Study of Temperature Fields at Sprinkled Smooth and Sandblasted Tube Bundle

a Co esponding au ho : k acik@ me. u b .cz S udy o Tempe a u e Fields a Sp inkled Smoo h and Sandblas ed Tube Bundle Pe K acík1,a, Ladisla Šnajdá ek1 and JiĜí Pospíšil1 1Ins i u e o Powe Enginee ing, B no Uni e si y o Technology, Facul y o Mechanical Enginee ing, Technická 2896/2, 616 69 B no, The Czech Republic Abs ac . The pape ocuses on he in luence o sp inkled ube su ace on dis ibu ion o empe a u e ields, i.e. he hea ans e coe icien on he ubes su ace. Two ypes o ubes ha e been es ed, a smoo h one and a sandblas ed one in pa icula . A ube bundle comp ises o hi een coppe ubes di ided in o wo ows and i is loca ed in a low p essu e chambe whe e acuum is gene a ed using an exhaus e ia ejec o . The liquid es ed was wa e a an absolu e p essu e in a chambe in be ween 97 kPa up o 10 kPa and a he mal g adien 55 o 30 °C. The low o he alling ilm liquid anged be ween ze o and 17 li es pe minu e. 1 In oduc ion A a ho izon al ube bundle sp inkled by a liquid o a low low a e, a hin liquid ilm is o med ha acili a es e ec i e hea ans e . As he liquid lows, he liquid phase is p omp ly sepa a ed om he apou phase which inc eases he hea ans e coe icien . This echnology is applied o ins ance a sea wa e dis illa ion. This dis illa ion p inciple is based on low empe a u es ha a y by ens o deg ees Cen ig a e bu i is necessa y o adequa ely lowe he p essu e o he a ea in which a ube bundle is posi ioned o enable e apo a ion. The ad an age o his me hod is ha i can u ilize low-po en ial was e hea o o he powe -p oducing p ocesses. The Eu opean coun ies and he USA emphasize sa ing he p ima y uel en e ing powe -p oducing p ocesses. Apa om boos ing e iciency o powe - p oducing p ocesses and lowe ing ene gy consump ion i is also possible o use he was e hea o coolness p oduc ion. The e a e wo p edominan echnologies o coolness p oduc ion. The i s me hod u ilizes comp esso cooling de ices which a e, howe e , e y hea y on elec ic powe . Abso p ion ci cula ion ep esen s hei easible al e na i e. Al hough being la ge and mo e expensi e, i consumes app oxima ely one i h o he elec ic powe . The basic elemen o a single-s age abso p ion ci cula ion consis s o wo exchange s ope a ing in a low-p essu e en i onmen – he abso be and he deso be . The hea ca ying agen 's s eam is cooled in he abso be , abso bed in o an abso ben ; excess hea mus be conduc ed away p ope ly. In a simpli ied way, i is a sp inkled exchange on he su ace o which he wa e s eam condensa es. The p ima y hea is supplied o he cycle in deso be , so he hea is p o ided o he cooling liquid and wa e boils a ube su ace. And i is he s udy o he modynamic mechanisms om he pe spec i e o sp inkle modes when supplying hea o a cooling liquid ha his pape ocuses on. 2 Sp inkle mode A liquid lowing h ough a ho izon al ube bundle may o m h ee basic sp inkle modes isible in Figu e 1. These a e he D ople mode (a), he Je mode (b) and he Memb ane (Shee ) mode (c). These h ee modes a e he eina e e e ed o as he "D", "J" and "S" modes. Figu e 1 Sp inkle Modes [1] Wi h an inc easing alling ilm liquid low a e he ansi ion om he D ople o he Je mode is de ined by he o ma ion o one s able column o liquid in among he d ople s ( his ansi ion mode will be he eina e e e ed o as he "DĺJ" mode). The ansi ion om he Je o he Memb ane (Shee ) mode is de ined by he connec ion o wo columns and hei o ma ion o a small iangula shee (he eina e e e ed o as This is an Open Access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License 2.0, which pe mi s un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed. DOI: 10.1051/ C Owned by he au ho s, published by EDP Sciences, 2014 , 02060 (2014) /201 67 epjcon EPJ Web o Con e ences 46702060 A icle a ailable a h p://www.epj-con e ences.o g o h p://dx.doi.o g/10.1051/epjcon /20146702060 he "JĺS" mode). In his mode, columns and lea es exis side by side. Wi h a dec easing alling ilm liquid low a e he e e se p ocess akes place. Tha means ha he o ma ion o a s able liquid low among he shee s is e e ed o as he Shee -Column s a e (he eina e e e ed o as he "SĺJ" mode) and he disin eg a ion o he i s column in he Column mode and i s eplacemen by d ople s changes he s a e o he Je -D ople mode (he eina e e e ed o as he "JĺD" mode). In case ha he ansi ion sp inkle mode is desc ibed wi hou an a ow ma king he di ec ion o he alling ilm liquid inc ease/dec ease bu wi h a dash, hen he change o he low a e is no conside ed. 2.1 alling ilm liquid low a e change A pa icula sp inkle mode is in luenced by a numbe o ope a ional pa ame e s. The i s o hem is he in luence o a change in he alling ilm liquid low a e inc ease/dec ease on he dis ance be ween he d ople columns, i.e. he equency o d ops, desc ibed in a s udy conduc ed a he Vic o ia Uni e si y (Aus alia) [4]. An expe imen al se was cons uc ed a his uni e si y in o de o e i y he nume ical model. I consis ed o h ee iden ical cylinde s posi ioned in a pa allel way one below he o he ( h ee diame e s we e es ed: 0.1 m, 0.05 m and 0.02 m). The sp inkle mode i sel was eco ded by a digi al came a eco de . The Figu e 2 illus a es he dependence o he d op equency (i.e. he numbe o d ops pe second o all on o he middle cylinde ) and he dimensionless wa eleng h (i.e. he wa eleng h desc ibing he dis ance be ween he d ople columns di ided by su ace ension, also e e ed o as capilla y cons an ) on he Reynolds numbe . Figu e 2 Dependence o d op equency and dimensionless wa eleng h on he Reynolds numbe [4] This Figu e shows hese wo quan i ies o a mono onously inc easing and dec easing low a e. Measu ing was conduc ed in he Reynolds numbe ange o 20 – 150 [-] and i was disco e ed ha he dependence o he equency on he Reynolds numbe is e y simila , howe e , when dec easing he low a e he d ops s a ed o sepa a e in a sligh ly slowe pace in compa ison wi h he inc easing low a e, which is isible pa icula ly in he Reynolds numbe ange o app ox. 50 – 100 [-]. The eason o hese sligh ly lowe alues o d ops sepa a ion can be deduc ed om he dimensionless wa eleng h whe e a he dec easing low a e he liquid a he middle cylinde ends o main ain he cu en s a e as long as possible, i.e. he dis ance be ween he d ople columns ge s e en sho e which na u ally esul s in he lowe numbe o d ops. A he Reynolds numbe o app ox. 70 [-] a u ning poin occu s whe e he low a e is dec eased o he ex en ha he dis ance be ween he d ople columns s a s o inc ease apidly, i.e. he d op equency s a s o dec ease sha ply. The in luence o he low a e changes a a ious diame e s o sp inkled ubes was also esea ched o ins ance by Hu and Jacobi [3]. To conduc hei esea ch hey ha e c ea ed an ae odynamic unnel o ac yla e anspa en plas ic o he c oss sec ion dimensions 203.2 x 304.8 mm whe e he speed o ai low mo ing in he opposi e di ec ion o he alling ilm liquid low anged be ween 1.0 and 15.0 mÂs-1. The ube bundle es ed consis ed o a dis ibu ion ube, a s abiliza ion ube ha was posi ioned 1.4 mm below he dis ibu ion ube, a es ed ube, a landing ube and a collec ing channel. The e we e ape u es o 1.0 mm diame e d illed in o he dis ibu ion ube a 1.5 mm spans along he leng h o 229 mm. The ube diame e s es ed we e 9.5; 12.7; 15.9; 19.0 and 22.2 mm. Fo he sp inkled ube bundle in a s ill a mosphe e ( lowing ai speed in he ube su oundings comes close o ze o) Hu and Jacobi [3] e i ied he con enience o dependence be ween he Reynolds numbe ha desc