Effect Of Capillary Forces Research Articles

An adaptive and fast emulsion separation Janus membrane

Inspired by the capillary effect in nature (such as water transport in soils) and droplet-drive performance of Nepenthes, a new driving strategy for emulsion separation membrane based on the synergistic effect of capillary force and progressive wettability-induction force was proposed. It is prepared by a one-step, simple continuous, electrospinning process. By adjusting solutions and spinning parameters, the membrane obtains its capillary structure and progressive oleophilicity in one-step preparation. Attractively, the membrane shows separation efficiency and excellent permeability, with a flux of 384801 L m−2 h−1 bar−1 for the oil-water mixture, and the little water content of less than 18 ppm. And for emulsions, the flux even reaches 50000 L m−2 h−1 bar−1 and the separation efficiency reaches 99.95%. Furthermore, the membrane has excellent mechanical-stability: at 80 kPa transmembrane pressure, it can still effectively prevent water's penetration. Drawing inspiration from nature, the incorporation of capillary force and progressive wettability-induction force into the separation membrane as an additional dual emulsion separation driving force proves to be a highly effective and versatile approach. This method provides a way to solve the general flux-efficiency balance problem of oil-water separation and also provides a new strategy for the preparation of separation membranes for various purposes.

Analysis of asynchronous/inter-fracture injection-production mechanism under the condition of five-spot vertical and horizontal well combination in low permeability oil reservoirs

At present, low permeability resources are the focus of the development of petroleum industry. In this paper, firstly, the oil displacement mechanism under the condition of vertical and horizontal well combination is clarified. Secondly, the difference of the mechanism of enhancing oil recovery between asynchronous and inter-fracture injection and production is revealed. Thirdly, the difference of energy supplement mechanism between huff and puff and displacement is compared and analyzed. Results show that: (a) with asynchronous injection-production development, the oil saturation drop around the water injection well is greater than that of periodic injection-production and synchronous injection-production. (b) Under the dual effects of water injection pressure difference and capillary force, part of the injected water enters the reservoir with relatively small pore channels, expanding the swept volume. (c) In the soak stage of asynchronous injection-production development, capillary force is the main control factor of oil-water permeability, and its size determines the permeability level. (d) The injected water first flows through the large channel and then flows into small channel to complete the imbibition and replacement. (e) The flow field of asynchronous injection-production has a large sweep range, which is conducive to improving oil recovery.

Experimental Study on Convection Heat Transfer of CO2 in C/SiC Composite Porous Material at Subcritical, Transcritical, and Supercritical States

Using C/SiC as the structure for transpiration cooling is prospective for new hypersonic vehicles, based on clarification of heat transfer process in porous media. But there are still gaps due to the complexity of pore structure of C/SiC, together with the effects of capillary force and strong variation of thermophysical properties for subcritical and supercritical flow. In this study, heat transfer analysis for C/SiC with CO2 as the coolant is presented by experiments. Heat transfer characteristics in typical C/SiC sample under various mass flow rates (0.003–0.018 kg/s), inlet fluid temperatures (20–40 °C) and pressures (5.9–10 MPa) are analyzed. Heat transfer and pressure drop correlations have been developed. The results show heat transfer coefficient at supercritical state behaves non-monotonic under varying flow rates caused by the combined effect of sharp increase of specific heat and the change of flow rate. The effect of pressure on heat transfer can be neglected compared to that of flow rate, while for Reynolds number (Re) >100, the pressure drop of supercritical cases are smaller than that of phase-change cases under similar Re, due to the effect of capillary force in C/SiC. This study can provide basic support for further study of transpiration cooling using C/SiC and CO2.

Numerical Simulation of Fracturing Fluid Storage in Shale Reservoirs Based on Experimental Measurements of Stress Sensitivity of Hydraulic Fracture Network Conductivity

Hydraulic fracturing is used in shale reservoir production, with low flowback rates and a large amount of fracturing fluid retained inside the reservoir. In this study, a stress sensitivity analysis experiment on the fracture inflow capacity was implemented to investigate the relationship between the hydraulic fracture (HF) and natural fracture (NF) inflow capacities and effective stress. A three-dimensional shale reservoir model was also constructed to couple the experimentally obtained laws with the numerical model to investigate the effects of the connection and closure of the fracture network on the retention of the fracturing fluid. The results show that the stress sensitivity of natural fractures is two orders of magnitude higher than that of hydraulic fractures. The seepage-absorption effect of capillary forces is not the whole reason for the large amount of fracturing fluid retention. The closure of the fracture network formed by natural and hydraulic fractures during the production process led to the storage of a large amount of fracturing fluid, and this process maintained the stability of the water production rate during the steady water production period.

