{"id":2133,"date":"2021-04-13T13:12:17","date_gmt":"2021-04-13T13:12:17","guid":{"rendered":"https:\/\/wldstainless.com\/?p=2133"},"modified":"2021-04-13T13:14:08","modified_gmt":"2021-04-13T13:14:08","slug":"when-stainless-steel-bellows-used-in-shell-heat-exchanger","status":"publish","type":"post","link":"https:\/\/wldstainless.com\/cs\/when-stainless-steel-bellows-used-in-shell-heat-exchanger\/","title":{"rendered":"P\u0159i pou\u017eit\u00ed vlnovce z nerezov\u00e9 oceli v pl\u00e1\u0161\u0165ov\u00e9m v\u00fdm\u011bn\u00edku tepla"},"content":{"rendered":"

Vlnovcov\u00fd trubkov\u00fd v\u00fdm\u011bn\u00edk tepla je upgrade zalo\u017een\u00fd na p\u0159\u00edm\u00e9m (sv\u011btl\u00e9) trubkov\u00e9m v\u00fdm\u011bn\u00edku tepla. Konstrukce h\u0159ebene a \u017elabu vlny p\u0159eb\u00edr\u00e1 v\u00fdhody trubkov\u00e9ho v\u00fdm\u011bn\u00edku, jako je \u017eivotnost a bezpe\u010dnost, a z\u00e1rove\u0148 p\u0159ekon\u00e1v\u00e1 nedostatky, jako je \u0161patn\u00e1 schopnost p\u0159enosu tepla a snadn\u00e9 vytv\u00e1\u0159en\u00ed koteln\u00edho kamene. Principem je zlep\u0161it celkov\u00fd sou\u010dinitel prostupu tepla tak, aby se zmen\u0161ila po\u017eadovan\u00e1 plocha p\u0159enosu tepla, co\u017e m\u016f\u017ee p\u0159i stejn\u00e9m efektu p\u0159enosu tepla u\u0161et\u0159it materi\u00e1ly a sn\u00ed\u017eit hmotnost.<\/p>\n

Proto\u017ee t\u011blo m\u011bchu je zpracov\u00e1no lisov\u00e1n\u00edm za studena\u00a0sv\u011btl\u00e9 potrub\u00ed<\/a> sochoru, obecn\u011b se m\u00e1 za to, \u017ee t\u011blo m\u011bchu lze po vytvarov\u00e1n\u00ed zpevnit. Experiment stability vn\u011bj\u0161\u00edho tlaku ukazuje, \u017ee k nestabilit\u011b vlnit\u00e9 teplosm\u011bnn\u00e9 trubky pod vn\u011bj\u0161\u00edm tlakem doch\u00e1z\u00ed nejprve v p\u0159\u00edm\u00e9m \u00faseku trubky a vlnit\u00e1 trubka bude nestabiln\u00ed pouze tehdy, pokud bude vn\u011bj\u0161\u00ed tlak nad\u00e1le stoupat. To ukazuje, \u017ee stabilita vlnit\u00e9ho profilu je lep\u0161\u00ed ne\u017e stabilita p\u0159\u00edm\u00e9ho profilu a \u017ee kritick\u00fd tlak vlnit\u00e9ho profilu je vy\u0161\u0161\u00ed ne\u017e u p\u0159\u00edm\u00e9ho profilu.<\/p>\n

Experimenty ukazuj\u00ed, \u017ee ke zvln\u011bn\u00ed vzp\u011brn\u00e9 deformace do\u0161lo ve vlnov\u00e9m \u017elabu, zejm\u00e9na lok\u00e1ln\u00edm jednotliv\u00e9m \u017elabu, obecn\u011b ne v\u00edce ne\u017e dv\u011b \u017el\u00e1bky nestabilita sou\u010dasn\u011b, ukazuje, \u017ee stabilita h\u0159ebene vlny je lep\u0161\u00ed ne\u017e \u00fa\u017elab\u00ed, ale n\u011bkdy se tak\u00e9 m\u016f\u017ee objevit naopak, v procesu lisov\u00e1n\u00ed za studena je tlou\u0161\u0165ka \u017elabu i st\u011bny rovn\u00e9ho \u00faseku konstantn\u00ed, za studena je trubka ve skute\u010dnosti krat\u0161\u00ed.<\/p>\n

Existence vrchol\u016f a prohlubn\u00ed vln v m\u011bchu zvy\u0161uje \u00fa\u010dinek radi\u00e1ln\u00ed konvekce v\u00fdm\u011bny tepla v trubk\u00e1ch, jak je zn\u00e1zorn\u011bno na obr\u00e1zku n\u00ed\u017ee:<\/p>\n