ibes a hyd odynamic low mode and he Galilei numbe ha desc ibes he liquid low esul ing om g a i a ion, o de ine he ansi ion o indi idual sp inkle modes. This dependence can be gene ally exp essed in he o m Re = Aڄ(Ga)B (1) whe e bo h dimensionless c i e ia co e se en physical pa ame e s al oge he ; i.e. he alling ilm liquid low a e, he alling ilm liquid dynamic iscosi y, he alling ilm liquid densi y, he alling ilm liquid su ace ension, he sp inkled ube diame e , he gap be ween he sp inkled ubes and he g a i a ional accele a ion. In he s ill mode i was disco e ed ha he ansi ions be ween he indi idual sp inkle modes a y wi h an inc easing and dec easing low a e and c i e ial equa ions we e de e mined o hese modes acco ding o he equa ion (1) whe e he "A" and "B" cons an s a e gi en in Table 1 oge he wi h a ela i e e o o each equa ion Figu e 3 desc ibes bo de s a inc easing and dec easing alling ilm liquid low a e acco ding o EPJ Web o Con e ences 02060-p.2 he men ioned equa ions a a mosphe ic p essu e and wa e empe a u es 30 °C and 55 °C, which co esponds on he basis o [9] o a modi ied Galilei numbe Ga0.25 § 476 and 751 [-]. Table 1 Coe icien s o equa ion (1) o de e mine he low mode acco ding o Hu and Jacobi [3] a) Inc easing low D ĺ D-J D-J ĺ J J ĺ J-S J-Sĺ S A B A B A B A B 0.121 0.284 0.159 0.282 1.880 0.222 2.088 0.220 (8.5 %) (6.6 %) (4.3 %) (4.2 %) b) Dec easing low S ĺ S-J S-Jĺ J J ĺ J-D J-Dĺ D A B A B A B A B 1.004 0.250 1.064 0.244 0.057 0.321 0.045 0.321 (3.9 %) (3.8 %) (8.4 %) (6.2 %) Figu e 3 Sp inkle mode bo de s a inc easing and dec easing low a e acco ding o Hu and Jacobi [3] 2.2 In luence o sp inkled ube diame e In he s udy men ioned abo e [4] he cylinde diame e in luence on he d op equency and on he dimensionless wa eleng h in ela ion o he Reynolds numbe was esea ched, as displayed in Figu e 4 o he lowe ( hi d) cylinde . The igh ho izon al axis s ands o he d op equency, i.e. how many d ops ha e sepa a ed om he middle cylinde pe second. The da a p esen ed in his Figu e ha e only been ob ained by measu ing and hey ha e no been compa ed wi h a nume ical model. The 0.1 m, 0.05 m and 0.02 m diame e s we e s udied and hey a e ma ked in he diag am legend as " eq. – exp. D = …". The measu ed alues demons a e a signi ican mode s abili y a e he Reynolds numbe alue 100 [-] has been eached. Howe e , he inc ease p eceding his alue has been ela i ely s eady despi e he ac ha i amoun s o app ox. 24% a 0.02 m diame e , app ox. 44% a he 0.05 m diame e and 38% a he la ges 0.1 m diame e . The au ho s do no s a e he span and su ace ype o cylinde s. Figu e 4 In luence o cylinde diame e on d op equency and dimensionless wa eleng h [4] The uppe hal o he Figu e 4 illus a es he dependences o he dimensionless wa eleng h on he Reynolds numbe o all h ee s udied diame e s. The esul s o he expe imen (ma ked in he legend as "exp. D = ...") and o he nume ical model (ma ked in he legend as "model D = ...") a e compa ed o each diame e . The au ho s ound ou ha he di e ence o esul s be ween he expe imen and he nume ical model go smalle wi h a dec easing diame e . The au ho s gi e he de ia ion anging be ween 1% and 2% a he smalles diame e , be ween 1.0% and 4.5% a he middle diame e and be ween 1.0% and 13.7% a he la ges diame e . The inal s abili y o he Reynolds numbe alue 100 [-] achie emen ha occu ed a hese bo de s as well as a he d op equency p o es no able, al hough he s abili y a his quan i y has been much mo e signi ican . 