Academic literature on the topic 'Fouling interaction'
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Journal articles on the topic "Fouling interaction"
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Sun, Chunyi, Na Zhang, Fazhan Li, Guoyi Ke, Lianfa Song, Xiaoqian Liu, and Shuang Liang. "Quantitative Analysis of Membrane Fouling Mechanisms Involved in Microfiltration of Humic Acid–Protein Mixtures at Different Solution Conditions." Water 10, no. 10 (September 22, 2018): 1306. http://dx.doi.org/10.3390/w10101306.
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A systematical quantitative understanding of different mechanisms, though of fundamental importance for better fouling control, is still unavailable for the microfiltration (MF) of humic acid (HA) and protein mixtures. Based on extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) theory, the major fouling mechanisms, i.e., Lifshitz–van der Waals (LW), electrostatic (EL), and acid–base (AB) interactions, were for the first time quantitatively analyzed for model HA–bovine serum albumin (BSA) mixtures at different solution conditions. Results indicated that the pH, ionic strength, and calcium ion concentration of the solution significantly affected the physicochemical properties and the interaction energy between the polyethersulfone (PES) membrane and HA–BSA mixtures. The free energy of cohesion of the HA–BSA mixtures was minimum at pH = 3.0, ionic strength = 100 mM, and c(Ca2+) = 1.0 mM. The AB interaction energy was a key contributor to the total interaction energy when the separation distance between the membrane surface and HA–BSA mixtures was less than 3 nm, while the influence of EL interaction energy was of less importance to the total interaction energy. The attractive interaction energies of membrane–foulant and foulant–foulant increased at low pH, high ionic strength, and calcium ion concentration, thus aggravating membrane fouling, which was supported by the fouling experimental results. The obtained findings would provide valuable insights for the quantitative understanding of membrane fouling mechanisms of mixed organics during MF.
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Gray, S. R., C. B. Ritchie, and B. A. Bolto. "Effect of fractionated NOM on low-pressure membrane flux declines." Water Supply 4, no. 4 (December 1, 2004): 189–96. http://dx.doi.org/10.2166/ws.2004.0077.
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The membrane fouling characteristics of natural organic matter (NOM) were assessed using single polypropylene hollow fibre membranes of pore size 0.2 μm. The membranes were liquid backwashed every 30 minutes and filtration runs of up to 48 hours (≤8 litres) were conducted. The NOM samples were fractionated into different chemical classes based on their adsorption properties. For the two waters investigated, the hydrophobic components were the major foulant for one water, and the hydrophilics were the major foulant for the other. Interaction between the strongly hydrophobic and weakly hydrophobic fractions was significant for one water, but the extent of interaction between these fractions was minor for the other. The long term membrane fouling characteristics could not always be deduced from short term fouling trials.
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Yan, Linlin, Ruixue Li, Yu Song, Yanping Jia, Zheng Li, Lianfa Song, and Haifeng Zhang. "Characterization of the Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Evolution of the Foulants’ Composition and Aggregation Ability." Membranes 9, no. 7 (July 16, 2019): 85. http://dx.doi.org/10.3390/membranes9070085.
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In this study, the characteristics of membrane foulants were analyzed with regard to morphology, composition, and aggregation ability during the three stages of transmembrane pressure (TMP) development (fast–slow–fast rise in TMP) in a steady operational membrane bioreactor (MBR). The results obtained show that the fouling layer at the slow TMP-increase stage possessed a higher average roughness (71.27 nm) and increased fractal dimension (2.33), which resulted in a low membrane fouling rate (0.87 kPa/d). A higher extracellular DNA (eDNA) proportion (26.12%) in the extracellular polymeric substances (EPS) resulted in both higher zeta potential (-23.3 mV) and higher hydrophobicity (82.3%) for initial foulants, which induced and increased the protein proportion in the subsequent fouling layer (74.11%). Furthermore, the main composition of the EPS shifted from protein toward polysaccharide dominance in the final fouling layer. The aggregation test confirmed that eDNA was essential for foulant aggregation in the initial fouling layer, whereas ion interaction significantly affected foulant aggregation in the final fouling layer.
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Mahlangu, Oranso Themba, and Bhekie Brilliance Mamba. "Interdependence of Contributing Factors Governing Dead-End Fouling of Nanofiltration Membranes." Membranes 11, no. 1 (January 12, 2021): 47. http://dx.doi.org/10.3390/membranes11010047.
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Cake-enhanced concentration polarization (CECP) has been ascribed as the main cause of flux decline in dead-end filtration. An unfamiliar approach was used to investigate the role of CECP effects in the fouling of a nanofiltration membrane (NF-270) that poorly reject salts. Membrane–foulant affinity interaction energies were calculated from measured contact angles of foulants and membrane coupons based on the van der Waals/acid–base approach, and linked to resistance due to adsorption (Ra). In addition, other fouling mechanisms and resistance parameters were investigated using model organic and colloidal foulants. After selection, the foulants and membranes were characterized for various properties, and fouling experiments were conducted under controlled conditions. The fouled membranes were further characterized to gain more understanding of the fouling layer properties and flux decline mechanisms. Sodium alginate and latex greatly reduced membrane permeate flux as the flux declined by 86% and 59%, respectively, while there was minor flux decline when aluminum oxide was used as model foulant (<15% flux decline). More flux decline was noted when fouling was conducted with a combination of organic and colloidal foulants. Contrary to other studies, the addition of calcium did not seem to influence individual and combined fouling trends. Foulants adsorbed more on the membrane surface as the membrane–foulant affinity interactions became more attractive and pore blocking by the foulants was not important for these experiments. Hydraulic resistance due to cake formation (Rc) had a higher contributing effect on flux decline, while CECP effects were not substantial.