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Radi\u00e1ln\u00ed konvekce m\u00e1 velk\u00fd vliv na celkov\u00fd sou\u010dinitel prostupu tepla, co\u017e je z\u00e1sadn\u00ed d\u016fvod n\u00edzk\u00e9 ceny a n\u00edzk\u00e9 hmotnosti dvoutrubkov\u00e9ho vlnovcov\u00e9ho v\u00fdm\u011bn\u00edku. Teplosm\u011bnn\u00e1 oblast trubka<\/a> povrch t\u011bla m\u011bchu a rovn\u00e9 trubky je velk\u00fd p\u0159i stejn\u00e9 d\u00e9lce, ale tato zm\u011bna je mnohem men\u0161\u00ed ne\u017e p\u0159\u00edsp\u011bvek zm\u011bny hodnoty koeficientu. Je jasn\u011b vid\u011bt, \u017ee rychlost proud\u011bn\u00ed p\u0159\u00edm\u00e9 (lehk\u00e9) trubice je v\u00fdrazn\u011b sn\u00ed\u017eena, kdy\u017e je bl\u00edzko st\u011bny trubky.<\/p>\n

Pl\u00e1\u0161\u0165ov\u00fd v\u00fdm\u011bn\u00edk tepla s vlnovcem m\u016f\u017ee ve srovn\u00e1n\u00ed s p\u0159\u00edm\u00fdm trubkov\u00fdm v\u00fdm\u011bn\u00edkem neust\u00e1le m\u011bnit rychlost a sm\u011br kapaliny za vzniku turbulence, \u010d\u00edm\u017e doch\u00e1z\u00ed k v\u00fdm\u011bn\u011b tepla se st\u011bnou, hrani\u010dn\u00ed efekt, kter\u00fd ovliv\u0148uje p\u0159enos tepla, ji\u017e nebude existovat. Celkov\u00fd koeficient prostupu tepla lze zv\u00fd\u0161it 2 ~ 3kr\u00e1t a skute\u010dn\u00fd provoz m\u016f\u017ee dos\u00e1hnout dokonce 5kr\u00e1t a hmotnost je n\u00edzk\u00e1, co\u017e je d\u016fvod, pro\u010d je cena vlnovcov\u00e9ho v\u00fdm\u011bn\u00edku tepla ni\u017e\u0161\u00ed ne\u017e cena tepla z p\u0159\u00edm\u00fdch trubek. v\u00fdm\u011bn\u00edk. Podle v\u00fdpo\u010dtu a praktick\u00fdch zku\u0161enost\u00ed je celkov\u00fd sou\u010dinitel prostupu tepla vlnovce o tlou\u0161\u0165ce 1 mm o 10% ni\u017e\u0161\u00ed ne\u017e u vlnovce o tlou\u0161\u0165ce 0,5 mm. Provozn\u00ed \u00fadaje stovek vlnovcov\u00fdch v\u00fdm\u011bn\u00edk\u016f ukazuj\u00ed, \u017ee tlou\u0161\u0165ka st\u011bny (t\u00e9m\u011b\u0159 v\u0161echny 0,5 mm) je hlavn\u00edm d\u016fvodem provozu 10 ~ 14 let bez v\u011bt\u0161\u00ed opravy nebo po\u0161kozen\u00ed.<\/p>\n

Krom\u011b toho m\u016f\u017ee vlnovcov\u00fd v\u00fdm\u011bn\u00edk \u00fa\u010dinn\u011b odolat n\u00e1razu vodn\u00edho r\u00e1zu. Pl\u00e1\u0161\u0165 dvoutrubkov\u00e9ho deskov\u00e9ho v\u00fdm\u011bn\u00edku je spojen dilata\u010dn\u00ed sp\u00e1rou. Pokud utrp\u00ed n\u00e1razy vodn\u00edho r\u00e1zu, bude dilata\u010dn\u00ed sp\u00e1ra \u0161patn\u011b um\u00edst\u011bna. To se d\u011bje jak u vlnovcov\u00fdch, tak u p\u0159\u00edm\u00fdch trubkov\u00fdch v\u00fdm\u011bn\u00edk\u016f tepla a deformace pl\u00e1\u0161t\u011b m\u016f\u017ee zp\u016fsobit zkroucen\u00ed trubky. Je to proto, \u017ee m\u011bch m\u00e1 v\u011bt\u0161\u00ed rozta\u017enost, elastick\u00e1 meze nap\u011bt\u00ed je p\u0159i deformaci velk\u00e1, to znamen\u00e1, \u017ee schopnost odol\u00e1vat nestabilit\u011b je v tomto p\u0159\u00edpad\u011b siln\u00e1. Ale v ka\u017ed\u00e9m p\u0159\u00edpad\u011b, v procesu instalace, aby se zabr\u00e1nilo v\u00fdskytu vodn\u00edho r\u00e1zu, lze prov\u00e9st pomoc\u00ed \u00fahlov\u00e9ho sedac\u00edho ventilu, zpo\u017ed\u011bn\u00ed sp\u00edna\u010de a dal\u0161\u00edch opat\u0159en\u00ed.<\/p>\n

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V\u00fdhody vlnovcov\u00e9ho v\u00fdm\u011bn\u00edku z nerezov\u00e9 oceli<\/h3>\n