Interplay of fluid rheology and micro-patterning toward modulating draining characteristics on an inclined substrate

We investigate a gravity-driven thin film flow of a non-Newtonian liquid over an inclined micro-patterned surface. We demonstrate the effect of micro-patterning on the film draining rate and the velocity profile by varying the relative slit width (Tr) and the length of the periodic irregularities (L). We unveil the interplay of the substrate structure and the fluid rheology by modeling the non-Newtonian thin film using the Carreau model, and the rheology of the film is varied for different values of power index n. Through numerical simulations, we delineate the effects of inertia, viscous, and capillary forces on the physics of thin film flow. We report a significant augmentation of flow velocity for both shear-thinning and shear-thickening fluids as a result of substrate micro-patterning, with the relative slit width playing a dominant role while the length of the periodic irregularities has only a minor influence on drainage characteristics. However, when the sole effect of fluid rheology is considered, flow velocity enhances for pseudoplastic fluid and decreases for dilatant fluid in comparison to Newtonian fluid. We examine the combined effect of rheology and substrate topography, revealing the dominating influence of micro-patterning at high slit-widths, while the fluid rheology has a greater role to play at lower slit-widths. We also demonstrate that the susceptibility of flow physics on varying rheology or topography is greatest for low viscosity liquids. Finally, we mark different regimes where the augmentation of average velocity and surface velocity are individually achieved. Hence, we propose a suitable combination of substrate structure and fluid rheology to engineer a flow characteristic. Based on the suitability for various applications, we provide the key to simultaneously optimizing the fluid rheology and substrate micro-patterning for precise engineering and controlling the draining characteristics of a thin film.

Self-Adaptive Rapid Thermal Conductive Fabrics Based on Hygroscopic Shrinkage Response for Personal Cooling and Drying.

Advanced fabrics with thermal wet management capability as low energy consumption media contribute to personal cooling and drying. Nevertheless, it remains a great challenge to obtain intelligent fabrics with adjustable thermal conductivity (TC) capable of bridging the supply and demand between human body temperature and self-adaptive thermal conduction. Herein, we report hygroscopic-shrinkage nanofiber-based fabrics with excellent moisture sensitivity and significant volume shrinkage, which benefits the construction of high-density thermal conductive pathways by absorbing sweat, with a maximum sweat absorption rate reaching up to 1781%. The TC of the shrunken fabric is significantly increased from the initial 0.102 to 0.731 W·m-1 K-1 with a volume shrinkage rate of 89% due to the synergistic effect of van der Waals force, capillary force, viscous resistance, and gravity. Besides, an enhanced TC of the resulting fabrics facilitates rapid heat transfer to the environments. By capturing the surface temperature variations of the fabric after shrinkage and commercially available cotton/Coolmax, we obtained the fabric that releases the same amount of heat in a shorter period of time (3.3 s). With its exceptional personal thermal and wet management properties, this study paves the way for designing new-generation intelligent fabrics capable of creating more comfortable microclimates.

Pore size optimization and fluid channel analysis of composite wick and anti-gravity study

Flat plate micro heat pipes (FPMHPs) utilize the vapor–liquid two-phase circulation of the working medium to transfer heat and play an essential role in heat dissipation systems. But the effects of capillary force and porosity on the flow channel’s heat transfer characteristics and the working medium’s anti-gravity properties are not clarified. It is found in the heat transfer theory that balancing the capillary force and porosity of the composite wick can improve heat transfer efficiency, increase the maximum thermal power and anti-gravity of the FPMHP. FPMHPs with composite wicks of different pore sizes were developed and tested by the established test platform. The results indicated that the capillary force and porosity of the composite wick constrained each other, and the FPMHP made of the composite wick sintered with 80 mesh copper powder (CW80-FPMHP) had the best heat transfer characteristics and anti-gravity properties. The maximum thermal power of CW80-FPMHP is 38.6 W at 0°, which is 5.4%, 3.6%, 3.5% and 17% higher than that of CW60-FPMHP, CW70-FPMHP, CW90-FPMHP and CW100-FPMHP, respectively. At a tilt of 45°, the maximum thermal power of CW80-FPMHP is 26.27 W, which is 17.6%, 24.3%, 53.9%, 53.9%, and 51.8% higher than CW60-FPMHP, CW70-FPMHP, CW90-FPMHP, and CW100-FPMHP, respectively. In addition, the thermal resistance of the vapor channel in CW80-FPMHP is lower than that of the liquid flow channel. Gravity affects the thermal conductivity of the vapor and liquid flow channels, which in turn affects the performance of the FPMHP. Balancing the capillary force and porosity can improve the performance of the FPMHP under various operating angles.