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Li, Zihe, Chongde Wu, Jun Huang, Rongqing Zhou, and Yao Jin. "Membrane Fouling Behavior of Forward Osmosis for Fruit Juice Concentration." Membranes 11, no. 8 (August 11, 2021): 611. http://dx.doi.org/10.3390/membranes11080611.
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Forward osmosis (FO) technology has a broad application prospect in the field of liquid food concentration because of the complete retention of flavor components and bioactive substances. Membrane fouling is the main obstacle affecting the FO performance and concentration efficiency. This work systematically investigated the membrane fouling behavior of the FO process for fruit juice concentration elucidated by the models of resistance-in-series, xDLVO theory and FTIR analysis. The results show that the AL-FS mode was more suitable for concentrating orange juice. Increasing the cross-flow rate and pretreatment of feed solutions can effectively improve the water flux and reduce the fouling resistance. The ATR-FTIR analysis revealed that the fouling layer of orange juice was mainly composed of proteins and polysaccharides, and the pretreatment of microfiltration can greatly reduce the content of the major foulant. There was an attractive interaction between the FO membrane and orange juice foulants; by eliminating those foulants, the microfiltration pretreatment then weakened such an attractive interaction and effectively prevented the fouling layer from growing, leading to a lower process resistance and, finally, resulting in a great improvement of concentration efficiency.
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Wang, Qiaoying, Zhiwei Wang, Chaowei Zhu, Xiaojie Mei, and Zhichao Wu. "Assessment of SMP fouling by foulant–membrane interaction energy analysis." Journal of Membrane Science 446 (November 2013): 154–63. http://dx.doi.org/10.1016/j.memsci.2013.06.011.
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Liu, Yaolin, and Baoxia Mi. "Combined fouling of forward osmosis membranes: Synergistic foulant interaction and direct observation of fouling layer formation." Journal of Membrane Science 407-408 (July 2012): 136–44. http://dx.doi.org/10.1016/j.memsci.2012.03.028.
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Han, Soo-Jin, and Jin-Soo Park. "Understanding Membrane Fouling in Electrically Driven Energy Conversion Devices." Energies 14, no. 1 (January 3, 2021): 212. http://dx.doi.org/10.3390/en14010212.
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Positively charged (cetylpyridinium chloride), negatively charged (sodium dodecyl sulfate), and non-charged (polyethylene glycol) surfactants are used as potential foulant in reverse electrodialysis systems supplying seawater and river freshwater. Fouling tendency of the foulants to ion-exchange membranes is investigated in terms of the adsorption by electromigration, electrostatic attraction, and macromolecule interaction in reverse electrodialysis systems. According to theoretical prediction of fouling tendency, charged foulants in seawater streams could foul ion-exchange membranes significantly. However, the worst fouling behavior is observed when the charged foulants are present in river streams. As a result of zeta potential measurement, it is found that the Debye length of the charged foulants decreases due to the higher ionic strength of seawater streams and causes to lower net electrostatic effect. It finally results in less fouling tendency in reverse electrodialysis.
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Halvey, Alex Kate, Brian Macdonald, Abhishek Dhyani, and Anish Tuteja. "Design of surfaces for controlling hard and soft fouling." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2138 (December 24, 2018): 20180266. http://dx.doi.org/10.1098/rsta.2018.0266.
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In this review, we present a framework to guide the design of surfaces which are resistant to solid fouling, based on the modulus and length scale of the fouling material. Solid fouling is defined as the undesired attachment of solid contaminants including ice, clathrates, waxes, inorganic scale, polymers, proteins, dust and biological materials. We first provide an overview of the surface design approaches typically applied across the scope of solid fouling and explain how these disparate research efforts can be united to an extent under a single framework. We discuss how the elastic modulus and the operating length scale of a foulant determine its ability or inability to elastically deform surfaces. When surface deformation occurs, minimization of the substrate elastic modulus is critical for the facile de-bonding of a solid contaminant. Foulants with low modulus or small deposition sizes cannot deform an elastic bulk material and instead de-bond more readily from surfaces with chemistries that minimize their interfacial free energy or induce a particular repellant interaction with the foulant. Overall, we review reported surface design strategies for the reduction in solid fouling, and provide perspective regarding how our framework, together with the modulus and length scale of a foulant, can guide future antifouling surface designs. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology’.
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Xiao, Ping, Weijun Zhang, Feng Xiao, Zhe Bi, and Dongsheng Wang. "A novel approach using a fouling index to evaluate NOM fouling behavior in a low pressure ultrafiltration process." Water Supply 14, no. 2 (September 13, 2013): 196–204. http://dx.doi.org/10.2166/ws.2013.189.
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A fouling index (FI) was introduced as a novel approach to investigate natural organic matter (NOM) fouling behavior in a low pressure membrane ultrafiltration process. Humic acid (HA), bovine serum albumin (BSA) and sodium alginate (SA), were used in the experiments. According to FI values, fouling was caused by NOM in two steps: a fast fouling process followed by a slow one. FI of the fast stage (FIF) was much greater than that of the slow one (FIS), showing the initial interaction would play a significant role in the fouling process over a short time. The results of mass balance suggested that a small fraction of DOC was responsible for membrane fouling caused by adsorption. Furthermore, both hydrophobic interaction and electrostatic interaction between NOM and the membrane determined the fouling behavior. Only a portion of foulants was removed after hydraulic washing. The sequence of NOM causing irreversible fouling was BSA > HA > SA, and the sequence of irreversible fouling after alkaline cleaning was SA > BSA > HA. The variations of FI values were consistent with the results of mass balances and flux recovery, which confirmed the FI was a simple and effective tool to describe the membrane fouling process.
