• Membrane Journal
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• v.12 no.2
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• pp.55-66
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• 2002

fouling phenomena of ion exchange membranes were reviewed for improved design and operation of electodialysis. The membrane fouling index for electrodialysis (EDMFI) was defined for the quantitative analysis of fouling potential as an analogy to the pressure-driven membrane process. fouling phenomena were compared in the electrodialysis experiments with inorganic foulant (silica sol) and organic foulants (humate and bovine serum albumin (BSA)), and their fouling potentials were analyzed using the fouling index. The comparison showed that the EDMFI could be used as a quantitative measure of the fouling tendency in electrodialysis processes. As a novel fouling mitigation method, square wave power was reported to be effective in electrodialysis with organic foulants. The square wave powers having the pulsed electric field enabled to reduce the membrane fouling significantly at an optimal frequency.

• Membrane Journal
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• v.30 no.5
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• pp.342-349
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• 2020

In this study, we suggest conditions to reduce fouling in capacitive deionization (CDI) caused by alginic acid sodium salt, one of the most common fouling-causing substances in natural water and wastewater management. First, NaCl is used as feed material, which is selected as the control of the experiment. As expected, fouling phenomena is not observed from NaCl. On the other hand, when alginic acid sodium salt is added to the inlet, the fouling phenomena can be observed. In order to minimize the fouling phenomena, the feed concentration of alginic acid sodium salt, applied potential during desorption process, and duration of applied potential to our CDI cell are controlled. With 7 mg/L of feed stream concentration, CDI performed using 1.2 V for 1 min during adsorption followed by desorption with -2 V for 1 min exhibited the highest alginic acid salt removal efficiency reaching 50.07%.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.121-139
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• 2008

For mechanical drive steam turbines, the investigation results of corrosion fatigue phenomena in the transient zone are introduced, including basic phenomena on expansion line and actual design and damage experience. These results were analyzed from the standpoint of stress intensity during the start of cracking. In order to resolve such problems, preventive coating and blade design methods against fouling and corrosive environments are developed. Detailed evaluation test results are given for coating performance using a unique test procedure simulating fouling phenomena and washing conditions. Finally, the results of the successful modification of internals and on-line washing results on site are introduced.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1721-1729
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• 2001

The performance of gas turbines is decreased as their operating hours increase. Fouling in the axial compressor is one of main reasons for the performance degradation of gas turbine. Airborne particles entering with air at the inlet into compressor adhere to the blade surface and result in the change of the blade shape, which is closely and sensitively related to the compressor performance. It is difficult to exactly analyze the mechanism of the compressor fouling because the growing process of the fouling is very slow and the dimension of the fouled depth on the blade surface is very small compared with blade dimensions. In this study, an improved analytic method to predict the motion of particles in compressor cascades and their deposition onto blade is proposed. Simulations using proposed method and their comparison with field data demonstrate the feasibility of the model. It if found that some important parameters such as chord length, solidity and number of stages, which represent the characteristics of compressor geometry, are closely related to the fouling phenomena. And, the particle sloe and patterns of their distributions are also Important factors to predict the fouling phenomena in the axial compressor of the gas turbine.

• The KSFM Journal of Fluid Machinery
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• v.6 no.3 s.20
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• pp.36-43
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• 2003

Operating performance of industrial gas turbines in combined cycle power plants depends upon atmospheric conditions. Compressor fouling caused by airborne particles in the atmosphere and their adhesions on compressor blades is one of critical phenomena related to the performance degradation of industrial gas turbines. Compressor fouling provokes increase of pressure loss in inlet duct, decrease of mass flow rate of intake air and decrease of compressor stage efficiency. In this study, impacts of compressor fouling on the performance of an industrial gas turbine operating at design point condition are investigated analytically. As results, it is found that the reduction of produced power with decreased mass flow rate of intake air caused by narrowed flow area by the adhesion of airborne particles on compressor blades is the most dominant impact on the gas turbine performance by the compressor fouling phenomena.

• Membrane Journal
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• v.29 no.5
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• pp.276-283
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• 2019

In this study, The experiments of the confirmation of the fouling phenomena in CDI process and the establishment of its removal process conditions were carried out. The foulant concentrations of humic acid sodium salt (HA) added to the feed solution were 5, 10, 15 mg/L, respectively. The occurrence of fouling under the certain adsorption/desorption conditions could be confirmed with an increase in adsorption and desorption concentration curve over time. Both the voltage and time in adsorption and desorption processes were changed to eliminate the fouled pollutants. Typically, the fouling removal condition was found at the adsorption condition 1.2 V/5 min and the desorption condition -3 V/2 min, respectively.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.443-452
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• 1996

Fouling is caused by sedimentation and corrosion of polymer, heavy paraffine, chemicals, heavy organics, asphaltene, etc. in the entire chemical process of heat exchanger, boiler, desalter, etc. Fouling phenomena remains a serious operating problem which results in increased energy consumption, increased pressure drops, reduction or complete loss of products yield, and increased maintenance costs. In order to calculate the separated amounts of foulants and to control the fouling process, the predictive model is developed which is based on Scott & Magat polymer solution theory, Peng-Robinson EOS, BWR EOS, and continuous and multicomponent thermodynamics.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.49-54
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• 2003

Scale is formed when hard water is heated or cooled in heat transfer equipments such as heat exchangers, condensers, evaporators, cooling towers, boilers, and pipe walls. When scale deposits in a heat exchanging surface, it is traditionally called fouling. The objective of the present study was to compare the fouling characteristics of river and tap water in a heat exchanging model. FromtheSEM analyses for tap water the $calciteformofCaCO3_{3}$ was formed. For river water, however, the $aragoniteCaCO_{3}$ wasformed.In order to investigate velocity effects on the fouling characteristics in the heat exchanging model, the inlet velocity was varied with 0.5, 1.0 and 1.5 m/s, respectively. The fouling characteristics of river water were quite different from those of tap water. For the case of the 'velocity of 1.5m/s', the overall heat transfer coefficient was reduced up to 26% than that of the 'velocity of 0.5m/s'

• Membrane Journal
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• v.27 no.4
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• pp.291-312
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• 2017

Seawater desalination is currently considered to be one of the primary technologies to resolve the global water scarcity problem. A basic understanding of membrane filtration phenomena is significant not only for further technological development but also for integrated design, optimal control, and long-term maintenance. In this vein, the present work reviews the major transport and filtration models, specifically related to reverse osmosis phenomena, provides theoretical insights based on statistical mechanics, and discusses model-based physical meanings as related to their practical implications.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.1
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• pp.73-80
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• 2004

This study investigated the phenomena of membrane fouling by NOM and the effect of the fouling on removal of micro-pollutants. NOM has a great effect on decline of permeate flux. Permeate flow rate was reduced by 88% in RO and 34.8% in NF for 323hr operation period. Removal rate of $UV_{254}$, is 87.4% in RO and 78.5% in NF and removal rate of DOC is 42.7% in RO and 32.9% in NF for 2mg/l humic acid. Removal efficiency of the micro-pollutants by the RO and NF membranes fouled by humic acid was mostly lower than that by the new membrane. The concentration polarization which affects the flux and the rejection was thought to occur in the active layer of the membrane, as the membrane was getting fouled.