2.3 In luence o sp inkled ubes span The in luence o he gap be ween he sp inkled p o iles on he low mode ype was es ed by Wang e al. [8]. The bundle es ed comp ised o a dis ibu ion ube ou o which a liquid was lowing ( he subs ances es ed we e e hylene glycol and wa e ), a ube o ci cula c oss- sec ion he pu pose o which was o egula e he alling ilm liquid dis ibu ion and wo la ubes ha c ea ed EFM 2013 02060-p.3 a gap ha demons a ed he low mode. The la ubes es ed we e made o a polished aluminium o he dimensions 400 x 25.4 x 3.18 mm (leng h x heigh x wid h). The measu ing i sel was p eceded by a 2 o 3 hou ube sp inkling in o de o ensu e an ideal adhe ence o liquid o he su ace (so ha he su ace was ideally we able). The measu emen p ocedu e was ollowed o dec ease he low a e om he maximum and a e he ze o low a e had been eached, i was again inc eased o he maximum possible a e. The measu emen was epea ed h ee imes o each p o ile gap and only a e hese esul s we e ob ained he Reynolds numbe s o he gi en mode ansi ion and he ela i e e o o hese alues we e de e mined. Table 2 Reynolds numbe s o a ious ube pi ches acco ding o Wang e al. [8] a) Inc easing low s-D [mm] D ĺ D-J D-J ĺ J J ĺ J-S J-S ĺ S 4.8 203 259 363 395 6.4 231 293 390 427 9.5 230 298 430 459 14.5 244 320 435 473 19.4 262 336 434 481 24.5 268 348 448 512 RMS% 4.21 1.40 0.84 2.34 b) Dec easing low s-D [mm] S ĺ S-J S-J ĺ J J ĺ J-D J-D ĺ D 4.8 395 365 268 209 6.4 429 389 289 230 9.5 461 427 297 227 14.5 470 426 328 236 19.4 486 431 335 262 24.5 513 449 341 264 RMS% 0.87 0.77 1.53 4.53 Table 2 p o ides an o e iew o he measu emen esul s whe e wa e o app oxima ely he same physical p ope ies ha we e exp essed by he au ho s by means o he modi ied Galilei numbe Ga0.25 § 450 [-] was used as he alling ilm liquid. This alue a a mosphe ic p essu e (101 325 Pa) co esponds wi h he wa e empe a u e o app ox. 27.4 °C ( ound in [9]). To achie e he gi en measu emen esul s, he au ho s se he gap be ween he s abiliza ion ube and he i s p o ile o 2.0 mm. Thei esul s sugges ha he la ge he gap be ween he sp inkled p o iles, he highe he Reynolds numbe o he gi en sp inkle mode. This inc ease, howe e , did no p o e o be s eady, i.e. in one case o he gap inc ease he nex Reynolds numbe was e en lowe by app ox. 1.0% which does no seem o be a co ec alue as he inc easing gap causes he ho izon al sp inkled diame e o inc ease as well and he e o e mo e liquid, i.e. highe low a e, is necessa y a a la ge gap in o de o achie e he same sp inkle mode. When compa ing he Reynolds numbe s belonging o he smalles and he la ges gaps be ween he p o iles a indi idual modes he inc ease anges be ween app ox. 23% and 32%. The di e ence o he Reynolds numbe s be ween he inc easing and dec easing low a e a indi idual s a es equals on a e age 1.1% wi h a s anda d de ia ion o 1.1%. 2.4 Comp ehensi e de e mina ion o sp inkle mode a eas In he abo e men ioned s udy by Hu and Jacobi [3] he conclusion was eached on he basis o he measu emen ha nei he he diame e o sp inkled ubes no he gap be ween hem exe cises any signi ican in luence on a sp inkle mode. The es ed a io o he gap be ween ubes and he sp inkled ube diame e anged app ox. om 0.22 o 5.3 [-]. Fo he pu poses o p ac ical applica ion and compa ison wi h o he au ho s equa ions o indi idual modes we e c ea ed wi hou dis inguishing he inc ease o dec ease o he alling ilm liquid low a e, while he ela i e e o did no signi ican ly inc ease. Cons an s o indi idual equa ions de i ed om he equa ion (1) a e gi en in Table 3, i.e. hey a e displayed in Figu e 5 in he Reynolds numbe and he modi ied Galilei numbe ange 0 o 600 [-]. Figu e 5 Sp inkle modes bo de s acco ding o Hu and Jacobi [3] Figu e 5 also illus a es h ee Je mode ypes ha Hu and Jacobi speci ied. The i s one is a so called "in- line" Je mode ype. This mode ype occu s a low alling ilm liquid low a es and he liquid alls down in columns ha a e connec ed in on o he ube and behind i . I.e. hey c