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1
Sedighi, Moghaddam Maziar. "Wettability of modified wood". Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175875.
Testo completoAbstract (sommario):
Despite many excellent properties of wood which make it suitable for many applications, it suffers from a number of disadvantages limiting its use. For instance, modification is needed to reduce water sorption and to improve decay resistance, dimensional stability and weathering performance. In addition, wood/liquid interaction such as water wettability on wood plays an important role in design and characteristics of many processes and phenomena such as adhesion, coating, waterproofing, wood chemical modification, and weathering. This thesis focuses on enhancing the understanding of wetting of wood, with emphasis on modified wood. The influence of surface chemical composition of wood and its microstructural characteristics on wetting and swelling properties has also been studied. A multicycle Wilhelmy plate technique has been developed to evaluate wetting properties of porous materials, such as wood, in which the samples were subjected to repeated immersions and withdrawals in a swelling liquid (water) and in a non-swelling liquid (octane). This method was utilized to dynamically investigate contact angle, sorption and swelling properties, as well as dimensional stability of unmodified, chemically and surface modified wood samples. Scots pine sapwood and heartwood samples were utilized to establish the principles of the technique. Acetylated and furfurylated wood samples with different level of modification were thereafter examined utilizing the developed technique for wetting measurements. A perimeter model based on a linear combination of the measured force and final change in sample perimeter was suggested to evaluate the dynamic dimensional stability of wood veneers. The feasibility of this method for studying dynamic wettability was investigated by measuring the changes of advancing and receding contact angles over repeated cycles on surface modified wood samples, created by combining liquid flame spray and plasma polymerisation methods. X-ray photoelectron spectroscopy (XPS) and X-ray computed tomography (XCT) were employed to study the surface chemical composition and microstructural properties of the samples, respectively. Three different kinetic regimes were observed in the wetting measurements: i) fast wetting and spreading of the liquid on the wood surface, ii) void filling and wicking and iii) swelling, which was the slowest of the three. The multicycle Wilhelmy plate method was found to be suitable for studying liquid penetration, sorption, and dimensional stability of swelling materials. The results demonstrate that the wetting properties of wood are highly affected by surface chemistry and microstructure. It was shown that using both swelling and non-swelling liquids in wetting measurements allow to distinguish between capillary liquid uptake and swelling. Based on this, for chemically modified samples, it was demonstrated that acetylation mostly reduces swelling, while furfurylation reduces both swelling and capillary uptake. This is in line with the microstructural study with X-ray computed tomography where a significant change in the porosity was found as a result of furfurylation, conversely acetylation left the total porosity values unchanged. Wetting results for hydrophobised wood samples demonstrate that the multi-scale roughness obtained by combination of nanoparticle coating and plasma polymerization increased both the hydrophobicity and the forced wetting durability compared to the micro-scale roughness found on wood modified with plasma polymerisation alone.QC 20151029
Sustainable wood modification
2
Melberg, Brita. "Nanostructured surfaces with patterned wettability". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19410.
Testo completoAbstract (sommario):
This project aims at the fabrication of a rough polydimethylsiloxane(PDMS) surface with patterned smooth areas. The idea is that such a surface will allow for water capturing on the smooth areas of the surface. The applications for this kind of surface are many, but especially the prospects of a surface able to trap droplets of cells in suspension by simply dipping the surface into the suspension is intriguing.From a previous project[1], and another student’s master’s thesis[2], the use of an etched copper surface seemed promising for the fabrication of a rough mold. This was abandoned after sandpaper turned out to be an even better mold, giving superhydrophobic PDMS(162, 33 ± 1, 40degrees).The negative photoresist SU-8 5 was used to pattern the sandpaper with small, circular features on the P1000 sandpaper(400μm and 1mm in diameter). The PDMS replica from this mold was a rough surface with smooth wells. This was not able to capture water droplets effectively, partly because air bubbles were trapped in the wells during the immersion in water. To avoid this, another mold was procured by the silanization of the previously made PDMS surface. The PDMS replica of the silanized PDMS had smooth pillars instead of wells, and did not succeed in trapping water droplets either. In fact, the smooth wells seemed to better at capturing the water.This project has succeeded in producing high enough roughness on PDMS to alter the contact angle with water by ∼ 61 degrees to a contact angle exceeding the lower limit for superhydrophobic surfaces by ∼ 12 degrees. The use of a sandpaper mold has proven to is simple, inexpensive and effective at producing PDMS with high contact angles.
3
Freiman, Gabriel, Jean-Pierre Korb, Benjamin Nicot e Patrice Ligneul. "Microscopic wettability of carbonate rocks". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192328.
Testo completoAbstract (sommario):
Nuclear Magnetic Relaxation Dispersion (NMRD) is strongly sensitive to the microscopic wettability of oil and brine bearing carbonate rocks. Exploring a very large range of low frequency enables isolating the typical NMRD dispersion features, 1/T1Surf, associated to
the different processes of molecular surface dynamics. This allows a separation of the surface and bulk microdynamics of oil and water even for a biphasic saturation of petroleum rocks. Several surface dynamical parameters were determined and related to the concept of microscopic wettability of oil and water in porous media.
4
Zhang, Xueyun. "Wettability tuning by surface modification /". View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CBME%202009%20ZHANG.
Testo completo
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Hobæk, Thor Christian. "Nanostructured PDMS surfaces with patterned wettability". Thesis, Norges Teknisk-Naturvitenskaplige Universitet, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-21045.
Testo completoAbstract (sommario):
In this study, a surface with patterned wettability by means of surface structuring, rather than through modifying the surface chemistry, was developed. The device presented in this thesis was inspired by the Namib Desert Bettle, which collects water from the fog by having hydrophilic spots surrounded by hydrophobic wax-coated regions on its back. Besides water collection, controlling the wetting behaviour locally on the surface may find applications within droplet-based microfluidics, or fabrication of DNA, protein or cell microarrays. Spatial wetting contrast was achieved through replica moulding of the elastomer polydimethylsiloxane (PDMS), using a copper and/or the epoxy-based SU-8 photoresist surface as a template. Different types of surface roughness was produced and characterized on polycrystalline copper, through etching, oxidation, electrodeposition, or a combination. Regions with no surface roughness was patterned on the template moulds through conventional UV-photolithography processing of SU-8. The PDMS replicas were then tested for the ability to capture water droplets selectively on the patterned spots. Through characterization of the surface roughness by atomic force microscopy (AFM) and scanning electron microscopy (SEM), copper plates etched with a solution of CuCl2 and HCl produced the highest amount of surface roughness, with longer etching times leading to increased surface roughness. To characterize the hydrophobicity, the contact angle was measured for droplets deposited on the rough PDMS surfaces. Through surface structuring, the contact angle was increased from 101.8 ± 3.6◦ for a flat surface, to 154.7 ± 5.3◦ for the PDMS surface with the highest roughness. The polarity of surface roughness was also found to play an important role in the wetting behaviour, with a higher number of peaks than valleys being preferable. The fabricated PDMS surfaces showed spatial wetting contrast, as demonstrated in the cover photo. The device needs further optimization in terms of increasing the hydrophobicity of the rough regions, as well as changing the pattern geometries. However, the discoveries made in this study may be useful for further development and integration with droplet-moving mechanisms, for future lab-on-a-chip applications within medical diagnostics or chemical analysis.
6
Alroudhan, Abdulkareem. "Wettability characterization using streaming potential measurements". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/52636.
Testo completoAbstract (sommario):
The surface charge of carbonate minerals, which is also expressed in terms of the zeta potential, plays a key control on reservoir wettability, and changes in the zeta potential have been invoked to explain wettability alteration and the release of previously trapped oil during controlled salinity waterflooding (CSW). We report a method to characterize the zeta potential of carbonates, based on measurements of streaming potential, which can be used to determine the zeta potential of mineral-brine and oil-brine interfaces within the porous medium. The aim of this project was to determine the effect of total salinity, potential determining ion (PDI) contribution, and wetting state on the zeta potential of limestone. In the first part, we use the streaming potential method to obtain measurements of zeta potential on intact core samples at typical reservoir brine salinity and composition. We determine the impact on zeta potential of varying the total salinity, and the concentration of the PDIs calcium, magnesium and sulfate. The impact of each PDI was determined over a wide range of concentrations naturally found in sea water, formation brines, and typical compositions used in CSW. We find that the zeta potential varies identically and linearly with calcium and magnesium concentration expressed as pCa or pMg. The zeta potential also varies linearly with pSO4. The sensitivity of the zeta potential to PDI concentration, and the IEP (iso-electric point) expressed as pCa or pMg, both decrease with increasing NaCl concentration. We report considerably lower values of IEP than most previous studies, and the first observed IEP expressed as pMg. The sensitivity of the zeta potential to PDI concentration is lower when measured using the SPM compared to the EPM, owing to the differing location of the shear plane at which the zeta potential is defined. In the second part, we use the streaming potential method to investigate how the zeta potential changes when an oil phase is introduced in the rock sample. We establish a relationship between wettability and the zeta potential. This is done for samples that were aged in the presence and absence of a brine phase, in order to represent mixed-wet and oil-wet cases. In addition, measurements on non-aged samples were conducted in order to represent the water-wet case. We find that the more oil-wet the system is, the more negative the zeta potential gets with the oil-wet case being the most negatively charged. For the crude oil samples, we find that there is a strong correlation between the Amott Index and the zeta potential. Our findings suggest that the streaming potential method can be used to assess the impact of water chemistry and wetting state on the surface charge of limestone. The results are directly applicable to wettability characterization and understanding of wettability alteration that may take place during CSW.