Dissertations / Theses on the topic "Fouling interaction"
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Magens, Ole Mathis. "Mitigating fouling of heat exchangers with fluoropolymer coatings." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287467.
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Fouling is a chronic problem in many heat transfer systems and results in the need for frequent heat exchanger (HEX) cleaning. In the dairy industry, the associated operating cost and environmental impact are substantial. Antifouling coatings are one mitigation option. In this work, the fouling behaviour of fluoropolymer, polypropylene and stainless steel heat transfer surfaces in processing raw milk and whey protein solution are studied. Methodologies to assess the economics of antifouling coatings are developed and applied. Two experimental apparatuses were designed and constructed to study fouling at surface temperatures around 90 °C. A microfluidic system with a 650 x 2000 µm flow channel enables fouling studies to be carried out by recirculating 2 l of raw milk. The apparatus operates in the laminar flow regime and the capability to probe the local composition of delicate fouling deposit $\textit{in-situ}$ with histological techniques employing confocal laser scanning microscopy. A larger bench-scale apparatus with a 10 x 42 mm flow channel was built to recirculate 17 l of solution in the turbulent flow regime which is more representative of conditions in an industrial plate HEX. Experimental results demonstrate that fluoropolymer coatings can reduce fouling masses from raw milk and whey protein solution by up to 50 %. Surface properties affect the structure and composition of the deposit. At the interface with apolar surfaces raw milk fouling layers are high in protein, whereas a strongly attached mineral-rich layer is present at the interface with steel. Whey protein deposits generated on apolar surfaces are more spongy and have a lower thermal conductivity and/or density than deposits on steel. The attraction of denatured protein towards apolar surfaces and the formation of a calcium phosphate layer on steel at later stages of fouling are explained with arguments based on the interfacial free energy of these materials in water. The financial attractiveness of coatings is considered for HEX subject to linearly and asymptotically increasing fouling resistance and using a spatially resolved fouling model. An explicit solution to the cleaning-scheduling problem is presented for the case of equal heat capacity flow rates in a counter-current HEX. Scenarios where the use of coatings may be attractive or where there is no financial benefit in cleaning a fouled exchanger are identified. Finally, experimental data are used to estimate the economic potential of fluoropolymer coated HEXs in the ultra-high-temperature treatment of milk. In the considered case, the value of a fluoropolymer coating inferred from the reduction in fouling is estimated to be around 2000 US$/m².
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Perry, Jeffrey L. "Fouling in silicon microchannel designs used for IC chip cooling and its mitigation /." Online version of thesis, 2008. http://hdl.handle.net/1850/6211.
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Kargar, Mehdi. "Controlling Microbial Colonization and Biofilm Formation Using Topographical Cues." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71741.
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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.
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Case, Rebecca Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Molecular- and culturebased approaches to unraveling the chemical cross-talk between Delisea pulchra and Ruegeria strain R11." Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences, 2006. http://handle.unsw.edu.au/1959.4/30394.
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Delisea pulchra is a red macroalga that produces furanones, a class of secondary metabolites that inhibit the growth and colonization of a range of micro- and macroorganisms. In bacteria, furanones specifically inhibit acyl homoserine lactone (AHL)- driven quorum sensing, which is known to regulate a variety of colonization and virulence traits. This thesis aims to unveil multiple aspects of the chemically mediated interactions between an alga and its bacterial flora. It was demonstrated that the quorum sensing genetic machinery of bacteria is laterally transferred, making traditional 16S rRNA gene based-diversity techniques poorly suited to identify quorum sensing species. Previous studies had shown that AHL-producing bacteria belonging to the roseobacter clade can be readily isolated from D. pulchra. Because of this, it was decided to use a roseobacter epiphytic isolate from this alga, Ruegeria strain R11, to conduct a series of colonization experiments on furanone free and furanone producing D. pulchra. Furanones were shown to inhibit Ruegeria strain R11's colonization and infection of D. pulchra. In addition, it was demonstrated that Ruegeria strain R11 has temperature-regulated virulence, similar to what is seen for the coral pathogen Vibrio shiloi. Rising ocean temperatures may explain bleached D. pulchra specimens recently observed at Bare Island, Australia. To assess whether quorum sensing is common within the roseobacter clade, cultured isolates from the Roseobacter, Ruegeria and Roseovarius genera were screened for AHL production. Half of the bacteria screened produced the quorum sensing signal molecules, AHLs. These AHLs were identified using an overlay of an AHL reporter strain in conjunction with thin layer chromatography (TLC). The prevalence of quorum sensing within the roseobacter clade, suggests that these species may occupy marine niches where cellular density is high (such as surface associated communities on substratum and marine eukaryotes). Diversity studies in marine microbial communities require appropriate molecular markers. The 16S rRNA gene is the most commonly used marker for molecular microbial ecology studies. However, it has several limitations and shortcomings, to which attention has been drawn here. The rpoB gene is an alternate ???housekeeping??? gene used in molecular microbial ecology. Therefore, the phylogenetic properties of these two genes were compared. At most taxonomic levels the 16S rRNA and rpoB genes offer similar phylogenetic resolution. However, the 16S rRNA gene is unable to resolve relationships between strains at the subspecies level. This lack of resolving power is shown here to be a consequence of intragenomic heterogeneity.
