No description available.

No description available.

No description available.

As environmental awareness raises the expectations to reduce emission of modern diesel engines are growing as well. Fuel diversity and the advanced injector systems requires even more attention on an ever existing problem which is called nozzle hole fouling. Recent literature and observations at Scania indicate the phenomena is connected to fuel filter plugging caused by metal carboxyl contaminants through the formation of “soft particles”. This report begins with a literature review about the nature of agglomerates in biodiesel. Followed by the evaluation of six particle sizing equipment. This include one ensemble technique based on Brownian motion, namely dynamic light scattering. The remaining five techniques are single particle counters, including a high speed camera system, light blocking system, Nano tracking analysis and two different approaches using light microscope. To characterise the structure and chemical components of the particles SEM, EDX, FT-IR and ICP-OES were used. From the above mentioned methods optical microscopy was chosen to be the best method to evaluate the particle distribution. The main reasons for this is the ability to measure particles in the solution in the desired size range and the possibility to couple it with a Raman spectrometer, providing possibilities for future studies. Besides finding the best technique to measure the particles, a secondary result is the negation of Zinc-neodecanoate creating particles in the fuel. It opposes the assumption made in the literature about filter blocking, and it finds the need for deeper understanding of the nature of soft particles.

When a biomaterial is inserted into the body, the interaction of the surface with the surrounding biological environment is crucial. Given the importance of the surface, the ability to alter the surface properties to support a compatible environment is therefore desirable. Silicone hydrogel contact lenses (CL) allow for improved oxygen permeability through the incorporation of siloxane functional groups. These groups however are extremely surface active and upon rotation, can impart hydrophobicity to the lens surface, decreasing lens wettability and increasing protein and lipid deposition. Lens biofouling may be problematic and therefore surface modification of these materials to increase compatibility is exceedingly recognized for importance in both industry and research. The current work focuses on the creation of a novel anti-fouling polymer surface by the incorporation of 2-methacryoyloxyethyl phosphorylcholine (MPC), well known for its biomimetic and anti-fouling properties. A controlled polymerization method was used to generate a unique double-grafted architecture to explore the effect of increasing surface density of polyMPC chains on corresponding anti-fouling properties. The novel free polymer was synthesized by a 3-step atom transfer radical polymerization (ATRP). First, poly(2-hydroxyethyl methacrylate) (polyHEMA) was polymerized by ATRP, where the hydroxyl (OH) groups of the polymer then underwent an esterification to create macroinitiating sites. From these sites, a second ATRP of poly(MPC) varying in length occurred, yielding the double-grafted polymer poly(2(2-bromoisobutyryloxy-ethyl methacrylate)-graft-poly(2-methacryloyloxyethyl phosphorylcholine (pBIBEM-g-pMPC). The polymer was designed for resistance to protein adsorption through a possible synergistic effect between the surface induced hydration layer by surrounding PC groups coupled with steric repulsion of the densely grafted chains. To test its potential as a surface modifier, the polymer was grafted from model silicone hydrogel CL through a 4-step surface initiated ATRP (SI-ATRP) in a similar manner to the free polymer. First, the ATRP initiator was immobilized from the HEMA OH groups of the unmodified CL, generating Intermedate-1. A polyHEMA brush was grafted from the initiating sites yielding pHEMA-50, followed by the generation of a second initiator layer (Intermediate- 2). A sequential ATRP of poly(MPC) then generated the target pMPC-50/pMPC-100 surfaces. For the free pBIBEM-g-pMPC polymer analysis, 1H-NMR and GPC determined polymers formed with a predictable MW and low polydispersity (PDI). For surface grafting, using a sacrificial initiator, 1H-NMR and GPC indicated that the pHEMA-50 and pMPC-50/pMPC-100 polymers were well-controlled, with a MW close to the theoretical and a low PDI. For surface chemical composition, ATR-FTIR showed the presence of the ATRP initiator (Intermediate-1 and 2) by the appearance of a C-Br peak and disappearance of the OH peak. XPS confirmed the chemical composition of the 4-step synthesis by a change in the fraction of expected surface elements. Both the surface wettability and EWC of the materials increased upon pMPC modification, further improving upon increasing pMPC chain length. The contact angle was as low as 16.04 ± 2.37º for pMPC-50 surfaces and complete wetting for pMPC-100. Finally, the single protein adsorption using lysozyme and bovine serum albumin (BSA) showed significantly decreased protein levels for pMPC-50/100 lenses, as much as 83% (p 0.00036) for lysozyme and 73% (p 0.0076) for BSA, with no significant difference upon chain length variation. The aforementioned data demonstrates that the novel polymer has potential in providing an anti-fouling and extremely wettable surface, specifically regarding silicone hydrogel CL surfaces. / Thesis / Master of Applied Science (MASc)