7
Chang, Jean H. "Tunable wettability of microstructured polypyrrole films". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62526.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85-90).
This thesis presents the development of the conducting polymer polypyrrole as a viable material for applications requiring switchable wettability. A fabrication procedure that produces robust microstructured polypyrrole (PPy) that quickly and reversibly switches between the superhydrophobic and superhydrophilic states is discussed. The polymer is doped with perfluorooctanesulfonate ions which diffuse in and out of the film upon an electric stimulus, causing a change in the material's surface energy. The effect of changing different deposition parameters on the switchable wettability of the polymer is also investigated. A post-deposition thermal treatment that improves the electrochemical properties of polypyrrole is presented. Finally, a device that allows for the in situ wettability switch of PPy is developed, eliminating the need for polypyrrole to be immersed in an electrolyte in order to switch between wetting states. A wettability gradient created on the surface of PPy using the device is used to demonstrate a possible application requiring induced fluid movement. Electrochemical techniques are used to synthesize and characterize the polymers, and scanning electron microscopy is used to examine the surface morphology of the films.
by Jean H. Chang.
S.M.
8
Fagehi, Raied Ahmed. "Interferometric assessment of contact lens wettability". Thesis, Glasgow Caledonian University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.688303.
Testo completo
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Facanha, Juliana Maria de Fonseca. "Fundamentals of wettability applied to Brazilian Pre-Salt reservoirs and wettability alteration evaluation in low salinity water injection". Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3319.
Testo completoAbstract (sommario):
Brazilian Pre-Salt carbonate reservoirs have been one of the greatest oil discoveries of the past decade. In fields such as Lula, it is expected to recover between five to eight billion barrels of oil equivalent. To fulfill this, knowledge of reservoir wettability is fundamental, given that it dictates how fluids (water, oil and, gas) are distributed within the porous media, and how the multiphase flow occurs in the pore-network. This information is important in the construction of relative permeability curves which are input for reservoir simulators. Few works have been published regarding initial wettability of Pre-Salt carbonate reservoirs in spite of their great oil recovery potential. In this way, to close the data gap in the literature, this study aimed to investigate parameters that influence initial wettability of pure rocks (calcite and quartz) and analogue rocks (coquinas) that partly represent the Pre-Salt reservoirs. Contact angle experiments were used to study the influence of parameters that are important to rock wettability, such as rock composition, brine salinity, temperature, rock ageing and, presence of carbon dioxide in brine. Initial wettability was analysed at core scale by spontaneous imbibition and core flood experiments, obtaining the Amott index to water. Through these experiments, it was possible to evaluate the performance of di erent brines respective to oil recovery. Furthermore, wettability alteration was investigated in low salinity water injection as a tertiary injection method. Contact angles experiments were also used to analyse wettability alteration in clay-less rocks, focusing on understanding the role of fluid-fluid interactions on low salinity water injection. Respective to initial wettability in pure rocks and rock analogues relevant to the Brazilian Pre-Salt, it was found that at reservoir temperature (60°C) calcite, and quartz were neutral and weakly oil-wet, respectively. Amott index to water indicated that at that temperature, coquina rocks were intermediate-wet (mixed-wet). Presence of carbon dioxide in brine indicated that both calcite and quartz rocks become more water-wet. Regarding the application of wettability to low salinity water injection, the results suggested that wettability alteration is not exclusive of clayey rocks, nor resulting from a change in the ratio of divalent to monovalent cations. They indicated that crude oil composition is crucial for wettability alteration to happen, and it is possible that crude-oil/brine interactions dictate the low salinity effect. In summary, this work generated important data regarding initial wettability of Brazilian Pre-Salt reservoirs which are scarce in the literature. These results also instigate further investigation respective to the effects of carbon dioxide in brine on the initial wettability of rocks considering complex brines (presence of divalent cations and anions) rather than just brines composed of sodium chloride. This work showed that crude-oil/brine interactions is important for the low salinity effect.
10
Badge, Ila. "Tuning Wettability And Adhesion Of Structured Surfaces". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1393716842.
Testo completo
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VILLA, Fabio. "Effect of Wettability on Phase Change Phenomena". Doctoral thesis, Università degli studi di Bergamo, 2017. http://hdl.handle.net/10446/89510.
Testo completo
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Falah, Toosi Salma. "Superhydrophobic polymeric surfaces : fabrication, wettability, and antibbacterial activity". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62353.
Testo completoAbstract (sommario):
This PhD thesis studies fabrication of superhydrophobic polymeric surfaces, their wetting properties, and their antibacterial activities as potential application to medical sciences. A femtosecond laser technique was used to fabricate mico/nano- structures on the surface of PTFE and PU. The effect of laser parameters (fluence, scanning speed, and overlap) on the wettability of the resulted micro/nano-patterns was studied. Two techniques were used to laser-scan the surface, namely uniaxial and biaxial scan. Uniaxial scan creates channeled morphology with direction-dependent wettability. To produce uniform wettability independent of direction, biaxial scanning was examined, which creates well-defined pillars with very high contact angle (CA) and very low contact angle hysteresis (CAH).
To facilitate and speed up the surface micro/nano-structuring, laser-ablation was coupled with thermal imprinting. The metallic femtosecond laser-ablated templates were employed to imprint micron/submicron periodic structures onto the surface of several polymers. The CA of imprinted polymers increased to above 160°, while their CAH varied significantly depending on the surface thermophysical and chemical properties.
A unique technique was developed to create superomniphobic patterns on HDPE through hot embossing. The filefish skin dual scale superoleophobic patterns were used as a biological model to develop angled microfiber arrays on HDPE. The obtained bioinspired surface is highly capable of repelling both water and liquids with low surface tensions that meets the superomniphobic criteria.
The effect of superhydrophobicity on protein adsorption and bacterial adhesion of laser-ablated PTFE substrates were investigated. Samples were incubated in Gram negative (E.coli) and Gram positive (S.aureus) bacteria cultures, BSA solution, IgG solution, and blood plasma for 4 hours. All superhydrophobic surfaces were found to be more resistant to protein /bacteria adhesion compared to the corresponding smooth samples. However, some of the most superhydrophobic PTFE surfaces were found to exhibit the highest adherence with protein/bacteria; while some other did not allow any adsorption/adherence of protein/bacteria respectively towards the end of the incubation. Besides the CA, CAH, average height of pillars, and spacing distance between
iii
the pillars, this study showed that there are other roughness factors, which play crucial role in the durability of the superhydrophobic surfaces such as the distribution of pillar heights.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
13
Kwok, Queenie Sau Man. "Investigation of the wettability of ammonium nitrate prills". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ61031.pdf.
Testo completo
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Xuan, Changji. "Wettability and Agglomeration Characteristics of Non-Metallic Inclusions". Doctoral thesis, KTH, Tillämpad processmetallurgi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183069.
Testo completoAbstract (sommario):
In this thesis, both the wettability and the agglomeration characteristics of non-metallic inclusions in liquid iron/steel were studied by using both experimental results and thermodynamic considerations. The mechanisms of the wettability of different types of inclusions were discussed. Also, the agglomeration behaviors of the inclusions were analyzed. Firstly, the wettability of different types of inclusions (including Al2O3, MgO, Ti2O3, TiO2 and TiN) in contact with the liquid iron/steel was studied. For the TiNcase, there is no reaction formation at the interface between TiN and pureiron/steel. In the caseo f pure Fe, the oxygen increase is the main factor for a contact angle decrease. As for the steel case, a sharp decrease of the contact angle is due to the effects of both an increased oxygen content in the liquid steel and a formation of a Ti(N,C,O) phase at the interface. For the Al2O3 and MgO cases, the formation of a FeAl2O4 and a MgO-FeO reaction layer at the interface, respectively, lead to a contact angle decrease. In the case of the Ti2O3/pure Fe case, the reaction at the interface cannot be identified. For the Ti2O3/steel case, the formation of an Al2TiO5 reaction layer is the main reason for a steep decrease of the contact angle. In the TiO2 case, the melting region appears at the temperature below the melting point of pure iron. This is due to the strong formation of a solid solution TiOx-FeO. The main source of the oxygen for the solid solution formationis due to a TiO2 substrate decomposition and a low partial pressure of oxygen in the chamber. Regarding to the non-metallic particle additions (TiO2 and TiN) into the molten steel, the steel composition should be controlled to have a small Al content (<0.005mass%) and a high Ti content (>0.035mass%), so as togeta high number of Ti-rich oxide inclusions with a small size. This conclusionis supported from the view point of the van der Waals force, liquid-capillary force and wettability. Regarding the Ti/Al complex deoxidation in the melt, the “mainly occupied clustered inclusions” with spherical shape is due to a TiOx-FeO liquid inclusion precipitation after an addition of Ti as a pre-deoxidizer. The much lower cluster number in the Ti/Al case than that in the Al case is mainly due to a coagulation of single TiOx-FeO liquid inclusions. Also, the cluster formation in a complex Ti/Al deoxidation is started after an Al addition rather than after a Ti addition. Regarding the Al2O3 cluster formation in deoxidation, the cavity bridge forceis larger than the van der Waals force. However, the difference between them is smaller than 7 times. In the reoxidation process, the influence of the cavity bridge force due to the wettability decreased, and became similar to that of the liquid-capillary force.QC 20160301
15
Martinez, Nelson. "Wettability of Silicon, Silicon Dioxide, and Organosilicate Glass". Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc12161/.