ea e a single ow and hey do no mo e e ically. The bo de o his mode is de e mined by he equa ion (2) ha does no dis inguish he inc ease EPJ Web o Con e ences 02060-p.4 o dec ease o he low a e and he ela i e e o o he equa ion is 12.5%. Re = 20.53 + 0.256·(Ga)0.25 (2) The o he wo phases o he Je mode a e s a es whe e in he i s case he columns pendula e e ically a ound an imagina y poin and in he second case he way columns mo e can no longe be p edic ed. The bo de be ween hese phases is de e mined o inc easing and dec easing alling ilm liquid low a e in he equa ion (3), whe e he ela i e e o o he equa ion is se a 8.3%. Re = 47.42 + 0.600·(Ga)0.25 (2) O he au ho s who deal wi h expe imen al di ision o sp inkle modes a e A mb us e and Mi o ic who published he esul s o hei esea ch o ins ance in [2]. Thei expe imen al de ice consis ed o a dis ibu ion essel o 260 mm leng h wi h ape u es o 1 mm diame e a 3 mm span a he bo om, a s abiliza ion ube o 18 mm diame e posi ioned di ec ly below he ape u es, a es ube (also o 18 mm diame e ) and a collec ion d ain. The liquid es ed was dis illed wa e in empe a u e ange om 15 o 55 °C. The mass low o wa e anged be ween 0.02 and 0.24 kg/(sÂm) and i was de e mined by a di e en ial me hod, i.e. by weighing he dis ibu ion essel bo h be o e and a e he pa icula mode es ing. F om he alues measu ed o indi idual bo de s he unc ional dependence was se acco ding o he equa ion (1) and he inal cons an s a e gi en in Table 3. Howe e , no ela i e e o is men ioned a hei equa ions. Table 3 Reynolds numbe s o a ious ube pi ches acco ding o Wang e al. [8] A mb us e and Mi o ic [2] Hu and Jacobi [3] Roques e al. [7] D – D-J A 0.200 0 0.074 (11.0 %) 0.041 7 B 0.250 0 0.302 0.327 8 D-J – J A 0.260 0 0.096 (11.2 %) 0.068 3 B 0.250 0 0.301 0.320 4 J – J-S A 0.920 0 1.414 (5.8 %) 0.855 3 B 0.250 0 0.233 0.248 3 J-S – S A 1.140 0 1.448 (6.6 %) 1.068 0 B 0.250 0 0.236 0.256 3 Table 3 also shows he esul s o Roques e al. [7]. In o de o de e mine sp inkle modes hey c ea ed an expe imen al de ice consis ing o a dis ibu ion essel wi h a la bo om o 260 x 10 mm and d illed ape u es o 1.0 mm diame e a 2.0 mm span along he leng h o 200 mm. The e we e h ee es ed coppe ubes o 19.04 mm posi ioned below he bo om ha ha e been sandblas ed be o e he es ing i sel and hus hollows o app ox. 0.3 ȝm o 2.0 ȝm we e o med a hei su ace. Figu e 6 Compa ison o sp inkle modes' bo de s by a ious au ho s Figu e 6 p esen s a compa ison o indi idual sp inkle modes' bo de s desc ibed by he abo e men ioned au ho s and he cons an s de e mined by hem gi en in Table 3 in o he equa ion (1). Values in he diag am a e displayed in a loga i hmic scale; i.e. he Reynolds numbe in he ange om 10 o 1 000 [-] and he modi ied Galilei numbe in he ange om 50 o 1 000 [-]. The diag am clea ly shows a ce ain co espondence o he end be ween he Je and he Shee mode, bu in he case o a ansi ion om he Je o he D ople mode i is no so e iden . The na owes ansi ion s ips a e in he case o Hu and Jacobi, which is 30% o 60% compa ed o A mb us e and Mi o ic, bu hei da a we e ob ained a a smalle expe imen al sample. 3 Expe imen al de ice Fo he pu pose o hea ans e a sp inkled ube bundles esea ch an expe imen al de ice has been cons uc ed consis ing o a cylinde essel o 1.2 m leng h wi h a ube bundle posi ioned inside. Vacuum is gene a ed in he chambe using an exhaus e ia ejec o . Tube bundle wi h a geome y isible in Figu e 7 consis s o coppe ubes o 12 mm ou e diame e . Two geome ically iden ical ube bundles di e en ia ed by a sp inkled ube su ace we e s udied. The i s bundle consis ed o smoo h ubes and he second one o sandblas ed ubes. The di e ence be ween he indi idual su ace ypes is isible in Figu e 8. EFM 2013 