304 chitsulo chosapanga dzimbiri chophimbidwa ndi chigawo cha mankhwala, Thermodynamic kusanthula kwa covalently and non-covalently functionalized graphene nanosheets mu machubu ozungulira okhala ndi turbulators

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304 10 * 1mm Chitsulo chosapanga dzimbiri chophimbidwa ndi machubu ku China

Kukula: 3/4 inchi, 1/2 inchi, 1 inchi, 3 inchi, 2 inchi

Utali wa Chitoliro cha Unit: 6 mita

Gulu la Zitsulo: 201, 304 NDI 316

Gulu: 201, 202, 304, 316, 304L, 316 L,

Zida: STAINLESS zitsulo

Mkhalidwe: Watsopano

Covalent and non-covalent nanofluids adayesedwa mu machubu ozungulira okhala ndi zopindika za tepi zokhala ndi ma helix angles a 45 ° ndi 90 °.Nambala ya Reynolds inali 7000 ≤ Re ≤ 17000, katundu wa thermophysical adayesedwa pa 308 K. Chitsanzo cha thupi chimathetsedwa mwachiwerengero pogwiritsa ntchito chitsanzo cha chipwirikiti chachiwiri (SST k-omega turbulence).Zomwe zili (0.025 wt.%, 0.05 wt.%, ndi 0.1 wt.%) za nanofluids ZNP-SDBS@DV ndi ZNP-COOH@DV zinaganiziridwa pa ntchitoyi.Makoma a machubu opotoka amatenthedwa ndi kutentha kosalekeza kwa 330 K. Magawo asanu ndi limodzi adaganiziridwa mu phunziro lamakono: kutentha kwa kutuluka, kutentha kwa kutentha, chiwerengero cha Nusselt, chiwerengero cha mikangano, kutayika kwa mphamvu, ndi njira zowunikira ntchito.Pazochitika zonsezi (makona a helix a 45 ° ndi 90 °), ZNP-SDBS@DV nanofluid inasonyeza makhalidwe apamwamba a kutentha-hydraulic kuposa ZNP-COOH@DV, ndipo inawonjezeka ndi kuchuluka kwa magawo, mwachitsanzo, 0.025 wt.ndi 0.05wt.ndi 1.19.% ndi 1.26 - 0.1 wt.%.Muzochitika zonsezi (makona a helix 45 ° ndi 90 °), makhalidwe a thermodynamic mukamagwiritsa ntchito GNP-COOH@DW ndi 1.02 kwa 0.025% wt., 1.05 kwa 0.05% wt.ndi 1.02 kwa 0.1% wt.
Chojambulira kutentha ndi chipangizo cha thermodynamic 1 chomwe chimagwiritsidwa ntchito kusamutsa kutentha pakuzizira ndi kutentha.Thermal-hydraulic properties of the heat exchanger imapangitsanso kutentha kwapakati komanso kuchepetsa kukana kwa madzi ogwira ntchito.Njira zingapo zapangidwa kuti zithandizire kusintha kutentha, kuphatikizapo turbulence enhancers2,3,4,5,6,7,8,9,10,11 ndi nanofluids12,13,14,15.Kuyika tepi yokhotakhota ndi imodzi mwa njira zopambana kwambiri zowonjezeretsa kutentha kwa kutentha muzitsulo zotentha chifukwa chosavuta kukonza komanso kutsika mtengo7,16.
M'maphunziro angapo oyesera komanso owerengera, mphamvu za hydrothermal zosakaniza za nanofluids ndi zotenthetsera zokhala ndi zopindika za tepi zidaphunziridwa.Mu ntchito yoyesera, mphamvu za hydrothermal za nanofluids zitsulo zitatu zosiyana (Ag@DW, Fe@DW ndi Cu@DW) zinaphunziridwa mu tepi yopotoka ya singano (STT) kutentha kutentha17.Poyerekeza ndi chitoliro choyambira, kutentha kwa kutentha kwa STT kumapangidwa bwino ndi 11% ndi 67%.Maonekedwe a SST ndi abwino kwambiri pazachuma pakuwona bwino ndi gawo α = β = 0.33.Kuonjezera apo, kuwonjezeka kwa 18.2% mu n kunkawoneka ndi Ag @ DW, ngakhale kuti kuwonjezeka kwakukulu kwa kutaya mphamvu kunali 8.5% yokha.Njira zakuthupi za kusamutsa kutentha ndi kutayika kwamphamvu m'mapaipi okhazikika okhala ndi ma turbulators opindika komanso opanda zida zidaphunziridwa pogwiritsa ntchito chipwirikiti cha Al2O3@DW nanofluid chokakamiza.Chiwerengero chapamwamba cha Nusselt (Nuavg) ndi kutayika kwa mphamvu kumawonedwa pa Re = 20,000 pamene koyilo phula = 25 mm ndi Al2O3@DW nanofluid 1.6 vol.%.Kafukufuku wa labotale adachitikanso kuti aphunzire kutengera kutentha komanso kutayika kwamphamvu kwa ma graphene oxide nanofluids (GO@DW) omwe amadutsa pafupifupi machubu ozungulira okhala ndi ma WC.Zotsatira zake zidawonetsa kuti 0.12 vol% -GO@DW idachulukitsa kutentha kwapakati ndi 77%.Mu kafukufuku wina woyesera, ma nanofluids (TiO2@DW) adapangidwa kuti aphunzire mawonekedwe amafuta-hydraulic a machubu a dimpled ophatikizidwa ndi zopindika za tepi zoyika20.Kugwiritsa ntchito bwino kwambiri kwa hydrothermal kwa 1.258 kunapezedwa pogwiritsa ntchito 0.15 vol% -TiO2 @ DW yophatikizidwa muzitsulo za 45 ° zokhotakhota ndi zopotoka za 3.0.Zitsanzo zofananira za gawo limodzi ndi magawo awiri (wosakanizidwa) zimaganizira za kuyenda ndi kutentha kwa CuO@DW nanofluids pamagulu osiyanasiyana olimba (1-4% vol.