Testo completoAbstract (sommario):
Wetting of a substance has been widely investigated since it has many applications to many different fields. Wetting principles can be applied to better select cleans for front end of line (FEOL) and back end of line (BEOL) cleaning processes. These principles can also be used to help determine processes that best repel water from a semiconductor device. It is known that the value of the dielectric constant in an insulator increases when water is absorbed. These contact angle experiments will determine which processes can eliminate water absorption. Wetting is measured by the contact angle between a solid and a liquid. It is known that roughness plays a crucial role on the wetting of a substance. Different surface groups also affect the wetting of a surface. In this work, it was investigated how wetting was affected by different solid surfaces with different chemistries and different roughness. Four different materials were used: silicon; thermally grown silicon dioxide on silicon; chemically vapor deposited (CVD) silicon dioxide on silicon made from tetraethyl orthosilicate (TEOS); and organosilicate glass (OSG) on silicon. The contact angle of each of the samples was measured using a goniometer. The roughness of the samples was measured by atomic force microscopy (AFM). The chemistry of each of the samples were characterized by using X-ray photoelectron spectroscopy (XPS) and grazing angle total attenuated total reflection Fourier transform infrared spectroscopy (FTIR/GATR). Also, the contact angle was measured at the micro scale by using an environmental scanning electron microscope (ESEM).
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Pulipaka, Sriharsha. "The Effect of Surface Wettability on Heterogeneous Condensation". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204852063.
Testo completo
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Annavarapu, Rama Kishore. "Elastocapillary Behavior and Wettability Control in Nanoporous Microstructures". University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544705326035201.
Testo completo
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Martinez, Nelson Yohan Reidy Richard F. "Wettability of silicon, silicon dioxide, and organosilicate glass". [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/ark:/67531/metadc12161.
Testo completo
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Li, Xuekai (Jimmy). "Estimation of Formation Rock Wettability from Acoustics Measurement". Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/86470.
Testo completoAbstract (sommario):
In this thesis, acoustics measurement is used to estimate the wettability of the formation rock. The wettability effect on the wave propagation in the saturated porous media is studied by applying the slip boundary condition (SBC), which plays an important role in the wave-induced-fluid-flow (WIFF). The wettability dependent wave velocity and attenuation are studied theoretically and experimentally. A practical method is developed to estimate the wettability of the formation rock by the acoustics measurement.
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MALAVASI, Ileana. "Wettability effects on interface dynamics and phase-change". Doctoral thesis, Università degli studi di Bergamo, 2016. http://hdl.handle.net/10446/52325.
Testo completo
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MALAVASI, Ileana. "Wettability effects on interface dynamics and phase-change". Doctoral thesis, Università degli studi di Bergamo, 2016. http://hdl.handle.net/10446/222101.
Testo completoAbstract (sommario):
The present thesis is a result of three year research study aimed at understanding the wettability effects on interface dynamics and phasechange. The project was performed in between University of Bergamo, University of Mons, CNR-ISTEC Institute of Science and Technology for Ceramics (Faenza, Italy), Politecnico di Milano and Italian Space Agency (ASI).
The scope was to add a piece of the puzzle in understanding the basic physics knowledge on the wettability influence on: 1) pool boiling heat transfer; 2) liquid-surface interaction.
Energy saving and research for the development of alternative energy sources are the major concerns of the twenty-first century. The solution is twofold:
- dependence on traditional energy sources should be eliminated and it serves to found renewable energy sources;
- serves to determine innovative methods to increase the efficiency of the current energy systems in order to save conventional energy resources, increasing their sustainability.
Researches shown that the miniaturization in the production of electromechanical systems is a key factor in the development of energy-efficient systems. The requests, for example, of electronic devices, such as smartphones, tablet and laptop, more and more small and thin, but with increasingly high performance, lead to a denser associated electronics packaging, in which the heat generated per unit area is increased. Heat that must be removed and that is dissipated through the use of innovative heat exchange devices, such as microfluidic devices. The increase of the performance of these devices involves focusing on the heat exchange phenomena that occur inside these systems, and in particular on the boiling process, that is the evaporation at the solid-liquid interface when the surface temperature is higher than the temperature of the fluid in saturation condition. Research also show that the heat exchange performance of a surface is in function of its roughness and wettability. For this reason, pool boiling experiments were carried out with degassed water on stainless steel substrates with different surface topography and wettability. Boiling curves have been measured together with visual high-speed observations of the boiling process. The onset temperature of nucleate boiling has been measured and the influence of surface roughness and wettability has been quantified for different surfaces, with the aim to better understand the effect of superhydrophobicity on pool boiling. The original finding is that the boiling curve shape is rather different between hydrophilic and superhydrophobic case, keeping the same surface roughness: superhydrophobic surfaces show a peculiar behaviour similar to an early “quasi-Leidenfrost” regime for low superheat, i.e. once boiling is initiated, the boiling process immediately enters the film boiling regime. Also, for the roughness range analysed, the wettability has a predominant effect with respect to the roughness, when the contact angle exceeds the typical value for superhydrophobic surfaces (receding contact angle θrec > 135°). The theme of the energy saving also concerns the impact of drops on dry solid surfaces, since the process is involved in many industrial processes, i.e. spray cooling, ink-jet printing, spray painting, fuel injection, raindrop erosion. The investigation and the comprehension of the dynamics of a single drop impact is the first step to understand and control the liquid-solid interaction of more complex phenomena, such as the formation of fouling in the marine environment, the formation of ice on aircraft wings, the pressure drops in the ducts and the oxidation in the pipe-line. For this reason, a considerable part of the work has been then devoted to study experimentally, using a highspeed camera, the normal impact of water and hexadecane liquid drops onto dry, rigid surfaces with different wettabilities. The results highlighted that it is not possible to easily correlate contact angles (receding, advancing and hysteresis) and drop impact outputs on different surfaces. In order to explain the observed phenomena, physical and chemical characteristics of both the liquid drops and the surfaces have to be taken into account. Surface morphology is crucial in defining the critical velocity over which impalement occurs. Also surface chemistry is relevant, as dipolar interactions between surface functional groups and molecules in the liquid phase can favour impalement. As far as the liquid properties are concerned, with increasing viscosity and lower fluid surface tension the Cassie-to-Wenzel transition, i.e. impalement of the liquid meniscus into the texture, shifts to smaller Weber. These results emphasize how an accurate design of the surface properties must be pursued in the future research towards dynamically amphiphobic surfaces.
Moreover, the construction of an experimental apparatus for the evaluation of the heat exchange coefficients of an oscillating interface is reported. This part of the work is included in the appendix as such apparatus has been designed and built, however no experiments were performed.
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Man, Hing Nung. "Pore scale modelling of petrophysical characteristics of hydrocarbon reservoir rocks". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271230.
Testo completo
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Qi, Yusen. "Heterogeneous nucleation and influence of surface structure and wettability". [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0008384.
Testo completo
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Bryne, Lars-Elof. "Aspects on wettability and surface composition of modified wood". Licentiate thesis, KTH, Civil and Architectural Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4735.
Testo completoAbstract (sommario):
Wood is often combined with other materials such as thermoplastics, adhesives and coatings. In general, combinations of wood and polymers especially in outdoor exposure have poor long-term durability. This behaviour can be related to an insufficient wood-polymer adhesion due to the low intrinsic compatibility between the wood substance and the polymers used. Another source for woodpolymer de-bonding is the high hygroscopicity of wood and great difference in hygro-thermal properties between the components.
The basic conceptual idea related to this work is to reduce the hygrosensitivity of wood by applying different wood modification methods, in particular, acetylation, furfurylation and heat treatment. The effects of such chemical modifications of wood, also accompanied with ageing effects, on its adhesion properties with commonly used synthetic polymers are, however, not well understood. In this context, the over-all purpose of this thesis is to achieve a better understanding of wood-polymer adhesion and interfacial forces which also may guide us to tailor the interaction between modified wood and e.g. thermoplastics and adhesives. The main focus of this thesis is therefore to apply contact angle analysis based on the Chang-Qin-Chen (CQC) Lewis acid-base model in order to estimate the work of adhesion (Wa) between the wood, modified wood and certain polymers. Contact angle measurements on wood samples were performed based on the Wilhelm plate principle. Related to this, an effort was also made to characterize the studied modified wood surfaces according to morphology and chemical composition. The methods that have been used are low vacuum scanning electron microscopy (LV-SEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS).