Pb(II) removal is imperative due to its inherent toxicity at low levels and its tendency to accumulate in ecosystems. Conductive carbonaceous nanomaterials (CCNs), such as carbon nanotubes (CNTs) and carbon nanofibers (CNFs), have recently gained the interest of researchers due to their superior properties and ease of functionalization. The aim of this study is to utilize CCNs for Pb(II) removal within membrane technology and bioremediation strategies. Membranes have shown promise in their treatment abilities, producing excellent effluent quality while reducing plant footprints. The integration of CNTs within membrane technology provides an opportunity to couple its removal capacity with Pb(II) removal that exhibits regeneration capabilities. However, membrane fouling can be problematic for membrane longevity and regeneration. CNTs have also shown to be capable of mitigating fouling via electrostatic repulsion and pollutant degradation. However, little work has been conducted on its fabrication. In this work, CNTs were incorporated with poly(vinyl) alcohol (PVA) in thin film composites, where the effects of PVA chain length and degree of crosslinking were investigated. It was found that a pseudo-optimal coating can be obtained using 31-50kDa PVA with 10% crosslinking. This combination lead to a highly permeable, hydrophilic surface with good electrical conductivity that exhibited a molecular weight cut off of 2000kDa. Biosorption has shown promise in Pb(II) removal in the lab scale but its large-scale use is hindered from rapid saturation of binding sites and low regeneration abilities. Exoelectrogens were proposed as reactive biosorbents to couple biosorption with bioreduction in an attached growth configuration. CCNs were investigated as bacterial scaffolds, where their efficacy and Pb(II) dosage concentration was studied. It was found that CNFs were superior in removing Pb(II), exhibiting Pb(II) concentrations ≤0.10 ppm where removal increased when Pb(II) dosage increased from 0.5 to 5ppm. SEM-EDX analysis provided evidence that bioreduction dominated Pb(II) removal. A long-term study was further conducted using CNFs, revealing its robustness in long term removal over suspended growth reactors with a sustained removal of ≈ 80%. A numerical model was further proposed which exhibited a goodness of fit with an R-squared of 0.92. This model confirmed that bioreduction dominated Pb(II) removal and revealed biofilm thickness and Monod kinetics to be the main influential parameters on Pb(II) removal. / Thesis / Master of Applied Science (MASc)