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Smith, Diane Elizabeth. "Adhesion of Mycobacteria: Capture, Fouling, Aggregation." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1542537888485749.
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Fernandez-Gonzalez, Victoria. "Fouling amphipods on marine aquaculture facilities: ecological interactions and potential applications and potential applications." Doctoral thesis, Universidad de Alicante, 2017. http://hdl.handle.net/10045/89091.
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Aquaculture facilities involve mooring a large amount of artificial structures in offshore areas, which are colonised by a wide group of marine organisms, forming characteristic fouling communities. Many studies have focused on determining what sessile organisms are able to settle on nets, ropes and buoys, owing to the specific problems they cause and their economic cost to the aquaculture industry. Although sessile fouling communities are well-studied from the point of view of controlling this community on aquaculture facilities, little is known about the epifaunal mobile species inhabiting these artificial structures. This thesis addresses the study of crustacean amphipods, which have been scarcely studied regarding their species composition and relation to the habitats created by the sessile species and despite being detected in high abundances. After the general introduction, which sets the study framework, Chapter 1 is a preliminary study on the composition of fouling assemblages on aquaculture facilities in the Mediterranean Sea, comparing them with others such as those in harbours or offshore structures. Therein, it is shown that fouling communities are made up of mainly bivalves, algae, hydroids and bryozoans and amphipods usually represent more than 80 % of motile fauna associated with these organisms. Moreover, amphipod assemblages are characterised by seven frequent and dominant species: Elasmopus rapax, Jassa marmorata, Jassa slatteryi, Ericthonius punctatus, Stenothoe tergestina, Caprella equilibra and Caprella dilatata. A quantitative study of amphipod densities is carried out in Chapter 2, where mean amphipod densities observed in fish farm fouling amounted to 176,000 ind.m-2 and reached maxima up to 1,000,000 ind.m-2. There, the role of the macro- and microhabitat in supporting such amphipod communities is explored. The effect of the modification of marine currents on pelagic communities due to the introduction of coastal infrastructures is analysed in Chapter 3. Therein, it was detected a retention effect on planktonic amphipods near such facilities, noticeable in the increased abundance of hyperiids and migrating amphipods from different benthic and floating habitats. The influence of fouling amphipods on other habitats is analysed in Chapters 4 and 5, it is shown that fish-farm fouling acts as a source population of amphipods dispersing towards both defaunated sediments in soft-bottoms and surrounding floating habitats. Finally, in the last chapter, based on the possibility of using wild fauna already growing in fish farms, the applicability of amphipods as an accessory culture is tested in an offshore integrated multi-trophic aquaculture (IMTA) system with finfish as main fed species. Throughout this thesis it has been shown that fish-farming activities affect the amphipod assemblage in several ways such as the establishment of high population densities or the intimate connectivity between different subpopulations. As a result, a new potential commercial application arises from the possibility of using them as biofilters of aquaculture wastes, within an off-coast integrated multitrophic aquaculture system, promoting a more sustainable development of aquaculture in the marine environment.Las estructuras artificiales que conforman las instalaciones de acuicultura en mar abierto suelen ser colonizadas por multitud de organismos marinos, que forman comunidades de fouling características en estas estructuras. Muchos estudios se han centrado en la descripción de los organismos sésiles que se desarrollan sobre cabos, redes y boyas de las instalaciones de acuicultura, debido a los problemas que generan para el cultivo y los costes adicionales que significan para la industria derivados de su necesaria eliminación. Sin embargo, aunque las comunidades de fouling sésiles han sido bien estudiadas desde el punto de vista de su control en las instalaciones de acuicultura, poco se sabe sobre la epifauna que habita estas estructuras artificiales. Esta tesis se centra en el estudio de los crustáceos anfípodos, los cuales aún no han sido estudiados en cuanto a la composición de especies y a su relación con los hábitats creados por los organismos sésiles, a pesar de haber sido detectados en grandes abundancias en las instalaciones de acuicultura. Después de una introducción general, que establece el marco de estudio, el capítulo uno es un estudio preliminar sobre las comunidades de fouling de las instalaciones de acuicultura en el Mediterráneo, comparándolas con las desarrolladas en otras estructuras artificiales como puertos o plataformas petrolíferas. En este capítulo, se demuestra que las comunidades de fouling están compuestas principalmente por bivalvos, algas, hidrozoos y briozoos y que más de un 80% de la fauna asociada a estos organismos son anfípodos. Además el poblamiento se caracteriza por la presencia de siete especies de anfípodos que son frecuentes y abundantes: Elasmopus rapax, Jassa marmorata, Jassa slatteryi, Ericthonius punctatus, Stenothoe tergestina, Caprella equilibra y Caprella dilatata. Un estudio cuantitativo de las densidades de estos anfípodos se lleva a cabo en el capítulo 2, donde se encuentra que la densidad media es de 176.000 ind.m-2, con máximos de más de 1.000.000 ind.m-2. Allí se explora también el papel de los macro y microhábitats en mantener dichas poblaciones de anfípodos. El efecto de la modificación de corrientes sobre las comunidades plantónicas debida a la instalación de las piscifactorías se analiza en el capítulo 3. En él, se detectó una retención de los anfípodos planctónicos cerca de las instalaciones, evidenciada por el incremento en las abundancias de hipéridos y de anfípodos migradores desde diferentes hábitats bentónicos flotantes. La influencia de las grandes densidades de anfípodos del fouling sobre otros hábitats se estudia en los capítulos 4 y 5, donde se observó que el fouling actúa como fuente de anfípodos migradores, exportando individuos que colonizan tanto sedimentos defaunados en el fondo marino como otros hábitats flotantes cercanos. Finalmente, en el último capítulo se analiza la posibilidad de aprovechar la producción natural y la conectividad observadas a través del cultivo de anfípodos como parte de un sistema de acuicultura multitrófica integrada (AMTI) en mar abierto con peces como especie principal. A lo largo de esta tesis, se demuestra que la acuicultura influencia las poblaciones de anfípodos marinos, tanto en el establecimiento de grandes densidades de población como en la conectividad entre las diferentes subpoblaciones. Como resultado, surge una nueva aplicación comercial de la posibilidad de usar los anfípodos del fouling como biofiltros, reciclando los residuos de la acuicultura dentro de un sistema de acuicultura multitrófica, garantizando así un desarrollo más sostenible de la acuicultura en el medio marino.