Results show that so-called interaction parameters can be successfully estimated for prediction of Wa between wood and polymers using the applied CQC model. Furthermore, such wetting analysis was successfully related to spectroscopic findings of the chemical composition of the wood samples surface. Ageing effects, i.e. the time after preparation of the wood surface, play a central role for the surface characteristics. In most cases, ageing resulted in a significant decrease of Wa between wood and water and a moderate decrease between wood and thermoplastics. The surface characteristics of acetylated wood were, however, more stable over time compared to unmodified, furfurylated and heat treated wood. The predicted Wa with the adhesives for heat treated and acetylated wood was increased due to ageing. Future work is planned to involve studies in order to relate such predicted adhesion properties with the actual performance of various wood-polymer systems.
25
Tangen, Mathias. "Wettability Variations within the North Sea Oil Field Frøy". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18416.
Testo completoAbstract (sommario):
Wettability is one of the most important parameters governing the rate of oil recovery from a porous medium. This thesis is a study of the wettability variations within the Frøy field in the North Sea, and its effect on the oil recovery. Several reports regarding the wettability and relative permeability of the Frøy field are available, and the conclusions from these reports are presented. The overall conclusion is that Frøy is on the oil-wet side of the wettability scale, with measured Amott-Harvey wettability indices ranging from -0.00189 to -0.73. An attempt was made to find wettability trends, relating the wettability index to variables such as distance above the water-oil contact, geological facies, permeability, the core’s staining level and so on, based on the measured data. Unfortunately, no such trend was identified.Only nine wettability measurements were available from the Frøy field while writing this thesis. This thesis concludes that in order to get a good statistical data set that can be used for establishing wettability trends, several wettability tests should be performed on cores sampled from a variety of distances above the water-oil contact, with different permeabilities and color staining levels, representing different rock types. And it is important to make sure that the cores have their original (native) wettability during the tests.More than 50 simulation cases have been made and run during the work on this thesis, testing the effect of wettability variations on Frøy, using the Schlumberger reservoir simulation program Eclipse 100. Wettability variations are simulated by assigning different relative permeability curves to different saturation function regions in the reservoir. For this reason, five sets of relative permeability curves were made, that represents wettabilities ranging from slightly water-wet to oil-wet, and different combinations of these curves were used in the simulation cases. There are many uncertainties in the given data and there are different ways of initializing the simulation model which may affect the simulation results. These issues are discussed in a separate chapter of the thesis.The simulation results showed that when the reservoir rock went from water-wet to oil-wet, the oil production went down, the water production went up, the water breakthrough occurred earlier and the oil recovery factor went down. The different producing wells were not equally affected by changes in the wettability.Two important conclusions were drawn from the simulation results. Firstly, it is difficult to estimate the effect of wettability variations on the production profiles if not the aquifer support and the fault transmissibility factors are modeled correctly, since these parameters also affect the production. And secondly, it is the wettability of the bottom half of the 225 meter thick reservoir zone that affects the production profiles of the wells. The wettability of the top half of the reservoir zone hardly affects the production profiles at all.
26
Plaisance, Marc Charles. "Cellular Response to Surface Wettability Gradient on Microtextured Surfaces". Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/53730.
Testo completoAbstract (sommario):
Objective: Topography, chemistry, and energy of titanium (Ti) implants alter cell response through variations in protein adsorption, integrin expression, and downstream cell signaling. However, the contribution of surface energy on cell response is difficult to isolate because altered hydrophilicity can result from changes in surface chemistry or microstructure. Our aim was to examine a unique system of wettability gradients created on microstructured Ti on osteoblast maturation and phenotype.
Method: A surface energy gradient was created on sand-blasted/acid-etched (SLA) Ti surfaces. Surfaces were treated with oxygen plasma for 2 minutes, and then allowed to age for 1, 12, 80, or 116 hours to generate a wettability gradient. Surfaces were characterized by contact angle and SEM. MG63 cells were cultured on SLA or experimental SLA surfaces to confluence on TCPS. Osteoblast differentiation (IBSP, RUNX2, ALP, OCN, OPG) and integrin subunits (ITG2, ITGA5, ITGAV, ITGB1) measured by real-time PCR (n=6 surfaces per variable analyzed by ANOVA/Bonferroni’s modified
Student’s t-test).
Result: After plasma treatment, SLA surface topography was retained. A gradient of wettability was obtained, with contact angles of 32.0° (SLA116), 23.3° (SLA80), 12.5° (SLA12), 7.9° (SLA1). All surfaces were significantly more hydrophilic than the original SLA surface (126.8°). Integrin expression was affected by wettability. ITGA2 was higher on wettable surfaces than on SLA, but was highest on SLA1. ITGAV and ITGB1 were decreased on hydrophilic surfaces, but ITGA5 was not affected. IBSP, RUNX2, and ALP increased and OPG decreased with increasing wettability. OCN decreased with increasing wettability, but levels on the most wettable surface were similar to SLA.
Conclusion: Here we elucidated the role of surface energy on cell response using surfaces with the same topography and chemistry. The results show that osteoblastic maturation was regulated in a wettability-dependent manner and suggest that the effects are mediated by integrins.
27
Buckley, Jill S. "Mechanisms and consequences of wettability alteration by crude oils". Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/1298.
Testo completoAbstract (sommario):
Reservoir wettability is controlled by crude oil/brine/rock interactions that have not been well understood. Studies using either model compounds or crude oil fractions have had only limited success in reproducing the wetting alteration that can occur in nature. In this study, the approach is first to identify the key features of interfacial activity unique to crude oils, then to design and conduct wetting alteration experiments—using both flat solids and porous media—that demonstrate the mechanisms by which alteration can occur. Components of crude oils that are interfacially active are found in the highest molecular weight, most polar fractions of the oil, the resins and asphaltenes. How these components affect wetting depends on the compositions of not only the oil, but also the mineral surfaces and the aqueous phase that is always present in oil reservoirs. Wettability altering interactions can occur by several mechanisms. In the absence of water, adsorption of polar species can create intermediately-wet surfaces. If the oil is a poor solvent for its asphaltene fraction, adsorption of large asphaltene aggregates can make surfaces fairly oil-wet. Adsorption can also occur because of ionic interactions between oppositely charged acidic and basic sites at the oil/water and solid/water interfaces. There may also be interactions between similarly charged sites, if ion binding can occur. All of these mechanisms have been documented for a range of crude oils with varying asphaltene fraction, solvency, acid number, and base number.
28
Garza, Tanya Cruz. "Optimizing wettability of externally wetted microfabricated silicon electrospray thrusters". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38648.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 67-70).
Electrospray propulsion devices with externally wetted architectures have shown favorable performance. The design of microfabricated silicon thrusters and their feed systems requires an understanding of propellant flow over a silicon surface. This research explores the parameters that affect wettability of externally wetted microfabricated silicon electrospray thruster arrays and how varied wetting surface treatments affect thruster performance. Silicon samples with various black silicon treatments were fabricated and optimal black silicon etch parameters were determined by measuring the samples wettability. Silicon wettability was analyzed by producing samples with various black silicon treatments and then measuring contact angle, measuring surface roughness, imaging surface geometry, calculating spreading rates, and performing treated thruster current output tests. Two propellants, 1-ethyl-3-methyl-imidazolium tetraflouroborate (EMI-BF4) and 1-ethyl-3-methyl-imidazolium bis(triflouromethyl-sulfonyl)amide (EMI-IM), were used in contact angle measurements and spreading rate experiments. A model describing the spread of a small drop of EMI-BF4 and EMI-IM over roughened silicon substrates is presented.
(cont.) Models which describe the spread of small, non-reactive drops over perfectly smooth substrates predicts a 1/5th power dependence of spreading area with time. Experimental spreading data of EMI-BF4 loosely supported this theory showing an average of 1/3rd power dependence of spread area with time. A model of propellant spreading is proposed here suggesting that viscous spreading reaches an equilibrium with constant radius and provides a capillary pressure source for porous flow through the black silicon surface for the remainder of the spreading. This theory is compared with experimental data of EMI-BF.K and EMI-IM propellant spread over roughened silicon. Future work in propellant supply to a thruster surface is discussed. Theoretical and experimental areas of study are proposed to understand physical flow mechanisms involved in electrospray thrusters.
by Tanya Cruz Garza.
S.M.
29
Wang, Xin C. "Surface wettability studies of PDMS using flame plasma treatment". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54483.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 30).
The flame plasma treatment studied in this thesis was able to oxidize the surface of Polydimethylsiloxane (PDMS) in a fraction of a second. It was found to be a much faster way to modify PDMS surface wettability than the current technologies. The surface wettability of Polydimethylsiloxane (PDMS) treated with flame plasma was studied. The surface wettability was characterized by contact angle measurements using water and a surface tension liquid as the probe liquids. Two experimental parameters were varied in this investigation: a) distance from the PDMS surface to the inner flame cone; b) the dwell time of the PDMS under the flame. The study concluded that the same surface wettability can be achieved through different combinations of distance and dwell time. The shortest dwell time needed to induce a contact angle of 100 or less on the treated PDMS surface in this experimental setup was approximately 0.18 second. This study also found that over treatment of the PDMS surface in the flame plasma yielded a reversal treatment effect and decreased the surface wettability. The flame plasma yielded uniform contact angle measurements within 15% across the PDMS surface. The recovery mechanism in the treated PDMS surfaces was dominated by the diffusion of untreated polymers from the bulk PDMS to the treated surface. The results from this investigation demonstrated the potential for the flame plasma treatment to be used in rapid manufacturing of PDMS microfludic devices.
by Xin C. Wang.