Binary collision dynamics of equal-sized nanodroplets

Binary nanodroplet collisions have received increasing attention, whilst the identification of collision outcomes and the viscous dissipation mechanism have remained poorly understood. Using molecular dynamics simulations, this study investigates binary nanodroplet collisions over wide ranges of Weber number (We), Ohnesorge number (Oh) and off-centre distances. Coalescence, stretching separation and shattering are identified; however, bouncing, reflexive separation and rotational separation reported for millimetre-sized collisions are not observed, which is attributed to the enhanced viscous effect caused by the ‘natural’ high-viscosity characteristics of nanodroplets. Intriguingly, as an intermediate outcome, holes form in retracting films at relatively high We, arising from the vibration and thermal fluctuation of the films. Due to the combined effects of inertial, capillary and viscous forces, binary nanodroplet collisions fall into the cross-over regime, so estimating viscous dissipation becomes extremely important for distinguishing outcome boundaries. Based on the criterion that stretching separation is triggered only when the residual off-centre kinetic energy exceeds the surface energy required for separation, the boundary equation between coalescence and stretching separation is established. Here, viscous dissipation is calculated by the extracted flow feature from simulations, showing that the ratio of viscous dissipation to the initial kinetic energy depends only on Oh, not on We. Because of complex viscous dissipation mechanisms, the same boundary equation in the cross-over regime has also not been satisfactorily revealed for macroscale collisions. Therefore, the proposed equation is tested for wide data sources from both macroscale and nanoscale collisions, and satisfying agreement is achieved, demonstrating the universality of the equation.

Wicking-controlled interfacial water content for highly efficient solar desalination

Solar-driven interfacial evaporation offers a potential solution to address global freshwater scarcity. However, the water-thermal-vapor-salt imbalance issue severely affects the operating efficiency of the evaporator. This research examines the correlation among water supply height, spontaneous wicking rate, and interfacial water content. Subsequently, an engineering strategy is proposed to control the water concentration gradient within a two-dimensional solar absorber with vertical water supply channels. The results demonstrate that the hydrophilicity and internal structure of the material exert a crucial influence on the transport of bulk water. Specifically, longitudinal stripes within the water-conducting material promote a faster wicking rate and higher wicking height. This phenomenon occurs due to the combined effects of capillary forces and gravity, leading to a gradual decrease in liquid saturation along the capillary direction within the water-conducting material. By optimizing the water supply height and rate, the evaporation interface achieves a remarkable water evaporation rate of 1.50 kg m−2h−1. Building on this success, a novel configuration for a flow desalination evaporator is proposed, capable of sustaining the same evaporation rate even when operating continuously for 9 h in saltwater with a mass concentration of 20 %. Overall, this study emphasizes the importance of water and heat balance at the evaporative interface, reconciling conflicting requirements of interface flow and evaporation rate. These findings contribute to the development of highly efficient and reliable evaporators for sustainable freshwater generation.

Effects of Capillary and Viscous Forces on Two-Phase Fluid Displacement in the Microfluidic Model

Effects of Capillary and Viscous Forces on Two-Phase Fluid Displacement in the Microfluidic Model

Spontaneous Separation of Immiscible Organic Droplets on Asymmetric Wedge Channels with Hierarchical Microchannels.

Spontaneous separation of immiscible organic droplets has substantial research implications for environmental protection and resource regeneration. Compared to the widely explored separation of oil-water mixtures, there are fewer reports on separating mixed organic droplets on open surfaces due to the low surface tension differences. Efficient separation of mixed organic liquids by exploiting the rapid spontaneous transport of droplets on open surfaces remains a challenge. Here, through the fusion of inspiration from the fast droplet transport capability of Sarracenia trichome and the asymmetric wedge channel structure of shorebird beaks, this work proposes a spine with hierarchical microchannels and wedge channels (SHMW). Due to the synergistic effect of capillary force and asymmetric Laplace force, the SHMW can rapidly separate mixed organic droplets into two pure phases without requiring additional energy. In particular, the self-spreading of the oil solution on the open channel surface is utilized to amplify the surface energy difference between two droplets, and SHMW achieves the pickup of oil droplets floating on the surface of the organic solution. The maximum separation efficiency on 3-SHMW can reach 99.63%, and it can also realize the antigravity separation of mixed organic droplets with a surface tension difference as low as 0.87 mN·m-1. Furthermore, SHMW performs controllable separation, oil droplet pickup, and continuous separation and collection of mixed organic droplets. It is expected that this cooperative structure composed of hierarchical microchannels and wedge channels will be realized in resource recovery or chemical reactions in industrial production processes.