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Jenkins, Maggie F. "Indirect Food Web Interactions: Sea Otter Predation Linked to Invasion Success in a Marine Fouling Community." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/2000.
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Humans have caused grave ecological and economic damage worldwide through the introduction of invasive species. Understanding the factors that influence community susceptibility to invasion are important for controlling further spread of invasive species. Predators have been found to provide biotic resistance to invasion in both terrestrial and marine systems. However, predators can also have the opposite effect, and facilitate invasion. Therefore, recovery or expansion of native predators could facilitate the spread of invasive species. Needles et al. (2015) demonstrated that the threatened southern sea otter (Enhydra lutris nereis) facilitated the invasion of an exotic bryozoan, Watersipora subatra. However, the underlying mechanism was not fully understood. We tested the hypothesis that sea otter predation on Romaleon antennarium crabs indirectly facilitated the abundance of W. subatra. To do this, we collected weekly data on sea otter foraging and quantified the abundance of crabs in the sea otter diet. We also conducted a caging experiment, where we experimentally manipulated crab densities and limited otter access using exclusion cages on pier pilings in Morro Bay, CA. We used photoQuad image processing software to calculate the abundance of W. subatra on PVC panels within each treatment group. We found that crabs were the second most abundant prey item in Morro Bay, comprising 25.1% of the otter diet. Through the caging experiment, we found that W. subatra abundance significantly increased as crab densities decreased. Our results indicated that sea otters indirectly facilitated the invasion of W. subatra by reducing R. antennarium crab densities and sizes. Removal of crabs may release W. subatra from the disturbance caused by crab foraging behavior. Understanding the impacts of top predators in invaded ecosystems has important management implications, as recovery of predator populations could unintentionally benefit some non-native species. Therefore, management should focus first on prevention and second on early detection and eradication of invasive species likely to benefit from predator recovery.
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Al-Zebari, Nawar. "Production and characterisation of self-crosslinked chitosan-carrageenan polyelectrolyte complexes." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267918.
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Macromolecular biomaterials often require covalent crosslinking to achieve adequate stability and mechanical strength for their given application. However, the use of auxiliary chemicals may be associated with long-term toxicity in the body. Oppositely-charged polyelectrolytes (PEs) have the advantage that they can self-crosslink electrostatically and those derived from marine organisms are an inexpensive alternative to glycosaminoglycans present in the extracellular matrix of human tissues. A range of different combinations of PEs and preparation conditions have been reported in the literature. However, although there has been some work on complex formation between chitosan (CS) and carrageenan (CRG), much of the work undertaken has ignored the effect of pH on the consequent physicochemical properties of self-crosslinked polyelectrolyte complex (PEC) gels, films and scaffolds. Chitosan is a positively-charged polysaccharide with NH3+ side groups derived from shrimp shells and, carrageenan is a negatively-charged polysaccharide with OSO3- side groups derived from red seaweed. These abundant polysaccharides possess advantageous properties such as biodegradability and low toxicity. However, at present, there is no clear consensus on the cell binding properties of CS and CRG or CS-CRG PEC materials. The aim of this study was to explore the properties of crosslinker-free PEC gels, solvent-cast PEC films and freeze-dried PEC scaffolds based on CS and CRG precursors for medical applications. The objective was to characterise the effect of pH of the production conditions on the physicochemical and biological properties of CS-CRG PECs. Experimental work focused on the interaction between PEs, the composition of PECs, the rheological properties of PEC gels and the mechanical properties of PEC films and scaffolds. In addition, cell and protein attachment to the PEC films was assessed to determine their interactions in a biological environment. For biomedical applications, these materials should ideally be stable when produced such that they can be processed to form either a film or a scaffold and have mechanical properties comparable to those of collagenous soft tissues. FTIR was used to confirm PEC formation. Zeta potential measurements indicated that the PECs produced at pH 2-6 had a high strength of electrostatic interaction with the highest occurring at pH 4-5. This resulted in stronger intra-crosslinking in the PEC gels which led to the formation of higher yield, solid content, viscosity and fibre content in PEC gels. The weaker interaction at pH 7-12 resulted in higher levels of CS incorporated into the complex and the formation of inter-crosslinking through entanglements between PEC units. This resulted in the production of strong and stiff PEC films and scaffolds appropriate for soft tissue implants. The PECs prepared at pH 7.4 and 9 also exhibited low swelling and mass loss, which was thought to be due to the high CS content and entanglements. From the range of samples tested, the PECs produced at pH 7.4 appeared to show the optimum combination of yield, stability and homogeneity for soft tissue implants. Biological studies were performed on CS, CRG and PECs prepared at pH 3, 5, 7.4 and 9. All of the PE and PEC films were found to be non-cytotoxic. When the response of three different cell types and a high binding affinity protein (tropoelastin) was evaluated; it was found that the CS-CRG PEC films displayed anti-adhesive properties. Based on these experimental observations and previous studies, a mechanistic model of the anti-adhesive behaviour of PEC surfaces was proposed. It was therefore concluded that the CS-CRG PECs produced might be suitable for non-biofouling applications.