S.B.
30
Albarakati, Nahla. "Aging Effect in the Wettability of Nickel Nanorod Arrays". VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/227.
Testo completoAbstract (sommario):
The time-dependent wettability of nickel nanorod arrays was studied by measuring their water contact angles as a function of "aging" time in air. The nickel nanorod arrays were deposited on silicon substrates by DC magnetron sputtering using an oblique angle of 85° with respect to the substrate normal. By changing the deposition time from 10 to 90 min., the diameter, height, and separation of the nanorods were varied. The water contact angles of each sample were then periodically measured from a minimum aging time of 30 min. after deposition and exposure to air, up to a maximum aging time of three months. The initial water contact angles for all samples were approximately equal to 8o, indicating that the nickel nanorod arrays were initially superhydrophilic. As the samples aged in air, however, they all showed increasing contact angles as a function of time that were nonlinear with different rates. The results can be grouped into two categories: thinner samples with shorter deposition times (10 to 55 min) demonstrated faster rates of increase in contact angle, and thicker samples with longer deposition times (60 and 90 min.) showed slower rates. The increase in contact angle with time indicates that the Ni nanorods become more hydrophobic with aging time in air. Surface chemical analysis demonstrates that this increase in hydrophobicity may be due to oxidization and hydrocarbon contamination, which depend on the nanorod morphology. X-ray photoelectron spectroscopy results indicate that thinner samples (10-55 min. deposition time) have more adsorbed carbon as compared to thicker samples (60 and 90 min.). It appears that the reactivity of the Ni nanorods with air ambient is enhanced for shorter, smaller-diameter nanorods.
31
Bou-Zeid, Wassim. "Wettability and evaporation of sessile drops of biological fluids". Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4348/document.
Testo completoAbstract (sommario):
Le processus d'étalement et d'évaporation d'une goutte de suspensions de particules sur une surface solide est très intéressant permettant la formation de motifs. Une étude expérimentale à été effectuée avec du sang total humain et avec des fluides purs dans une chambre sous atmosphère contrôlée en humidité relative. Pour des angles de contact faible, le processus d'étalement/évaporation peut être divisé en deux régimes. Un premier régime rapide gouverné par un équilibre entre les forces visqueuses et les forces capillaires et un deuxième régime plus lent dominé par la cinétique d'évaporation. Nous montrons que les bio-colloïdes jouent un rôle significatif sur la dynamique de la ligne de contact. La vitesse moyenne de la ligne de contact suit la même dynamique d'étalement que le modèle de Tanner, où le temps d'étalement et les paramètres géométriques de la goutte sont fonctions de l'humidité. Dans cette étude, nous montrons que l'humidité relative influence les paramètres géométriques de la goutte et par conséquent le motif a la fin du processus d'évaporation. Un modèle purement diffusif pur a été obtenu dont le diamètre de mouillage et l'angle de contact sont fonction de l'humidité. Pour l'analyse morphologique des motifs de craquelures, une méthode de segmentation manuelle a été utilisée comme une méthode de référence pour la validation de la méthode de segmentation automatique développée dans "iBlood". Par cette méthode, nous montrons que la cinétique d'évaporation influence la distribution structurelle et morphologique des cellules de forme trapézoïdale, et par conséquent, l'espacement des fractures moyenne finaleSpreading/evaporation process of droplets over solid surfaces is a fundamental process and a wide research field because of number of applications in printing, micro-electronics, DNA analysis and even in biomedical. This experimental work aims to investigate the effect of relative humidity on the contact line dynamics, on the evaporation dynamics and on the final pattern of a drop of whole human blood. The spreading of a pure fluid model that has the same physical properties as human blood was studied and compared to the blood. We showed that bio-colloids play significant effect on the dynamics of contact line and the pinning effect of the drop. For low contact angles, we showed that the spreading/evaporation process could be divided into two regimes. A fast first regime determined by a balance between viscous forces and capillary forces and a second slower regime dominated by the evaporation rate. Physical mechanisms that are responsible for the spreading enhancement are proposed and discussed. The average velocity of the contact line was found to follow the same behaviour as Tanner's model, where the spreading dynamics and geometrical parameters of the droplet are function of relative humidity. The experimental measurements are in a good agreement with the purely diffusive model where the equilibrium wetting radius and contact angle are function of relative humidity. For the morphological analysis of crack patterns, a manual segmentation method was used as a reference for the validation of the automatic developed segmentation method. We showed that the evaporation rate influences structural distribution of plaques in the corona region and hence, the mean crack spacing
32
Kallel, Wissem. "Pore-scale modelling of wettability alteration in microporous carbonates". Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3305.
Testo completoAbstract (sommario):
While carbonate reservoirs are recognized to be weakly- to moderately oil-wet at the core-scale, wettability distributions at the pore-scale remain poorly understood. In particular, the wetting state of micropores (pores < 5 μm in radius) is crucial for assessing multi-phase flow processes, as microporosity can determine overall pore-space connectivity. Nonetheless, micropores are usually assumed to be water-wet and their role in multi-phase flow has often been neglected. However, oil-wet conditions in micropores are plausible, since oil has been detected within micropores in carbonate rocks. Modelling the wettability of carbonates using pore network models is challenging, because of our inability to attribute appropriate chemical characteristics to the pore surfaces in the presence of the oil phase and over-simplification of the pore shapes. First, we carry out an investigation of the prevalent wettability alteration scenario due to heavy polar compounds (e.g. asphaltenes) adsorption from the oil phase onto the surface, which occurs strictly after oil invasion. We develop a physically-plausible wettability distribution that we incorporate in a quasi-static two-phase flow network model which involves a diversity of pore shapes. The model qualitatively reproduces patterns of wettability alteration recently observed in microporous carbonates via high-resolution imaging. To assess the combined importance of pore-space structure and wettability on petrophysical properties, we consider a homogeneous Berea sandstone network and a heterogeneous microporous carbonate network, whose disconnected coarse-scale pores are connected through a sub-network of fine-scale pores. Results demonstrate that wettability effects are significantly more profound in the carbonate network, as the wettability state of the micropores controls the oil recovery. Second, we develop a novel mechanistic wettability alteration scenario that evolves during primary drainage, involving small polar non-hydrocarbon compounds present in the oil (e.g. alkylphenols, carbazoles, etc.). We implement a diffusion and adsorption model for these compounds that triggers a mild wettability alteration from initially water-wet to more intermediate-wet conditions. This mechanism is incorporated in the quasi-static pore-network model to which we add a notional time-dependency of the invasion percolation mechanism. The model qualitatively reproduces experimental observations where an early rapid wettability alteration occurred during primary drainage. Additionally, we are able to predict clear differences in the primary drainage patterns by varying both the strength of wettability alteration and the balance between the processes of oil invasion and wetting change, which control the initial water saturation for waterflooding. In fact, under certain conditions, the model results in higher oil saturations at predefined capillary pressures compared to the conventional primary drainage. In particular, it leads to the invasion of micropores even at moderate capillary pressures in the microporous carbonate network. Additionally, the model results in significant changes in the residual oil saturations after waterflooding, especially when the wetting state is altered from intermediate-wet to more oil-wet conditions during ageing.
33
Yaseri, Ahmed Zarzor Hussien. "CO2 wettability of rock and implications for core-flooding". Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/68275.
Testo completoAbstract (sommario):
Rock became more CO2 wet with increasing pressure, temperature and brine salinities and less CO2 wet with increasing surface roughness - i.e. a lower storage capacity can be inferred for structural trapping. Moreover, we demonstrate that gas densities correlate remarkably well with wettability also a physical model was developed to provide a theoretical framework. Furthermore, the permeability of sandstone samples reduced after injection of brine, CO2-saturated brine or supercritical CO2 at reservoir conditions.
34
Abbasi, Ghazanfer R. "Investigating the wettability effect on gas hydrate bearing sediments". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2023. https://ro.ecu.edu.au/theses/2650.
Testo completoAbstract (sommario):
Natural gas trapped in hydrate deposits is a potentially enormous source of energy which can in principle be extracted from the underground reservoir structures. These reserves can potentially also catastrophically release very large quantities of greenhouse gases to the atmosphere. Natural Gas Hydrate (NGH) occurs in sediments under certain pressure and temperature conditions and has the potential to meet the increasing global energy demand. However, an efficient exploitation of NGH requires a precise characterization and understanding of the hydrate formation, accumulation and dissociation mechanisms. In this work, a comprehensive study has been conducted to augment the understanding of NGH and their wettability behaviour in hydrate bearing sediments. Systematic experiments were conducted to address this by developing various approaches presented in this work. The approaches adopted to achieve the study objectives were: i) review of previous research on NGH, ii) the effect of wettability on gas hydrate in sediment, iii) the influence of rock wettability on the electrical resistivity of hydrate bearing sediments (HBS), (iv) wettability effect on measured velocity properties of HBS.
