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Fouling is the accumulation of unwanted material on solid surfaces to the detriment of function. The fouling materials can consist of either living organisms (biofouling) or a non-living substance (inorganic or organic). Fouling is usually distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system or plant performing a defined and useful function, and that the fouling process impedes or interferes with this function. Other terms used in the literature to describe fouling include: deposit formation, encrustation, crudding, deposition, scaling, scale formation, slagging, and sludge formation. The last six terms have a more narrow meaning than fouling within the scope of the fouling science and technology, and they also have meanings outside of this scope; therefore, they should be used with caution. Fouling phenomena are common and diverse, ranging from fouling of ship hulls, natural surfaces in the marine environment (marine fouling), fouling of heat-transfer components through ingredients contained in the cooling water or gases, and even the development of plaque or calculus on teeth, or deposits on solar panels on Mars, among other examples. This article is primarily devoted to the fouling of industrial heat exchangers, although the same theory is generally applicable to other varieties of fouling. In the cooling technology and other technical fields, a distinction is made between macro fouling and micro fouling. Of the two, micro fouling is the one which is usually more difficult to prevent and therefore more important. ==Components subject to fouling== Following are examples of components that may be subject to fouling and the corresponding effects of fouling: *Heat exchanger surfaces – reduces thermal efficiency, decreases heat flux, increases temperature on the hot side, decreases temperature on the cold side, induces under-deposit corrosion, increases use of cooling water; *Piping, flow channels – reduces flow, increases pressure drop, increases upstream pressure, increases energy expenditure, may cause flow oscillations, slugging in two-phase flow, cavitation; may increase flow velocity elsewhere, may induce vibrations, may cause flow blockage; *Ship hulls – creates additional drag, increases fuel usage, reduces maximum speed;〔"Marine fouling and its prevention"; prepared for Bureau of Ships, Navy Dept, Woods Hole Oceanographic Institution, United States, Navy Dept. Bureau of Ship, 1952. ((pdf) )〕 *Turbines – reduces efficiency, increases probability of failure; *Solar panels – decreases the electrical power generated; *Reverse osmosis membranes – increases pressure drop, increases energy expenditure, reduces flux, membrane failure (in severe cases);〔Siobhán Francesca E. Boerlage, "Scaling and Particulate Fouling in Membrane Filtration Systems", Taylor & Francis; 2001, ISBN 90-5809-242-9 ((Google books) )〕 *Electrical heating elements – increases temperature of the element, increases corrosion, reduces lifespan; *Nuclear fuel in pressurized water reactors – axial offset anomaly,〔Joshua M. Hawkes, "The Simulation and Study of Conditions Leading to Axial Offset Anomaly in Pressurized Water Reactors", Georgia Institute of Technology Master of Science Thesis, December 2004. ((pdf) )〕 may need to de-rate the power plant; *Injection/spray nozzles (e.g., a nozzle spraying a fuel into a furnace) – incorrect amount injected, malformed jet, component inefficiency, component failure; *Venturi tubes, orifice plates – inaccurate or incorrect measurement of flow rate; *Pitot tubes in airplanes – inaccurate or incorrect indication of airplane speed; *Spark plug electrodes in cars – engine misfiring;〔"Spark Plug Faces", brochure "Bosch Spark Plugs 0307", Part 1 ((pdf) )〕 *Production zone of petroleum reservoirs and oil wells – decreased petroleum production with time; plugging; in some cases complete stoppage of flow in a matter of days;〔G.A. Mansoori "Physicochemical Basis of Arterial Blockage / Fouling. Prediction and Prevention." Department of Chemical Engineering, University of Illinois at Chicago, on-line publication, September 2001 ((pdf) )〕 *Teeth – promotes tooth or gum disease, decreases aesthetics; *Living organisms – deposition of excess minerals (e.g., calcium, iron, copper) in tissues is (sometimes controversially) linked to aging/senescence. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fouling」の詳細全文を読む スポンサード リンク
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