Numerical and Experimental Analysis of Dual-Beam Laser Polishing Additive Manufacturing Ti6Al4V.

Laser polishing is an emerging efficient technique to remove surface asperity without polluting the environment. However, the insufficient understanding of the mechanism of laser polishing has limited its practical application in industry. In this study, a dual-beam laser polishing experiment was carried out to reduce the roughness of a primary Ti6Al4V sample, and the polishing mechanism was well studied using simulation analysis. The results showed that the surface roughness of the sample was efficiently reduced from an initial 10.96 μm to 1.421 μm using dual-beam laser processing. The simulation analysis regarding the evolution of material surface morphology and the flow behavior of the molten pool during laser the polishing process revealed that the capillary force attributed to surface tension was the main driving force for flattening the large curvature surface of the molten pool at the initial stage, whereas the thermocapillary force influenced from temperature gradient played the key role of eliminating the secondary roughness at the edge of the molten pool during the continuous wave laser polishing process. However, the effect of thermocapillary force can be ignored during the second processing stage in dual-beam laser polishing. The simulation result is well in agreement with the experimental result, indicating the accuracy of the mechanism for the dual-beam laser polishing process. In summary, this work reveals the effect of capillary force and thermocapillary force on molten pool flows during the dual-beam laser polishing processes. Moreover, it is also proved that the dual-beam laser polishing process can further reduce the surface roughness of a sample and obtain a smoother surface.

The Seepage Mechanism of Micro Remaining Oil During Cyclic Waterflooding in Low-permeability Reservoir

To explore the flow mechanism of micro-remaining oil during cyclic waterflooding in low-permeability reservoir, the displacement effect of micro-remaining oil under conventional waterflooding and different rounds of cyclic waterflooding was investigated by using a micro-visual displacement experiment based on microfluidics model. The produced ratio of different types of micro remaining oil during cyclic waterflooding was quantified, and major types of micro remaining oils that can be applied effectively during cyclic waterflooding were analyzed. Moreover, the flow mechanism of micro remaining oil during cyclic waterflooding was investigated. Research results demonstrated that clustering type remaining oil and columnar type remaining oil were major types that were applied during cyclic waterflooding. After three rounds of cyclic waterflooding, clustering-type remaining oil decreased by 2.50% on average, and columnar-type remaining oil decreased by 0.81% on average. The major mechanism of cyclic waterflooding is introduced as follows: at intervals of cyclic waterflooding, clustering type remaining oil and columnar type remaining oil exchange with water in pores, throats, and spaces between big and small pores due to the fluctuation of pressure field and effect of capillary force. As a result, oil and water redistribute. Clustering-type remaining oil and columnar-type remaining oil become movable oils.

Experimental and computational investigation on synergistic enhancement spray cooling using micropillars and capillary-driven wicking hybrid structures

Spray cooling, which has a fast thermal response and low flow rate consumption, is a common and effective thermal management approach for high power electronic systems. Typically, to improve the heat transfer coefficient (HTC) for spray cooling, the target surface wettability is decreased, promoting nucleation boiling by reducing the surface energy barrier for bubble nucleation. However, the merging of bubbles and the formation of a vapor film have limitations in further increasing the critical heat flux (CHF). Hence, maximizing both the HTC and CHF of spray cooling can be mutually exclusive on the same heated surface. This paper presented a novel design for a vapor-liquid separation structure surface. It consisted of lower micropillars that serve as the vapor separation channel. On top of that, there was an upper multi-layer copper micromesh that wicks and spreads the coolant. Additionally, nano-grass attached to the micromesh to enhance capillary force and increase the nucleation sites simultaneously. Subsequently, we calculated the forward velocity and pressure drop of the droplets passing through the copper mesh to study the effects of droplet velocity and capillary force on heat transfer performance. The results show that the forward velocity of the droplets decreases rapidly as the increase of copper mesh layers and it drops to zero when passing through the third mesh. Therefore, the capillary force generated by the copper mesh is another important factor for the atomized droplets to pass through the copper mesh and reach the target surface. We have proven that all the vapor-liquid separation structure surfaces satisfy the condition ΔPcap>ΔPpore+ΔPlocal. Hence, the synergistic effects of the micropillar, copper micromesh, and nano-grass enable a circulation process of wicking-rewetting-vapor evacuation, which improves the onset of nucleate boiling (ONB), enhances the HTC, and increases the maximum heat flux dissipated by the system. Enhanced HTC (7.94 W/cm2/K) and maximum heat flux (817 W/cm2) were achieved at 1.50 ml/s on the vapor-liquid separation structure surfaces (#200 2-layer), representing an enhancement of 79.6% and 80.0% compared with that for the flat surface and the temperature of the heated surface at the ONB maximum decreased by approximately 30.8 °C.