In this context, the micro-structural characterization of gas hydrate is essential and requires the use of specialized methods and equipment. While traditional imaging and characterization tools offer fundamental microstructure analysis, X-ray micro-computed tomography (μCT) has gained recent attention to produce high resolution three dimensional (3D) images of pore structure and pore habits of hydrate-bearing sediments and provide spatial distribution and morphology of gas hydrate. Micro-CT (μCT) offers direct visualization of hydrate structure and growth habits at high resolution ranging from macro-metric to micro-metric scale, therefore, it is extensively used in natural gas hydrate characterization. This review, therefore, summarizes the theoretical basis of μCT imaging spanning the setup of the experimental apparatus and visualization techniques. The applications of μCT in natural gas hydrate reservoirs characterization – hydrate types and constituent, physical and chemical properties of gas hydrates as well as their occurrence and accumulation are presented. Hydrate characterization using μCT imaging including the general understanding of hydrate pore habit prediction, hydrate saturation and percolation behaviour, hydrate seepage and permeability and the influence of hydrate saturation on the mechanical properties of hydrate-bearing sediments (HBSs) are explicitly discussed. Lastly, conclusions and recommendations for future research are provided. Thus, this review offers a reference for understanding in the application of micro-CT to evaluate gas hydrates – which in turn contributes towards the exploitation of these energy resources.
One key parameter which is well known to strongly influence fluid distribution, saturation and production is rock wettability. However, the effect of wettability on gas hydrate in sediment has not been investigated yet. We thus used nuclear magnetic resonance (NMR) spectrometry to measure relaxation times (T₂ and T₁) and the corresponding surface relaxivity of tetrahydrofuran (THF) hydrate during formation and dissociation in water- and oil-wet Bentheimer sandstone. We also measured the NMR porosities and hydrate saturations at different temperatures during hydrate formation/dissociation for both water-wet and oil-wet sandstone. Significantly higher hydrate saturation was observed in water-wet sandstone (when compared to oil-wet sandstone) at all stages of hydrate formation and dissociation. Furthermore, the T₂ spectra moved from the lower relaxation domain (before hydrate formation) to the fast relaxation domain (after hydrate formation) in both, water-wet and oil-wet sandstone. However, water-wet sandstone generally had a T₂ relaxation range due to the higher water affinity to water-wet rock and the associated faster demagnetization of the water molecules. These results demonstrate that low-field NMR can be used to quantify the rock wettability and observe hydrate behaviour in geologic sediments. This fundamental information thus aids in the development of gas extraction from hydrate reservoirs, and the assessment of potential greenhouse gas emissions from such reservoirs into the atmosphere.
Classically, rock wettability is one of the key factors in predicting fluid flow behavior, fluid distribution, reserves and productivities. However, the effect of wettability on electric resistivity of hydrate formations is only poorly understood. Thus, to evaluate the influence of rock wettability on the electrical resistivity (note that resistivity logging is a key well logging tool) of hydrate-bearing sandstone, Nuclear Magnetic Resonance experiments were conducted. Clearly, the effective porosity and liquid saturation increased with increasing temperature, due to hydrate dissociation. Furthermore, resistivity index, rock resistivity (Rt), and formation factor all decreased with increasing liquid saturation, and the formation factor demonstrated a positive correlation with hydrate saturation, though formation factor for oil-wet (OW) sandstone was higher than that of the water-wet (WW) sandstone. This work will thus significantly improve the fundamental understanding of the petrophysical properties of gas hydrate reservoirs, so that energy production can be optimized, geo-hazards can be avoided, and the hydrate gun hypothesis can be better assessed.
Furthermore, the effect of wettability on velocity properties of hydrate formations is poorly understood. Thus, to evaluate the key information about wettability effect on measured velocity properties of hydrate bearing sandstone, we conducted several experiments followed by NMR measurements. The P-wave velocities of water wet, and oil wet sandstones were obtained before and after hydrate formation. Our results demonstrate that the percentage of velocity in water wet sample is higher than oil wet sample which indicates high hydrate saturation in water wet sandstone. This is also confirmed by the NMR results which also showed that the hydrate saturation in water wet sandstone is higher than that in oil wet sandstone. This study can be used to quantify the hydrate occurrence in different wetting conditions. This study provides insights on acoustic velocity measurements for hydrate formation in the gas production pipelines.
35
Singh, Manjinder. "Modelling of miniature heat pipes based on wettability gradient". Thesis, IIT, Delhi, 2019. http://eprint.iitd.ac.in:80//handle/2074/8078.
Testo completo
36
Ballard, Tracey Jane. "An experimental study of some mechanisms of formation damage caused by oil-based drilling fluid filtrate". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47762.
Testo completo
37
Rogers, Ronan. "In vitro and ex vivo wettability of hydrogel contact lenses". Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2974.
Testo completoAbstract (sommario):
The wettability of contact lenses has become an area of intense research, with the belief that the more "hydrophilic" or wettable the lens surface is, the more comfortable the lens may be, as the posterior surface of the eyelid will move more smoothly over it, hence increasing comfort. There are many ways to assess the wettability of a given material, namely sessile drop,1 captive bubble 2 or Wilhelmy plate. 3 This thesis used the sessile drop method to determine the surface wettability of various hydrogel contact lens materials, by measuring the advancing contact angle made between the lens surface and a pre-determined volume of HPLC-grade water. This was followed by measuring the surface wettability following periods in which the lens materials were soaked in various contact lens care regimens. Further studies determined wettability of lens materials after various periods of in-eye wear and finally a study was undertaken to evaluate if a novel biological technique could be used to differentiate proteins that deposit on hydrogel lens materials that may affect wettability and cause discomfort.
A variety of hydrogel lenses, taken directly from their packaging and after soaking in various care regimens, were analyzed to determine their sessile drop advancing contact angles, in vitro. These studies indicated that poly-2-hydroxyethylmethacrylate (pHEMA)-based lenses are inherently more wettable than silicone-based lenses, unless they have a surface treatment that completely covers the hydrophobic siloxane groups. Additionally, certain combinations of lens materials and care regimens produce inherently more wettable surfaces when measured in vitro.
Suitable methods to assess contact lens wettability ex vivo, or after subjects had worn lenses for set periods of time, were developed. It was determined that using latex gloves to remove lenses had no impact upon the lens surface wettability and that rinsing of the lens surface after removal from the eye was required to determine the wettability of the underlying polymer.
The final wettability studies involved an analysis of various lens materials from clinical studies conducted within the Centre for Contact Lens Research (CCLR). These studies investigated differences in wettability between silicone hydrogel lenses manufactured from differing polymers and variations in ex vivo wettability of several combinations of lens materials and solutions, worn for varying periods of time.
A novel method to investigate proteins extracted from lenses using 2D-Difference in Gel Electrophoresis (DIGE) found that this technique could be used to analyze proteins extracted from contact lenses. The data obtained showed that there was no difference between a group of subjects who were symptomatic of lens-induced dryness or a control group, and that care solutions had a minimal influence on the pattern of deposition seen.
The overall conclusion of these studies is that hydrogel lens wettability is affected by the polymer composition and that care regimen components can modify the surface wettability.
38
Haddad, Mera. "In vitro and in vivo investigation of contact lens wettability". Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518475.
Testo completo
39
Grishaev, Viktor. "Impact of particle-laden drops on substrates with various wettability". Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209072.
Testo completoAbstract (sommario):
Since decades, drop impact has been a popular topic of investigation for the importance that such a phenomenology has in many different application domains.So far, the effect of micro-particles on the drop impact morphology has been studied for a limited number of configurations and often modelled as a change in the viscosity of the carrier fluid. However, this approach has been found sometimes questionable. The aim of the thesis is to better understand the phenomenology associated with particle-laden drop impact such as the distribution of particles in splats and to extend the number of experimental configurations for particle-laden drop impact to occur.
The impact of millimetre-size particle-laden drops was investigated for hydrophilic and hydrophobic substrates. The drops were dispersions of water and round, spherical and nearly iso-dense hydrophobic particles with diameters around 200 µm and 500 µm. The substrates were transparent glass and polycarbonate plates. The impact was studied by side, bottom and angle view images in the range 148≤We≤744 and 7092≤Re≤16368.
The particles were found to suppress the appearance of singular jetting and drop partial rebound, and also cause early splashing, receding break-up and rupture. The occurrences of these phenomena depend on the impact velocity, particles’ diameter and volume fraction. The drops with 200 µm particles spread in two phases: fast and slow, caused by inertial and capillary forces, respectively. Also, the increase of volume fraction of 200 µm particle leads to a linear decrease of the maximum spreading factor caused by the inertia force on the hydrophilic and hydrophobic substrates. The comparison of our data and the existing ones for splashing led to the formulation of а new splashing criterion for particle-laden drops. The novel criterion improves upon current models in predicting the splashing threshold by introducing effect of particle volume fraction and particle wettability. The analysis of particle distribution showed that 200 µm particles formed atypical distributions in splats after the impact in contrast to 500 µm particles with random pattern. The 200 µm particles formed rings/disks and a crown-like structure on hydrophilic and hydrophobic substrates, respectively. These patterns were described by correlations.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
40
Shirafkan, Abbas. "Wettability and hydrophilicity of rigid and soft contact lens surfaces". Thesis, City University London, 1997. http://openaccess.city.ac.uk/8385/.
