively. In Compare to other models, the proposed model showed very close and similar trend with industrial data in yield prediction, and the average error for gas production was 0.25%. For the gasoline, almost all of the other models have overestimated efficiency. However, current model prediction was obtained close to the industrial data with average error of 14 % that is almost three times better than the Volk’s model prediction (which was the most accurate model previously). The industrial data for the gasoil was underestimated by all previous models. However, the average error of proposed model for prediction of gasoil yield was 13% while other models’ estimation error is much higher. For the coke production, this newly developed model is the most accurate one compared to other predictive models

Numerical simulation of interfacial flows in micropores

Recent technological developments in microfluidics and fuel cells have given special significance to interfacial dynamics in small pores. Using a diffuse-interface model and a finite-element code, I have simulated three associated problems numerically: gas-liquid flow regimes in micropores; relative permeability for two-phase flow through a model porous medium; and dynamics of sessile drops under the simultaneous action of a wettability gradient and an external flow. For two-phase flows in corrugated microchannels driven by a pressure drop, a number of flow regimes were observed: gas flow, blockage, liquid flow, bubble-slug flow, droplet flow, annular flow and annular-droplet flow. Some of the regimes are known from prior studies in macroscopic pipes, but the others are new and specific to the micropores. Then a map of flow regimes has been constructed in the plane of the liquid saturation and the imposed pressure drop. The transitions among certain flow regimes show significant hysteresis, largely owing to the pinning of the interface at sharp corners in the flow conduit. As an extension of the above study, I computed the relative permeability of a model porous media made of corrugated tubes, using an averaging scheme over a pore-size-distribution of a real porous medium. I discovered that the flow rates vary nonlinearly with the pressure gradient, and that the extended Darcy's law does not hold in general. In the third project, I found that for each prescribed wetting gradient, there is a narrow range for the cross flow within which a stationary drop can be achieved. The drop motion exhibits strong hysteresis, i.e. sensitivity to initial conditions and forcing history. Two drops merge or separate depending on the competition between wettability and external flow. In general, the wettability gradient favors catch-up and coalescence while the external flow favors separation. These numerical simulations have demonstrated that novel interfacial dynamics can be produced in micropores where capillary forces and contact line dynamics play more important roles than in larger spatial dimensions. The numerical results may serve as guidelines to future experiments and technological development in microfluidics and lab-on-chip devices.Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat

Relative permeability for two-phase flow through corrugated tubes as model porous media

We report finite-element simulations of gas\u2013liquid two-phase flows through a model porous medium made of corrugated tubes. By resolving the pore-scale fluid dynamics and interfacial morphology, we compute the relative permeability of the porous medium by averaging over a pore-size-distribution of a real porous medium. A constant pressure gradient is applied on both fluids to simulate a pressure-driven creeping flow, and a diffuse-interface model is used to compute the interfacial evolution and the contact line motion. We observe a number of flow regimes in the micro-pores, depending on the pore size, imposed pressure gradient, and other geometric and physical parameters. The flow rates vary nonlinearly with the pressure gradient, and the extended Darcy\u2019s law does not hold in general. The interaction between the two phases, known as viscous coupling, is a prominent feature of the process. As a result, the relative permeability depends not only on saturation, but also on the capillary number, viscosity ratio, wettability of the solid wall, pore geometry, and the initial configuration. The effects of these factors are explored systematically and compared with previous studies.Peer reviewed: YesNRC publication: Ye

Interfacial flows in corrugated microchannels: flow regimes, transitions and hysteresis

We report simulations of gas-liquid two-phase flows in microchannels periodically patterned with grooves and ridges. A constant effective body force is applied on both fluids to simulate a pressure-driven creeping flow, and a diffuse-interface model is used to compute the interfacial evolution and the contact line motion. Depending on the body force, capillary force and the level of liquid saturation, a number of flow regimes may appear in the corrugated microchannel: gas flow, blockage, liquid flow, bubble-slug flow, droplet flow, annular flow and annular-droplet flow. A map of flow regimes is constructed for a set of geometric and flow parameters starting from a prescribed initial configuration. Some of the regimes are new, while others have been observed before in straight tubes and pipes. The latter are compared with previous experiments in terms of the regime map and the holdup ratio. The transition among flow regimes shows significant hysteresis, largely owing to the pinning of the interface at sharp corners in the flow conduit. Hysteresis is reduced if the sharp corners are rounded. Under the same operating conditions, different flow regimes can be realized from different initial conditions. The roles of geometry and wettability of the channel walls are also elucidated. \ua9 2011 Elsevier Ltd.Peer reviewed: YesNRC publication: Ye

Application of oak powder/Fe 3 O 4 magnetic composite in toxic metals removal from aqueous solutions

In this study, the capability of a magnetic composite of oak powder/Fe 3 O 4 (OP/Fe 3 O 4 ) for the adsorption of lead, cobalt, and nickel ions from aqueous solutions was examined. Characteristics and structure of oak powder (OP) and OP/Fe 3 O 4 magnetic composite were explored by FTIR, SEM, TGA-DTG, VSM, and XRD analysis. The XRD results showed that OP/Fe 3 O 4 magnetic composite and OP were in crystalline form. Kinetic behavior of adsorption process was studied using pseudo-first-order, pseudo-second-order, and Elovich models. Results indicated that the pseudo-second-order model (R 2 > 0.999) can better describe the kinetic behavior of the metal adsorption process. Equilibrium behavior of the adsorption process was also tested using Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Scatchard isotherm models. The results revealed that the adsorption equilibrium data for three metals match with the Freundlich isotherm model (R 2 > 0.99). This indicates the effectiveness of heterogeneous surfaces in comparison with homogeneous ones in the adsorption process of metal ions. Moreover, the results showed that the adsorption process of metal ions with the OP/Fe 3 O 4 magnetic composite is physical. Finally, negative values of enthalpy and entropy indicated that the process of the metal ion adsorption is spontaneous and exothermic