Dynamic Fluid Connectivity Controls Solute Dispersion in Multiphase Porous Media Flow

AbstractSolute transport in multiphase flow through porous media plays a central role in many natural systems and geoengineering applications. The interplay between fluid flow and capillary forces leads to transient flow dynamics and phase distributions. However, it is not known how such dynamic flow affects the dispersion of transported species. Here, we use highly resolved numerical simulations of immiscible two‐phase flow to investigate dispersion in multiphase flows. We show that repeated activation and deactivation of different flow pathways under the effect of capillary forces accelerates the spreading of solutes compared to single phase flow. We establish the transport laws under dynamic multiphase flows by linking the dispersion coefficient to the Bond number, the ratio of the force driving the flow and the surface tension. Our results determine the controlling factors for solute dispersion in porous media, opening a range of applications for understanding and controlling transport in porous geological systems.

Special fog harvesting mode on bioinspired hydrophilic dual-thread spider silk fiber

Normal bioinspired spider silk fibers (BSSFs) show effective fog collection abilities but are weak in the rapid transport of captured droplets, which could potentially hinder the further improvement of fog harvesting efficiency. Factually, previous works have shown that the main axis of natural spider silk consists of two separate, parallel threads, similar to the microchannel structure of Sarracenia trichome. This structural feature may be an important factor contributing to the highly efficient fog harvesting ability of spider silks. However, to the best of our knowledge, previous studies on BSSFs have ignored this feature. In this work, inspired by spider silk and Sarracenia trichome, a novel bioinspired hydrophilic dual-thread spider silk fiber (HDSSF) is obtained via a simple dipping coating method to introduce capillary force. On the HDSSF, compared to previous works, a totally different fog harvesting mode was observed, i.e., captured droplets could be rapidly transported to spindle knots under the effect of capillary force and internal Laplace pressure difference via the connectivity of liquid film and no obvious droplets could be observed on the threads. The experimental observations and underlying mechanism analyses have verified that this special fog harvesting mode allows rapid transport and directional collection of droplets to accelerate the surface reconstruction rate, coupled with the high droplet capture ability of fiber, resulting in a significant improvement of fog harvesting efficiency (9.03 g cm−2·h−1, a 590% increase compared with normal BSSF). Such HDSSF is potentially applicable in high-efficiency fog harvesting systems, droplet transport devices and other engineering applications related to fog harvesting.

Damages of TZM as plasma facing material under transient heat load

Titanium-Zirconium-Molybdenum (TZM) is applied as the first wall material of EAST due to its excellent performance. To investigate the service behavior of TZM under transient heat fluxes, the postmortem inspection of in-situ damaged TZM tiles by plasma disruption heat load in EAST was analyzed. Meanwhile, the EMS-60 electron gun has been also used to test the transient heat load behaviors of TZM. There are some similar characteristics between the in-situ melting TZM and the ex-situ melting TZM tiles, but there are also some obvious differences. Specifically, in some melting zone, the surface morphology of partial in-situ TZM melting region is like that of ex-situ TZM melting areas, and their convex surface is relatively smooth, while the concave surface is relatively rough, and the solidification layer undergoes recrystallization. In other melting areas, there are many small pits on the surface of the TZM tile that was melted in-situ, but there are no obvious pits on the surface of the ex-situ TZM sample, and part of the surface of the TZM tile that was melted in-situ is like a big pit, and the melted TZM droplets in this melting area tend to splash towards the periphery. The capillary waves around the castle structure in the ex-situ test samples are the result of wetting effect of liquid metal and capillary force, and the holes in the resolidified layer is caused by the overheating boiling of TZM liquid. On the other hand, the number and propagation direction of cracks in the in-situ TZM tile are more complex than those in the ex-situ TZM sample. Firstly, the number of cracks on the in-situ TZM tile is large and dense, while the number of cracks on the surface of the ex-situ melting sample is small and scattered. The crack width of the in-situ tile is greater than that of the ex-situ tile. Secondly, the crack extension direction on the in-situ melted TZM is diverse, while the extension direction of the surface crack on the ex-situ TZM sample is relatively simple, and there is only one kind of crack on the tile surface. Such results provide reference for understanding the thermal behavior of TZM under transient heat flux in fusion devices.