Testo completoAbstract (sommario):
In the last two decades an abundance of contact lens materials with unknown surface properties have been introduced as well as new contact lens design. Recent studies have identified the importance of physical and chemical interactions between materials and liquids. The purpose of this experimental research work was to investigate the relationship between a contact lens surface and a liquid. The wettability and hydrophilicity of both soft and rigid contact lens surfaces were determined using two novel techniques and an established method. The two novel techniques were the un-separated adherent quid/laser method and the adherent liquid/ maximum force method whereas the established technique involved monitoring the receding wetting angle and interface are a diameter of a sessile drop. Contact lens surface preparation and the method of removing a liquid from hydrated surfaces were found to be important variables when determining wettability or hydrophilicity. Experiments showed that the use of surface tension to remove liquid from hydrated surfaces significantly improved the reproducibility of subsequent measurements. Variation of the sessile drop wetting angle and interface area diameter with evaporation time demonstrated different values for different contact lenses. The clinical consequence of monitoring the receding values would be; if a material to spread tear break up time occurs the dry patches will be advanced on PMMA, rather than Paraperm contact lens. Surface hydrophilicity, if defined in terms of the maximum adherent force, describes the ability of a lens surface to attract a liquid, whereas wettability may be defined as the ability of a liquid to spread on a contact lens surface. The wettability and hydrophilicity, therefore, are two different issues. When a wetting angle is 01, or close to 0" the surface is described as wettable. Results demonstrated that Equalens had a greater surface wettability and hydrophilicity than the PMMA for pre-wear, but the post-wear hydrophilicity for PMMA was greater than Equalens. The use of each measurement method, therefore, resulted in a value that is intrinsically related to measurement method and definition. The clinical consequenceo f the valuesi s to help practitioners prescribea lens material either on wettability or hydrophilicity values. In contact lens practice, a lens surface is required to maintain a stable tear film and produce a long tear film break up time. A combination of hydrophilicty and wetting angle values can help to determine the requirement of wettability and hydrophilicity in the contact lens industry and also in practice. It can be concluded that no single test can fully describe the surface properties of contact lens surface materials, but it is proposed that information and results from a series of tests provides the most useful clinical description.
41
Kershaw, Matthew James. "Wettability and fluid absorption studies utilising environmental scanning electron microscopy". Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423651.
Testo completo
42
Al-Shehri, Hamza Saeed A. "Wettability of anisotropic and porous particles adsorbed to fluid interfaces". Thesis, University of Hull, 2015. http://hydra.hull.ac.uk/resources/hull:15376.
Testo completoAbstract (sommario):
The wettability of particles and the way they attach to liquid interfaces is important for many technologies where powders are mixed with liquids or used as emulsifiers. Most such powders are highly agglomerated into larger aggregates that are highly porous. The attachment of such porous particles to liquid–fluid interfaces has not been studied in detail, especially in cases where the porous particles are impregnated with another fluid phase. The overall aim of the thesis is to study the behaviour of particles at the liquid–fluid interface with an emphasis on non– spherical and porous solid particles. We study the orientation of anisotropic microparticles and measure the contact angle of smooth and porous microparticles with the gel–trapping technique (GTT) to find the wettability of microparticles adsorbed in fluid interfaces. This technique allows us to obtain micrographs by scanning electron microscopy (SEM) for particles resting on polydimethylsiloxane (PDMS), which replicates the non–polar phase and allows for measuring the particle contact angle. We show the results of the typical attachment and orientation of needle–like (aragonite), rhombohedra–like (calcite) microcrystals and ethyl cellulose micro–rods, as well as highly porous hydrophilic and hydrophobic silica microparticles at these liquid interfaces. The importance of these results is in gaining an understanding of the adsorption behaviour and demonstrating actual information on anisotropic particles which have potential applications in industrial formulations and products. We also investigate how carboxylate modified latex (CML) microparticles adsorb at liquid surfaces and the preferred type of emulsion they can stabilise depending on the particle size and the surface density of carboxylic groups. We also study, both theoretically and experimentally, the effect of salt in the aqueous phase on the contact angle of such microparticles. The main finding is that the wettability of CML microparticles is governed by the carboxylic group density on the particle surface rather than their ionisation. We demonstrate that the type of Pickering emulsions is governed by the wettability of microparticles at the oil–water interface. We study the effect of the initial impregnation of porous particles with polar or non–polar phases on their attachment at liquid interfaces both theoretically and experimentally. Model supra–particles have been prepared by using building blocks of smaller colloid particles packed in a spherical aggregate. The particles were produced by drying latex particle suspensions of various particle volume fractions and concentrations, followed by partial fusion of the particles achieved by thermal annealing. We have studied the particle surface morphology and porosity and showed how the annealing temperature, the initial particle volume fraction of sulphate latex suspension and the evaporation temperature can be used to control the supra–particle final structure and porosity. Furthermore, we have investigated the link between the wettability of the porous supra–particle building blocks, i.e. sulphate latex particles, and the macroscopic (apparent) contact angle of the porous supra–particle when attached to liquid surfaces. The contact angles of porous supra–particles infused with water at the oil–water interface were found to be much bigger than those at the air–water interface as expected. We also show how the type of liquid filling the pores of the supra–particle affects its macroscopic contact angle at the oil–water interface.
43
BHAT, KAILASH. "ELECTROWETTING TEXTILES - A NEW PARADIGM FOR TUNING OF TEXTILE WETTABILITY". University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1186679134.
Testo completo
44
He, Lvmeng. "Surface Treatments to Tailor the Wettability of Carbon Nanotube Arrays". Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1441896877.
Testo completo
45
Ho, YeeHsien. "Laser Surface Modification on Az31b Mg Alloy for Bio-wettability". Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc407788/.
Testo completoAbstract (sommario):
Laser surface modification of AZ31B Magnesium alloy changes surface composition and roughness to provide improved surface bio-wettability. Laser processing resulted in phase transformation and grain refinement due to rapid quenching effect. Furthermore, instantaneous heating and vaporization resulted in removal of material, leading the textured surface generation. A study was conducted on a continuum-wave diode-pumped ytterbium laser to create multiple tracks for determining the resulting bio-wettability. Five different laser input powers were processed on Mg alloy, and then examined by XRD, SEM, optical profilometer, and contact angle measurement. A finite element based heat transfer model was developed using COMSOL multi-physics package to predict the temperature evolution during laser processing. The thermal histories predicted by the model are used to evaluate the cooling rates and solidification rate and the associated changes in the microstructure. The surface energy of laser surface modification samples can be calculated by measuring the contact angle with 3 different standard liquid (D.I water, Formamide, and 1-Bromonaphthalen). The bio-wettability of the laser surface modification samples can be conducted by simulated body fluid contact angle measurement. The results of SEM, 3D morphology, XRD, and contact angle measurement show that the grain size and roughness play role for wetting behavior of laser processing Mg samples. Surface with low roughness and large grain size performs as hydrophilicity. On the contrast, surface with high roughness and small grain size performs as hydrophobicity.
46
Alyafei, Nayef. "Capillary trapping and oil recovery in altered-wettability carbonate rock". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/29415.