Non-wetting surfaces mainly categorized into superhydrophobic (SHS), lubricant-infused (LIS) and solid-infused surfaces (SIS), by virtue of their superior water repellant properties have wide applications in several energy and environmental systems. In this dissertation, the role of non-wetting surfaces toward the enhancement of condensation effectiveness is analyzed by taking into consideration the tube side and shell side individual interfacial energy transport processes namely, drag reduction, convection heat transfer enhancement, fouling mitigation and dropwise condensation heat transfer. First, an analytical solution is developed for effective slip length and, in turn, drag reduction and friction factor on structured non-wetting surfaces. Secondly, by combining the solution for effective slip length on structured non-wetting surfaces and the fractal characterization of generic multiscale rough surfaces, a theoretical analysis of drag reduction, friction factor, and convection heat transfer enhancement is conducted for scalable non-wetting surfaces. Next, fractal representation of rough surfaces is used to theoretical derive the dropwise condensation heat transfer performance on SHS and novel SIS surfaces. The aspect of dynamic fouling mitigation properties of non-wetting surfaces is explored by conducting systematic experiments. Using Taguchi design of experiments, this work for the first time presents a closed formed relationship of fouling mitigation quantified in terms of asymptotic fouling resistance with Reynolds number, foulant concentration and viscosity of the infusion material that represents the different surface types in a unified manner. Furthermore, it was observed that LIS and SIS offer excellent fouling mitigation compared to SHS and conventional smooth surfaces, however only SIS owing to the presence of solid-like infusion materials is observed to be robust for practical applications. / Doctor of Philosophy / Inspired by the naturally occurring water repellant lotus leaf and pitcher plant, metallic surfaces have undergone engineering modifications to their native wetting properties. By generating roughness features ranging from nanometer to micrometer length scales, subjecting them to low surface energy treatments and by choosing an appropriate water repellant infusion material, the water repellant properties seen on lotus leaf and pitcher plant can be engineered. Such water repellant (non-wetting) surface fabrication methods are widely available in the literature however very few are scalable to surface types (e.g. copper, aluminum etc.), surface size (millimeters to meters) and shape (plain, curved, inside of tubes etc.). In this work, considering scalable fabrication methods such as electrodeposition and chemical etching, a systematic analysis is conducted on enhancement of four interfacial processes that are a part of many industrial applications. First, the extent of water repellency by structured non-wetting surfaces for the flow of fluid (water) quantified in terms of effective slip length of flow is analytically derived. Using this theory and a self-similar (fractal) nature of the more generic rough surface designs, a theoretical analysis into the drag reduction, convection heat transfer enhancement on non-wetting surfaces is conducted. Next, using the fractal nature of the rough superhydrophobic surfaces (SHS) a theoretical investigation into dropwise condensation performance is used to derive bounds on condensation heat transfer enhancement. Through systematic experimental investigations, it is shown that a solid-infused surface (SIS) and lubricant-infused surfaces (LIS) which, respectively, incorporate a polymer and a slippery lubricant in the interstitial region of metallic asperities, exhibit superior dynamic mineral fouling mitigation performance compared to SHS and conventional smooth surfaces. In addition, it is demonstrated that SIS is a far robust and durable choice when compared to LIS for use in the long run.

Nonwetting surfaces including superhydrophobic (SHS) and liquid infused surfaces (SLIPS) exhibit diverse exceptional characteristics promoting numerous application opportunities. Engineered textured surfaces demonstrate multiple features including drag reduction, fouling reduction, corrosion resistance, anti-fogging, anti-icing, and condensation enhancement. Integrating these properties, nonwetting surfaces have shown significant potential in improving the efficiency of energy applications. The first part of the thesis work aims at developing a fundamental mathematical understanding of the wetting process on the solid surface followed by presenting fabrication methodologies specifically focused on metallic substrates. The second part of this thesis presents an exhaustive survey on recent advancements and researches about features of nonwetting surfaces that could be implemented in major industrial applications. To establish how realistically these features could enhance the real-life applications, the third part of this work investigates the dynamic performance and economic benefits of using textured surfaces fabricated using an electrodeposition process for condenser tubes in thermoelectric power plants. The textured surfaces are expected to provide enhanced performance by deterring fouling and promoting dropwise condensation of the steam on the shell side. Using a thermal resistance network of a shell and tube condenser, detailed parametric studies are carried out to investigate the effect of various design parameters on the annual condenser performance measured in terms of its electric energy output of a representative 550 MW coal-fired power plant. A cost modeling tool and a new Levelized cost of condenser (LCOC) metric have been developed to evaluate the economic and performance benefits of enhanced condenser designs. The LCOC is defined as the ratio of the lifetime cost of the condenser (and associated costs such as coating, operation and maintenance) to the total electric energy produced by the thermoelectric power plant. The physical model is coupled with a numerical optimization method to identify the optimal design and operating parameters of the textured tubes that minimizes LCOC. Altogether, the study presents the first effort to construct and analyze enhanced condenser design with textured tube surfaces on annual thermoelectric power plant performance and compares it against the baseline condenser design with plain tubes. / Master of Science / Liquid repellant surfaces have attracted lots of attention due to their numerous promising characteristics including promoting condensation, drag reduction, prohibiting fouling/deposition, corrosion, and fog/dew harvesting. These attributes have the potential to inspire a variety of applications for these surfaces in power plants, automotive and aviation industries, oils/organic solvents clean-up, fuel cells, solar panels, membrane distillation, stone/concrete protection, surgical fabrics, and biological applications, to name a few. Some of these applications have reached their potential for real-life implementation and more are still at the research phase needing more experimental and fundamental studies to get them ready. The first part of this study presents the fundamentals of the wetting process. Next, fabrication methods for metallic surfaces have been explored to identify the most scalable and cost-effective approaches which could be administered in large scale industrial applications. A comprehensive review of recent publications on features of nonwetting surfaces has been carried out and presented in the second part of this thesis. To establish how realistically these features could enhance the real-life applications of a thermo-economic a performance model is developed for a powerplant condenser in the third section. Through a simple and cost-effective electrodeposition process, the common condenser tubes are modified to achieve textured tubes with superhydrophobic properties. The influence of using textured tubes on the plant's performance and its economic benefits are investigated to predict the potential promises of nonwetting surfaces.