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Jin, J. "Lipid foulant interactions during the chromatographic purification of virus-like particles from Saccharomyces cerevisiae." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1302065/.
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The objective of this study was to understand the mechanism of lipid fouling in chromatography through the investigation of a hydrophobic interaction chromatography (HIC) operation. This was motivated by the need to understand this phenomenon during the manufacture of biological products such as vaccines. The systematic approach and novel analytical techniques employed create a unique platform to study fouling of other chromatographic adsorbents and process feed materials. HIC is employed as a primary capture step in the purification of yeast derived hepatitis R surface antigen (HBsAg), where the required cell disruption and detergent liberation steps release high levels of lipid content into the feed stream. From lipid- rich and lipid-depleted feedstocks, comparative analysis was able to quantify the deterioration in HIC performance (binding capacities, purities and recoveries) under successive cycles. Furthermore, a full mass balance on host lipids identified the highly hydrophobic triacylglyceride as the main foulant. Intra-particle distribution and progression of lipid fouling and its effects on material adsorption and diffusion were then examined under confocal laser scanning microscopy (CLSM). In addition, high- resolution scanning electron microscopy (SEM) images of the fouled bead (after 40 cycles) confirmed that a thick lipid layer was building up on the outer bead surface. Based on these findings, the mechanism of fouling was thought to be the rapid accumulation of lipid foulant at the rim of the bead, which was aggravated by the possible diffusion hindrance resulting from multi layer adsorption. Finally, pretreatments to reduce this mechanism of chromatography fouling were evaluated in terms of improvement on feed quality and HIC performance. Selective adsorbent polystyrene XAD-4 demonstrated promising lipid removal capabilities with satisfactory HBsAg VLP recoveries. The improved feed into the column resulted in a three-fold increase in product capacity, whilst the overall yield remained constant over 40 cycles.
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Shen, Mingchao. "Monocyte/macrophage and protein interactions with non-fouling plasma polymerized tetraglyme and chemically modified polystyrene surfaces : in vitro and in vivo studies /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8013.
Full textBooks on the topic "Fouling interaction"
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Theis, Mischa. Interaction of biomass fly ashes with different fouling tendencies. Åbo: Åbo Akademi, 2006.
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National Heat Transfer Conference (28th 1991 Minneapolis, Minn.). Fouling and enhancement interactions: Presented at the 28th National Heat Transfer Conference, Minneapolis, Minnesota, July 28-31, 1991. New York, N.Y: American Society of Mechanical Engineers, 1991.
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Chau-Lyan, Chang, Merkle C. L, and Lewis Research Center, eds. Solar rocket plume/mirror interactions. [Washington, D.C.]: National Aeronautics and Space Administration, 1991.
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Solar rocket plume/mirror interactions. [Washington, D.C.]: National Aeronautics and Space Administration, 1991.
Find full textBook chapters on the topic "Fouling interaction"
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Tanudjaja, Henry J., and Jia W. Chew. "Assessment of Oil Fouling by Oil–Membrane Interaction Energy Analysis." In Solid–Liquid Separation Technologies, 151–68. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003091011-7.
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Zydney, Andrew L. "Non-Specific Protein-Membrane Interactions: Adsorption and Fouling." In Biofunctional Membranes, 279–88. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4757-2521-6_19.
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Diaconu, Gabriela, and Thomas Schäfer. "Sensing Techniques Involving Thin Films for Studying Biomolecular Interactions and Membrane Fouling Phenomena." In Smart Membranes and Sensors, 145–60. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781119028642.ch5.
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"Bacterial Interactions with Marine Fouling Organisms." In Biofilms, 119–35. CRC Press, 2000. http://dx.doi.org/10.1201/9781482284157-13.
Full textConference papers on the topic "Fouling interaction"
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Oliveira, D. R., Maria Joao Vieira, Luis F. Melo, and M. M. Pinheiro. "INTERACTION BETWEEN DIFFERENT FOULING AGENTS IN WATER SYSTEMS." In International Heat Transfer Conference 9. Connecticut: Begellhouse, 1990. http://dx.doi.org/10.1615/ihtc9.1140.
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Kessler, Daniel, Jens Friedrichs, and Christian Werner-Spatz. "ON THE IMPACT OF FOULING ON THE STAGE INTERACTION IN A 2.5-STAGE COMPRESSOR." In GPPS Chania22. GPPS, 2022. http://dx.doi.org/10.33737/gpps22-tc-34.