Testo completoAbstract (sommario):
Understanding the displacement and trapping of a displaced phase in porous media is important for applications in improved oil recovery (IOR) and carbon capture and storage (CCS). In IOR, we design the process to leave as little residual oil behind as possible, while for CCS, we do the opposite: we wish to maximise the amount of CO2 trapped by the host brine. Reservoir rocks display a range of wettability, from being preferentially water-wet they spontaneously imbibe water to oil-wet, or water repellent. Many rocks are mixed-wet, with both water-wet and oil-wet pores. The other wettability state is more intermediate-wet where, as we show, the rock appears to be largely non-wetting to both oil and water. Carbonate reservoirs, which house the majority of the world's remaining conventional oil, and which offer potential storage locations for carbon dioxide, have an altered wettability after contact with crude oil. In this thesis we study spontaneous displacement and trapping in carbonate rocks for different wettability conditions. The rate of spontaneous imbibition governs the rate with which oil, or carbon dioxide is trapped, while the residual saturation quantifies how much trapped. This is particularly important in carbonate reservoirs, which are almost extensively fractured. In these reservoirs, the principal mechanism for displacement is spontaneous imbibition of water to displace oil (or carbon dioxide) in the water-wet portions of the pore space. Pore structure and wettability are two of the main factors affecting displacement and capillary trapping. Experimental and pore-scale modelling studies have found a monotonic increase of residual non-wetting phase saturation, Snwr, with the initial non-wetting phase saturation, Snwi in a water-wet medium. However, altered-wettability systems have received relatively little attention, particularly those which are intermediate-wet. We first present the three carbonates we study in this thesis: Estaillades, Ketton and Portland. These are three quarry limestones that have very different pore structures and span a wide range of permeability. We present standard core analysis results including mercury injection capillary pressure and nuclear magnetic resonance response. We also study three-dimensional X-ray images of these samples, obtained at a resolution of a few microns. We use these experiments to assess the pore size distribution; we show that all the samples have micro-porosity and use the results to interpret the trapping and displacement experiments performed later. We then perform spontaneous imbibition experiments in these three carbonates under strongly water-wet conditions. We use scaling equations and recently published analytical solutions to assess the recovery of these rocks. We perform two sets of experiments. In the first, we measure the mass of water imbibed as a function of time. We show that the amount imbibed scales as the square root of time. In the second series of experiments, we measure saturation profiles as a function of distance and time using X-ray CT scanning. We demonstrate that the saturation profiles are functions of distance divided by the square root of time. We also demonstrate that the profiles are consistent with the analytical theory and, using reasonable estimates of relative permeability and capillary pressure, we can match the experimental results with the analytical solutions. We discuss how, in combination with conventional measurements of relative permeability (steady-state or using Buckley-Leverett theory in an unsteady-state experiment) these measurements could be used to measure capillary pressure and relative permeability. In the next phase of the study, we use organic acid (cyclohexanepentanoic acid) to alter the wettability of our samples and observe the relationship between the initial oil saturation and the residual saturation. We take cores containing oil and a specified initial water saturation and waterflood until 10 pore volumes have been injected. We record the remaining oil saturation as a function of the amount of water injected. In the water-wet case, with no wettability alteration, we observe, as expected, a monotonic increase between the initial and the remaining oil saturation. However, when the wettability is altered, we observe an increase, then a decrease, and finally an increase in the trapping curve for Estaillades limestone with a small, but continued, decrease in the remaining saturation as more water is injected. This behaviour is indicative of mixed-wet or intermediate-wet conditions as there is no spontaneous imbibition of oil and water. However, Ketton did not show indications of a significant wettability alteration with a similar observed trapping profile to that observed in the water-wet case. Portland limestone also showed a monotonic increasing trend in residual saturation with initial saturation but with a higher recovery, less trapping, than the water-wet case. Again, this is intermediate-wet behaviour with no spontaneous imbibition of either oil or water, and slow production of oil after water breakthrough. Finally, we repeat the same experiments but instead we age the three carbonates with a high asphaltenic content and high viscosity crude oil at 70C mimicking reservoir conditions. The results show a monotonic increase in residual saturation as a function of initial saturation but with higher recovery than the water-wet cases for Estaillades and Portland, with again no indication of wettability alteration for Ketton. We discuss the results in terms of pore-scale recovery process and contact angle hysteresis. We observe recovery behaviour that lies between the water-wet and mixed-wet conditions previously studied in the literature. Overall, the thesis demonstrates that recovery rate and the amount of trapping are sensitive to pore structure and wettability. Very different recovery trends were observed for three rocks with similar chemical composition. The work serves as a benchmark for further modelling and experimental studies. The recommendation is to reproduce, in the laboratory, conditions close to those observed in the reservoir, and to use imbibition and displacement measurements to quantify and constrain multiphase flow properties.
47
SAINT, AIME Ricot. "An Evaluation of NAPL Wettability in 2-D Visualization Experiments". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/764.
Testo completoAbstract (sommario):
The presence of light non-aqueous phase liquid (LNAPL) in the subsurface constitutes a long-term source of pollution for groundwater. Hence understand the movement of NAPL in the subsurface is essential in order to design effective remediation technology. Their movement in the subsurface is so complex that researchers have been using different media, different NAPLs, and conducted experiments in 1-D column, 2-D tank and 3-D tank in order to study the phenomenon. To solve the problem of limitation in flow boundaries in 1-D researchers have used two dimensional (2-D) tanks made of glass and plexiglass. However there have been some questions concerning the possible impact of NAPL wettability on materials use to construct the tank. This wettability may influence the flow of fluids at the visual interface. A representative LNAPL (dodecane) was released in the vadose zone of an Ottawa sand. Two external constant head reservoirs were used to maintain a constant water table in the tank. Time-series digital images of plume were used to analyze the geometry and position of the plume in the tanks regarding to the water table. Then relative geometry of the LNAPL was compared to Pantazidou and Sitar's equation. In both the sand and the glass tank, water is the wetting fluid, whereas dodecane (LNAPL) is the non-wetting fluid. However, on the plexiglass the LNAPL is the wetting fluid. As a result 40% and 70% difference were observed between glass and plexiglass tanks regarding the length and the thickness, and the area was twice the size of the plume in the glass tank. This demonstrates that the tank material is an important parameter to be considered on flow visualization of NAPL. Moreover, the influence of ethanol on dodecane was tested on a 2-D tank in glass. The results showed that the presence of ethanol appears to influence on the size and position of the plume in the subsurface.
48
Chen, Yongqiang. "Geochemical Modelling to Characterize Wettability of Oil-Brine-Rock Systems". Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/78325.
Testo completoAbstract (sommario):
Low salinity waterflooding appears to be a cost-effective and environmentally friendly means to improve oil recovery by increasing hydrophilicity. However, the controlling factor(s) behind this process remains unclear. This research characterized wettability of oil-brine-rock system from nano to pore scale through a combination of experiments and geochemical modelling, providing insights to better model multiphase flow at subsurface. New findings can also help to constrain the intrinsic uncertainties of CO2-assisted EOR with respect to wettability alteration.
49
Al-Khdheeawi, Emad Abdulhusain Fakher. "Influence of Rock Wettability on Reservoir-Scale CO2 Geo-Sequestration". Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/79906.
Testo completoAbstract (sommario):
The focus of this research is to investigate the influence of rock wettability on CO2 movement through porous media. By performing different multiphase flow reservoir simulations on a hectometre scale, this research investigates the effects of wettability, wettability spatial distribution, and factors affecting wettability on the efficiency of CO2 trapping mechanisms. The results of this research show that reservoir wettability significantly influences CO2 storage efficiency and that water-wet reservoirs are preferable CO2 sinks.
50
Wong, William Sai Yau. "Exploitation of Super(de)wettability via Scalable Hierarchical Surface Texturing". Phd thesis, Canberra, ACT : The Australian National University, 2017. http://hdl.handle.net/1885/146424.
Testo completoAbstract (sommario):
The field of wettability is an age-old topic that has been
revitalized in the last two decades. Historically, the diverse
physical phenomena of wetting has influenced the development of
inventions that dates back to the paleolithic era (2,600,000 to
10,000 BC) in the form of charcoal and ochre -based cave
paintings, or the mesolithic (10,000 to 5,000 BC) and neolithic
(5,000 to 2,000 BC) periods as pottery and soaps. Since the end
of the Stone Age, human civilizations and scientific discoveries
have progressed by leaps and bounds. Despite the advances in
metallurgy, optics, chemistry, mechanics, mathematics and
electricity, our understanding of fluid-surface interactions
remained stagnant until 1804. Between 1804 and 1805, Thomas Young
described the concept of a wetting contact angle, which controls
the equilibrium shape of a fluid droplet on a surface, thus
making wettability a quantified branch of physics. The late entry
of this scientific field is astounding, considering the
ubiquitousness of water on Earth. Despite Young’s discoveries,
the area remained largely unexplored. Work on wettability was
intermittent, with Edward Washburn on capillary effects in 1921
and later on, Robert Wenzel and Cassie-Baxter in 1936 and 1944 on
the wetting of rough interfaces.
In 1997, almost exactly 20 years ago, the field was rejuvenated
by the corresponding discoveries of superhydrophilicity (water
droplets spread into a sheet) and superhydrophobicity (water
droplets ball up), by Wang et al. and Neinhuis et al.
respectively. Since their work into these distinct
super(de)wetting states, the field has grown exponentially.
Today, its revival can be attributed to biomimetics (engineering
mimicry / imitation of life) and a revolutionized understanding
behind super(de)wetting mechanisms that are found in nature. The
precise combination of hierarchical (multi-scale) texturing with
select surface chemical composition is vital towards fabricating
interfaces with specialized wetting properties. Knowledge behind
the careful control of surface texturing holds immense potential
for enabling a plethora of user-defined functional interfaces. As
of the time of writing, the field of wettability encompasses
multiple domains, such as superhydrophilicity (water-loving),[8]
slippery superhydrophobicity (water-fearing), adhesive
superhydrophobicity (an unintuitive love-fear relationship with
water), superoleophobicity (oil-fearing), superamphiphobicity
(water- and oil-fearing),[11] superomniphobicity (all-fearing) as
well as a range of other important intermediary,
cross-environment wetting states.
Methods employed for achieving super(de)wettability can be
broadly classified under 2 sub-classes. The first relies on
intricate top-down photolithography (-drawing with light) or
templating-based designs while the other uses the realms of
chaotic, but deterministic and scalable bottom-up self-assembly.
Both routes are promising for the development of unique
super(de)wetting states, albeit with considerable drawbacks on
both fronts. For instance, while lithography and templating have
demonstrated exemplary surface texturing precision and
super(de)wetting performance, these methods remain limited by
poor scalability, complexity and costs in instrumentation and
operation. Alternatively, scalable and cheap bottom-up
self-assembly methods can exist within complex electro-, hydro-,
aero-, thermal- or thermo-dynamically varied regimes.
Consequently, each system requires intense cross-optimization
research efforts in determining niche operating parameters.
In this work, we explore a series of highly promising
hierarchically structured material interfaces that were enabled
by understanding, taming and controlling scalable but chaotic
bottom-up methods. To this end, we demonstrate their potential
within the entire super(de)wetting spectrum, showcased through a
series of coatings and further exemplified by functional
micro(fluid)mechanical systems (M-F-MS).