This dissertation introduces assembly of spherical particles as a novel topography-based anti-biofouling coating. It also provides new insights on the effects of surface topography, especially local curvature, on cell–surface and cell–cell interactions during the evolution of biofilms. I investigated the adhesion, colonization, and biofilm formation of the opportunistic human pathogen Pseudomonas aeruginosa on a solid coated in close-packed spheres of polystyrene, using flat polystyrene sheets as a control. The results show that, whereas flat sheets are covered in large clusters after one day, a close-packed layer of 630–1550 nm monodisperse spheres prevents cluster formation. Moreover, the film of spheres reduces the density of P. aeruginosa adhered to the solid by 80%. Our data show that when P. aeruginosa adheres to the spheres, the distribution is not random. For 630 nm and larger particles, P. aeruginosa tends to position its body in the confined spaces between particles. After two days, 3D biofilm structures cover much of the flat polystyrene, whereas 3D biofilms rarely occur on a solid with a colloidal crystal coating of 1550 nm spheres. On 450 nm colloidal crystals, the bacterial growth was intermediate between the flat and 1550 nm spheres. The initial preference for P. aeruginosa to adhere to confined spaces is maintained on the second day, even when the cells form clusters: the cells remain in the confined spaces to form non-touching clusters. When the cells do touch, the contact is usually the pole, not the sides of the bacteria. The observations are rationalized based on the potential gains and costs associated with cell-sphere and cell-cell contacts. I concluded that the anti-biofilm property of the colloidal crystals is correlated with the ability to arrange the individual cells. I showed that a colloidal crystal coating delays P. aeruginosa cluster formation on a medical-grade stainless-steel needle. This suggests that a colloidal crystal approach to biofilm inhibition might be applicable to other materials and geometries. The results presented in appendix 1 suggest that colloidal crystals can also delay adhesion of Methicillin resistant staphylococcus aureus (MRSA) while it supports selective adhesion of this bacterium to the confined spaces. / Ph. D.

This dissertation presents a detailed account of the study undertaken on the subject of fouling of Exhaust Gas Recirculator (EGR) coolers. The fouling process in EGR coolers is identified to be due to two primary reasons — deposition of fine soot particles and condensation of hydrocarbons known as dry soot and wet soot fouling, respectively. Several numerical simulations are performed to study the fouling process. Preliminary analysis of the particle forces for representative conditions reveal that drag, thermophoresis and Brownian forces are the significant transport mechanisms and among them, the deposition process is dominated by thermophoresis. Soot deposition in a representative turbulent plain channel shows a direct relationship of the amount of deposition with the near-wall temperature gradient. Subsequently, periodic and developing flow simulations are performed on a wavy channel geometry, a common EGR design for various Reynolds numbers and thermal boundary conditions. Constant heat flux boundary condition is used in the periodic fully-developed calculations, which assist in establishing various deposition trends. The wavy nature of the walls is noted to affect the fouling process, resulting in specific deposition patterns. For the lower Reynolds number flows, significantly higher deposition is observed due to the higher particle residence times. On the other hand, the developing flow calculations facilitate the use of wall temperature distributions that typically exist in EGR coolers. The linear dependence of the amount of deposition on the near-wall temperature gradient or in other words, the heat flux, is ascertained. It is also observed in all the calculations, that for the sub-micron soot particles considered, the deposition process is almost independent of the particle size. In addition, the nature of the flow and heat transfer characteristics and the transition to turbulence in a developing wavy channel are studied in considerable detail. Finally, a study on the condensation of heavy hydrocarbons is undertaken as a post-processing step, which facilitates the prediction of the spatial distribution and time-growth of the combined fouling layer. From the calculations, the maximum thickness of the dry soot layer is observed to be near the entrance, whereas for the wet soot layer, the peak is found to be towards the exit of the EGR cooler. Further, parametric studies are carried out to investigate the effect of various physical properties and inlet conditions on the process of fouling. / Master of Science