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Jet engines and thus the compressor suffer operational, particle-based wear during their usage. The type of wear depends on the ambient conditions, the operating point, and the size of the particles. Fouling is one possible type of wear, consisting of the deposition of small particles on the blade’s surface together with moisture from the air or leaked fluids of the compressor, thereby increasing the surface roughness and the blade thickness. In order to better understand the effects of fouling, and especially the interaction of different affected compressor stages, investigations are carried out on a 2.5-stage test compressor to evaluate fouling in the compressor. Fouling is represented using a randomly distributed surface structure of hemispheres on both rotor rows. The roughness parameter Ra is based on surface measurements of a worn actual CFM-56 engine after operation. The results are compared to smooth rotor blades without coating. The effect on the compressor is evaluated by integral measurements of efficiency and pressure rise and by wake measurements with pneumatic 5-hole probes. The results show integral losses in efficiency and pressure rise and, depending on the combination of rough rotor rows, a redistribution of the stage work. The second stage compensates for some of the losses of a rough first stage rotor, reducing the negative effects of the fouling.
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Mamouri, Sina Jahangiri, Volodymyr V. Tarabara, and André Bénard. "A Wall Film Model for Membrane Fouling." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83298.
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Deoiling of produced or impaired waters associated with oil and gas production represents a significant challenge for many companies. Centrifugation, air flotation, and hydrocyclone separation are the current methods of oil removal from produced water [1], however the efficiency of these methods decreases dramatically for droplets smaller than approximately 15–20 μm. More effective separation of oil-water mixtures into water and oil phases has the potential to both decrease the environmental footprint of the oil and gas industry and improve human well-being in regions such as the Gulf of Mexico. New membrane separation processes and design of systems with advanced flow management offer tremendous potential for improving oil-water separation efficacy. However, fouling is a major challenge in membrane separation [2]. In this study, the behavior of oil droplets and their interaction with crossflow filtration (CFF) membranes (including membrane fouling) is studied using computational fluid dynamics (CFD) simulations. A model for film formation on a membrane surface is proposed for the first time to simulate film formation on membrane surfaces. The bulk multiphase flow is modeled using an Eulerian-Eulerian multiphase flow model. A wall film is developed from mass and momentum balances [3] and implemented to model droplet deposition and membrane surface blockage. The model is used to predict film formation and subsequent membrane fouling, and allow to estimate the actual permeate flux. The results are validated using available experimental data.
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Theis, Mischa, Bengt-Johan Skrifvars, Mikko Hupa, and Honghi Tran. "Fouling Tendency of Ash Resulting From Burning Mixtures of Biofuels." In 18th International Conference on Fluidized Bed Combustion. ASMEDC, 2005. http://dx.doi.org/10.1115/fbc2005-78019.
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Specified mixtures of peat with bark and peat with straw were burned in a lab-scale entrained flow reactor that simulates conditions in the superheater region of a biomass-fired boiler. Deposits were collected on an air-cooled probe that was inserted into the reactor at the outlet. For both mixtures, the deposition behaviour followed a non-linear pattern, which suggests that physico-chemical interaction between the ashes of the different fuels has taken place. The results indicate that it is possible to burn up to 30 wt-% bark (renewable biofuel and pulp mill waste) and up to 70 wt-% straw (renewable biofuel and agricultural waste) in mixtures with peat without encountering increased deposition rates in the reactor. The deposit composition was compared to the fuel ash composition using chemical fractionation analysis and SEM/EDX. While the composition of deposits obtained from pure fuels resembles the feed composition, a considerable change is observed in deposits obtained from mixtures. K and S compounds are attached to Si spheres and the substrate surface. The deposition rate is significantly lowered when removing K, S, Cl and Na in bark prior to burning by washing and mechanical/thermal dewatering.
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Oliani, Stefano, Nicola Casari, Michele Pinelli, Alessio Suman, and Mauro Carnevale. "Effect of Jets in Crossflow in Deposition Mitigation on Full 3D NGV With Endwall Features." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15367.
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Abstract Particle ingestion is a major concern for the operation of gas turbines. In the case of an aircraft, particle dispersed in the air ingested by the engine can threaten flight safety. Swallowed particles can erode or stick to aerodynamic surfaces. Both the occurrences translate in a reduction of performance due to variation in shape and in roughness of the aerodynamic surfaces. This work is devoted to the analysis of fouling, i.e. the deposition of particles over time. By observing that the deposition pattern is strongly influenced by the flow field in the nearby of the walls, the central idea of this work is to employ Active Flow Control (AFC) to mitigate fouling when emergency conditions are met by the aircraft. The proposed system will inject air bled from compressor discharge in front of the critical locations where fouling is supposed to occur. The present work aspires to lay the foundations for the development of such an AFC device, by focusing on the modified aerodynamics consequent to the introduction of the transverse jet. The potential of this device is evaluated quantitatively using CFD simulations. An energy-based sticking model, coupled with a mesh-morphing solver, is used to track the airfoil deposition thickness evolution in time. The work is two-fold: first, the dynamics of the interaction between flow structures and particle transport is addressed. Second, the attention is posed on correlating fouling pattern variation to the modified aerodynamics of the vane consequent to the introduction of the device. Three design concepts are investigated on the 3D test case geometry of an HPT NGV cascade. The counter-rotating vortex pair (CVP) is detected as the main responsible for jet-particle interaction. Finally, the jet impact on aerodynamic performance is also assessed.