Experimental investigation of heat transfer limitations in concentric annular sodium heat pipes and thermosyphon

This paper presents experimental investigations on the heat transfer performance of concentric annular heat pipe (CAHP) and thermosyphon (CATP) using sodium as a working fluid for microreactor applications. CAHP characterized by wicks on the inner and outer walls offers the potential to enhance capillary force and enable more compact microreactor designs. The research aims to understand the implications of structural differences between CAHP, CATP and conventional heat pipe (CHP) and identify favorable conditions for their use in microreactors. The thermal behavior and heat transfer limits of CAHP and CATP were examined under various boundary conditions. The experimental results revealed that CAHP exhibited capillary limits approximately 71.2% higher than cylindrical heat pipes under horizontal conditions. However, the Chi model used for predicting capillary limits showed a difference about 19.7% in horizontal operation and exceeded 44.6% in vertical operation, highlighting the need for considering the effect of non-uniform capillary forces in CAHP. The presence of additional inner wick in CAHP provided large evaporation areas, which facilitated rapid vapor generation and enabled the development of a continuum flow faster than in CHP, by approximately 70 °C. However, in vertical operation, CATP necessitates higher heat fluxes and exhibits notable temperature disparities between the evaporator and condenser regions compared to CAHP. This difference can be explained depend on the vapor generation mechanisms: heat pipes utilize additional wick area to facilitate evaporation, while thermosyphon depend on boiling that the advantages related to the annular flow path in CATP are not clear. Furthermore, the presence of an adiabatic section yields contrasting effects: while it promotes the formation of larger menisci in heat pipes, its presence is unfavorable in thermosyphons as it can elevate boiling temperatures that delayed operations. The findings underscore the advantages of CAHP over CHP, particularly in microreactor applications, provide insights into design optimizations for compact microreactors, and showed gaps in operating prediction models and experimental results.

Interconnected hollow fins to eliminate capillary blockage in vapor chamber condensers

The thermal performance of a vapor chamber can be greatly improved by using a heat sink radiator with hollow fins rather than plain fins. Since condensation takes place within the fins themselves, the temperature remains almost constant from their base to their tip, regardless of their length. This considerably increases the efficiency of the heat sink radiator and reduces the overall thermal resistance of the vapor chamber. There is, however, an important physical limitation to this solution: it is not possible to reduce the internal diameter of the fins below a critical value for which the capillary forces block the liquid within the fins. To overcome this limitation, a new condenser design with interconnected hollow fins is presented and tested in this paper. For comparative purposes, condensers with independent fins of similar diameter were also manufactured. Both types of condensers were tested with HFE-7100 and water as the working fluid to investigate the effect of capillary forces, which depend on both fluid properties and tube inner diameter. While systems with independent fins do not work with water because their fins are quickly flooded with condensate, no operating limit related to capillary forces was reached for the interconnected condensers. By pushing the operating limit further, interconnected fins pave the way for more compact and efficient thermal systems.

Pore-Scale Evaluation of Physicochemical Interactions by Engineered Water Injections

Engineered water injections have gained a lot of interest as an economic and effective method of improving the oil recovery. However, the complexity of the physicochemical interactions between the brines of various compositions, oil and rock has led researchers to provide multiple ways to explain this phenomenon. In this work, we evaluate the previously suggested mechanisms, namely wettability alteration and emulsification, against high-resolution micro-CT coreflood observations in a limestone sample. This is achieved by integrating the effects of above-mentioned mechanisms into a volume-of-fluid simulation by using geochemical modelling and experimental measurements. This has allowed us to explain the effect of capillary force affecting mechanisms, whereby we were able to achieve 6% increase in recovery factor. We have also observed that these mechanisms have limitation in improving recovery due to fingering and subsequent formation of the stagnation zones inside the core samples. When viscous effect is considered in numerical study, 22% increase in recovery is achieved by reorientation of the main flow paths and mobilisation of the previously unconnected oil clusters. This result is closer to 24% increase in recovery factor which was observed in experimental study and signifies that viscosity increase due to emulsification is an important mechanism of engineered water injections.