02060-p.5 Figu e 7 Simpli ied diag am o ube bundle Figu e 8 Sp inkled ube su ace ypes (smoo h one on he le and sandblas ed one on he igh ) Fu he de ails on he expe imen al de ice a e published o ins ance a [5, 6] including pa ial measu emen esul s. The calcula ion o he hea ans e coe icien in his pape is based on he he mal balance acco ding o he law o conse a ion o ene gy based on a simpli ied diag am in Figu e 7, he New on's law o hea ans e and he Fou ie 's law o hea conduc ion. 4 Measu emen esul s The expe imen s desc ibed in his pape in ol ed he hea ing o a alling ilm liquid. Tha means ha ho wa e o he a e age inpu empe a u e 55.2 °C and he a e age low a e 12.4 l·min was lowing inside smoo h ubes-1. The a e age alling ilm liquid empe a u e a he dis ibu ion ube ou le was 29.9 °C and he es ed alling ilm liquid low a e anged om 0 o 15.8 l·min-1. In case o sandblas ed ubes ho wa e o he a e age inpu empe a u e 55.1 °C and he a e age low a e 13.7 l·min-1 was lowing and he exchange was sp inkled by cold wa e o a e age empe a u e a he dis ibu ion ube ou le o 29.8 °C and he olume ic low a e anged be ween ze o and 16.1 l·min-1. Tes ed ange o an absolu e p essu e in he chambe anged in bo h cases om 12.3 kPa(a) o he a mosphe ic p essu e ha was a he ime o measu emen 96.8 kPa(a) on a e age. Figu e 9 Images o he mog aphic measu emen Figu e 8 shows images o he mog aphic measu emen eco ded by a he mog aphic came a FLIR SC 660 wi h he esolu ion o 640 x 480 pixels du ing he whole measu ing p ocess a smoo h and sandblas ed ubes. The scale o all images anges be ween 25 – 60 °C and he exchange g adien is he abo e men ioned 55 °C o 30 °C. The alling ilm liquid ou le om a dis ibu ion ube is isible a he uppe pa o he images. The i s image was cap u ed du ing he alling ilm liquid low a e 3.5 l·min-1 and i is a pu e D ople mode. The second image eco ds he low a e o 5.5 l·min-1 and due o a su icien amoun o liquid i s columns can be dis inguished. This bo de was app oxima ely he same in smoo h and sandblas ed ubes. The hi d and ou h image display he low a e 7.5 and 10.2 l·min-1, EPJ Web o Con e ences 02060-p.6 espec i ely. A g adual inc ease in he numbe o columns and a co esponding dec ease o d ops can be obse ed. In spi e o his ac he D ople mode domina es in he lowe pa o he bundle. The las image illus a es he low a e 12.4 l·min-1 ha is app oxima ely he op bo de o he D ople -Je mode. Figu e 10 Wa e o ms o empe a u e in exchange and o mean hea ans e coe icien a ube su ace in ela ion o alling ilm wa e low a e Figu e 10 depic s he cooling liquid empe a u e ( he liquid lowing inside he ubes) in ela ion o he alling ilm liquid low a e. The empe a u es we e measu ed a he beginning ( 5) and a he end o he bundle ( 6; he bundle's leng h is 12.22 m) and a e wa ds he empe a u es we e measu ed a 2.86 m ( 13) and 8.46 m ( 15; conside ed in he di ec ion opposi e o he cooling liquid low) du ing he sp inkling p ocess. Full cu es ep esen he smoo h- ube exchange and he dashed cu es illus a e he sandblas ed- ube exchange . The same image also displays he wa e o ms o he s udied ans e coe icien in smoo h and sandblas ed ubes wi h a ela i e e o 4.3% ±4.3 in smoo h ubes and 4.7% ±4.3 in sandblas ed ubes. These wa e o ms we e de e mined om he o al numbe o 4 487 measu ed poin s. 5 Conclusions The pape 's objec i e was o b ie ly desc ibe basic po en ial he modynamic in e connec ions om he pe spec i e o alling ilm liquid and basic physical pa ame e s ha exe cise hei in luence on a sp inkle mode. The e a e a ious s udies dealing wi h he basic sp inkle modes' phases and hei ansi ions, howe e , no gene al consensus has been eached as o which pa ame e s ha e a p ac ical in luence on a sp inkle mode. The esea