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Jubery, Talukder Z., Shiv G. Kapoor, and John E. Wentz. "Effect of Inter-Particle Interaction on Particle Deposition in a Cross-Flow Microfilter." In ASME 2013 International Manufacturing Science and Engineering Conference collocated with the 41st North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/msec2013-1211.
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Recent studies show that inter-particle interaction can affect particle trajectories and particle deposition causing fouling in the microfilters used for metal working fluids (MWFs). Inter-particle interaction depends on various factors: particle geometry and surface properties, membrane pore geometry and surface properties, MWF’s properties and system operating conditions, etc. A mathematical model with a Langevin equation for particle trajectory and a hard sphere model for particle deposition has been used to study the effect of particle’s size, particle’s surface zeta potential, inter-particle distance, and shape of membrane pore wall surface on particle trajectory and its deposition on membrane pore wall. The study reveals that bigger particles have a lesser tendency to be deposited on membrane pore walls than smaller particles. The shape of the membrane pore wall surface can also affect the particle deposition behavior.
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Kargar, Mehdi, Jeff Saucke, Amrinder S. Nain, and Bahareh Behkam. "Bioinspired Anti-Biofilm Surfaces Based on Topographical Cues." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80847.
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Adhesion of bacteria to surfaces is the starting point for formation of biofilms, which tend to be significantly less responsive to antibiotics and antimicrobial stressors, compared with planktonic bacteria. The physicochemical properties of natural anti-biofilm surfaces are being actively studied to develop bioinspired anti-biofilm strategies. It has been shown that –majority of natural anti-biofilm surfaces have well organized micro/nanoscale surfaces features [1]. The difficulties associated with the manufacturing of well-defined and controlled nano-textured surfaces and complexity of the behaviour of microorganisms interacting with engineered surfaces has limited rigorous quantitative study of the state of adhesion of fouling microorganisms to engineered surfaces. The work presented here aims to advance the current understanding of cell-textured surface interaction with the ultimate goal of developing an anti-biofilm design framework based on topographical cues.
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Casari, Nicola, Michele Pinelli, and Alessio Suman. "An Innovative Approach Towards Fouling Modeling: Microscale Deposition Pattern and its Effect on the Flow Field." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76882.
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Solid particle ingestion is one of the main compressor degradation mechanisms for both heavy-duty and aero-propulsion gas turbines. Particles impacting the inner surfaces of the machine can stick there forming deposits. The presence of such deposits reflects on the reduction in performance of the machinery. Over last years, several methods have been developed in order to study the problem from the numerical standpoint. Examples of these techniques are the mesh morphing approach and the added-roughness-and-thickness method. In this work, an innovative procedure is proposed in order to evaluate the losses and the variation in the fluid flow due to the deposits. Particularly, an algorithm capable of determining the microscale deposition pattern has been developed. By using this methodology, a comprehensive analysis of the variation of the performance of the compressor over time can be carried out. The deposition severity and the subsequent roughness variation can be kept into account in a very detailed and precise fashion. Furthermore, this approach overcomes the difficulties that may arise by using a mesh morphing technique. The computational grid is not modified and thus its quality is retained, without re-meshing requirements, even for large deposits. The local roughness variation is accounted for without extra-effort. The procedure developed, shown here in deposition problems, can be easily extended to erosion or even icing problems. The only parameter to be changed is the model that takes care of the particle-wall interaction, using an erosion rather than an icing law.
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Ma, Lei, Fengzhong Sun, Wei Wei, Jiayou Liu, and Yuetao Shi. "The Interaction Effect Study of Ash Deposition and Acid Condensation on Low-Temperature Heat Transfer Surface in Boiler Flue Gas." In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3291.
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The ash deposition on low-temperature heat transfer surface is a key factor that deteriorates the heat transfer performance and leads to corrosion in the low pressure economizer. In the low temperature flue gas, ash deposition is closely related with acid condensation. The sulfuric acid vapor and water vapor contained in the flue gas will condense on heat transfer surface under low flue temperature, which will aggravate ash deposition. In order to evaluate the influence factors of ash deposition on low-temperature heat transfer surface, a laboratory experiment is carried out in this paper. The acid concentration of flue gas, the ash content, the ash component, the flue temperature and the temperature of heat transfer surface are considered to be the most important influence factors on ash deposition characteristics. The viscosity of ash deposition samples on the outer wall of the double-pipe is measured to describe ash deposition characteristics. The fouling factor is calculated. Meanwhile, the scanning electron microscope SEM is used to the analysis of ash samples obtained from the outer wall of the double-pipe. As conclusion, the changing regulation of viscosity of ash deposition on low-temperature heat transfer surface is obtained. (CSPE)
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Haskell, R. W. "Gas Turbine Compressor Operating Environment and Material Evaluation." In ASME 1989 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/89-gt-42.
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The reliability and performance of a gas turbine compressor is strongly dependent upon the environment in which it operates, the materials which are used, and the filtration system. Erosion and to a certain extent fouling can be controlled by the filtration system, but corrosion is largely controlled through site and material selection. The factors which determine the corrosivity of a site are humidity, the concentration of acid-forming gases, and the composition of particulates. The interrelationships of these factors are discussed with an aim of reducing their impact on compressor operation. A necessary condition for corrosion is the presence of moisture. The acidity of the moisture results from its interaction with the gases and particulates of the environment. The details of these interactions which are important to turbine operators are discussed. A considerable amount of corrosion testing of base materials and coatings has been performed and this is reviewed. A table is presented for selection of compressor materials based on the nature of the site environment and the type of compressor filtration.