ch conduc ed a he B no Uni e si y o Technology, Ene gy Ins i u e, dep . o Powe Enginee ing aims o delinea e hese mechanisms. This pape p esen s he esul s ha ha e been s udied a wo geome ically iden ical exchange s di e en ia ed by a su ace ype; in pa icula a smoo h one and a sandblas ed one. Due o he ube bundle size and he alling ilm liquid olume ic low a e only he Je mode (S agge ed) has been eached a maximum low a e. Based on a isual obse a ion, he ansi ions co esponding bes we e hose de ined by A mb us e and Mi o ic (1994). In ou case, howe e , he e is a eal bundle, no only h ee ubes posi ioned ho izon ally one below each o he . The empe a u e in his bundle a ies acco ding o he heigh and he e o e indi idual modes occu successi ely and i is di icul o de e mine one speci ic mode di ec ly. The main esul s o ou esea ch ac i i y a e p esen ed in Figu e 10. This Figu e shows ou empe a u es measu ed inside he exchange . As he empe a u e change clea ly sugges s, he e is a smalle he mal g adien in sandblas ed ubes in compa ison o smoo h ones a low low a es and consequen ly his pa also p o es a lowe hea ans e coe icien a ube su ace. A possible eason o his can be an incomple e wa e w apping o he sandblas ed ube su ace due o i s oughness. Howe e , he low a e inc ease makes his di e ence diminish. This can be caused by an al eady exis ing complex s abilized wa e ilm ha he main s eam slides along and ha is hicke han in smoo h ube. Ou u he esea ch will ocus on o he ypes o ube su aces and hei in luence on he hea ans e coe icien and a ious admix u es bo h soluble and insoluble in wa e which a ec he su ace ension a dec easing p essu e and we would like o iden i y he ad an age o low p essu e inside a chambe as he hea ans e coe icien eac s di e en ly wi h some low a es a ube bundle han a coe icien measu ed a one, wo o h ee ubes placed ho izon ally one abo e he o he . Acknowledgemen This pape was c ea ed wi h he inancial suppo o he Czech Science Founda ion wi hin he P101/10/1669 g an and he NETME Cen e p ojec unded by he Ope a ional P og amme Resea ch and De elopmen o Inno a ions ha is co- unded by ERDF (Eu opean Regional De elopmen Fund). EFM 2013 02060-p.7 Re e ences 1. A mb us e , R. J. Mi o ic, Expe imen al The mal and Fluid Science 18 (3), 183 (1998) 2. A mb us e , R. J. Mi o ic, P oceedings o he 10 h in e na ional hea ans e con e ence 3, 275 (1994) 3. Hu, X. A. M. Jacobi, Jou nal o Hea T ans e 118 (3), 616 (1996) 4. Ja a , Tho pe and Tu an, Compu a ional luid dynamics se en h in e na ional con e ence on CFD in he mine als and p ocess indus ies. (2009) 5. P. K acík, J. Pospíšil, L. Šnajdá ek, Ac a Poly echnica 52 (3), 48 (2012) 6. P. K acík, L. Šnajdá ek, J. Pospíšil, EPJ Web o Con e ences 45 (01052), (2013) 7. J.F. Roques, V. Dupon and J. R. Thome. Jou nal o Hea T ans e [online] 124 (3), 491 (2002) 8. X. Wang, P. S. H njak, S. Elbel, A. M. Jacobi and M. He, Jou nal o Hea T ans e 124 (2), 1 (2012) 8. X-ENG. X S eam Tables o MS Excel [poþí aþo ý soubo .xls]. Ve . 2.6. [online]. [ci . 30.11.2010]. F eewa e. <h p://www.x- eng.com/XS eam_Excel.h m>. Nomencla u e A, B [-] cons an s in he equa in (1) Į [WÂm-2ÂK-1] hea ans e coe icien D [m] diame e D d ople mode D-J d ople – je mode exp. expe imen eq. equncy Ga [-] Galileo numbe J je mode J-D je – d ople mode J-S je – shee mode p [Pa] p essu e Re [-] Reynolds numbe S shee mode S-J shee – je mode [°C] empe a u e V [m3Âs-1] olume ic low Subsc ip s 1 condi ion o alling ilm liquid in dis ibu ion ube 2 condi ion o alling ilm liquid a essel bo om 5 condi ion o he cooling/hea ing liquid a loop inpu 6 condi ion o he cooling/hea ing liquid a loop ou pu o condi ion ou side he ube V acuum loop EPJ Web o Con e ences 02060-p.8