%)21.Kutentha kwapamwamba kwa chubu yomwe imayikidwa ndi tepi imodzi yokhotakhota ndi 2.18, ndipo chubu chomwe chimayikidwa ndi matepi awiri opotoka pansi pamikhalidwe yomweyi ndi 2.04 (chitsanzo cha magawo awiri, Re = 36,000 ndi 4 vol.%).Kutuluka kwa chipwirikiti kwa nanofluid kosakhala kwa Newtonian kwa carboxymethyl cellulose (CMC) ndi copper oxide (CuO) m'mapaipi akulu ndi mapaipi okhala ndi zopindika zaphunziridwa.Nuavg ikuwonetsa kusintha kwa 16.1% (kwa payipi yayikulu) ndi 60% (kwa mapaipi opindika okhala ndi chiŵerengero cha (H/D = 5)).Nthawi zambiri, chiŵerengero chochepa cha twist-to-riboni chimapangitsa kuti phokoso likhale lokwera kwambiri.Mu kafukufuku woyesera, zotsatira za mipope yokhala ndi tepi yopotoka (TT) ndi ma coils (VC) pa katundu wa kutentha kwa kutentha ndi friction coefficient anaphunzira pogwiritsa ntchito CuO@DW nanofluids.Kugwiritsa ntchito 0.3 vol.% -CuO @ DW pa Re = 20,000 zimapangitsa kuti ziwonjezeke kutentha kwa VK-2 chitoliro mpaka 44,45%.Kuphatikiza apo, mukamagwiritsa ntchito chingwe chopotoka ndikuyika koyilo pansi pamalire omwewo, kugundana kumawonjezeka ndi zinthu za 1.17 ndi 1.19 poyerekeza ndi DW.Nthawi zambiri, kutentha kwamphamvu kwa ma nanofluids omwe amalowetsedwa m'makoyilo ndikwabwino kuposa ma nanofluids omwe amalowetsedwa mu mawaya otsekeka.Mawonekedwe a volumetric wa chipwirikiti (MWCNT@DW) nanofluid flow adaphunziridwa mkati mwa chubu chopingasa choyikidwa mu waya wozungulira.The matenthedwe ntchito magawo anali> 1 pazochitika zonse, kusonyeza kuti kuphatikiza nanofluidics ndi koyilo Ikani bwino kutentha kutentha popanda kuwononga mpope mphamvu.Chidule-Makhalidwe a hydrothermal a chotenthetsera cha mipope iwiri yokhala ndi zoyika zosiyanasiyana zopangidwa ndi tepi yopindika yopindika yooneka ngati V (VcTT) aphunziridwa pansi pakuyenda kwa chipwirikiti kwa Al2O3 + TiO2@DW nanofluid.Poyerekeza ndi DW m'machubu oyambira, Nuavg ili ndi kusintha kwakukulu kwa 132% komanso kugunda kwapakati mpaka 55%.Kuphatikiza apo, kugwiritsa ntchito mphamvu kwa Al2O3 + TiO2 @ DW nanocomposite mu chowotcha chotenthetsera cha mipope iwiri26 chinakambidwa.Mu kafukufuku wawo, adapeza kuti kugwiritsa ntchito Al2O3 + TiO2@DW ndi TT kumapangitsa kuti ntchito ziziyenda bwino poyerekeza ndi DW.Mu concentric tubular kutentha exchanger ndi VcTT turbulators, Singh ndi Sarkar27 ntchito gawo kusintha zipangizo (PCM), omwazikana single/nanocomposite nanofluids (Al2O3@DW ndi PCM ndi Al2O3 + PCM).Iwo adanenanso kuti kusuntha kwa kutentha ndi kuchepa kwa kuthamanga kumawonjezeka pamene kupotoza kokwanira kumachepa ndipo ndende ya nanoparticle ikuwonjezeka.Chinthu chokulirapo cha V-notch kapena chocheperako chocheperako chingapereke kutentha kwakukulu komanso kutaya mphamvu.Kuphatikiza apo, graphene-platinum (Gr-Pt) yakhala ikugwiritsidwa ntchito pofufuza kutentha, kukangana, ndi kuchuluka kwa kuchuluka kwa entropy m'machubu okhala ndi 2-TT28.Kafukufuku wawo adawonetsa kuti gawo laling'ono la (Gr-Pt) limachepetsa kwambiri m'badwo wa kutentha kwa entropy poyerekeza ndi chitukuko chokwera kwambiri cha entropy.Osakaniza Al2O3 @ MgO nanofluids ndi conical WC akhoza kuonedwa ngati osakaniza bwino, popeza chiŵerengero chowonjezeka (h / Δp) chikhoza kupititsa patsogolo ntchito ya hydrothermal ya 29 chubu yotentha kutentha.Mtundu wa manambala umagwiritsidwa ntchito poyesa kupulumutsa mphamvu ndi momwe chilengedwe chimagwirira ntchito zosinthira kutentha zokhala ndi magawo atatu osiyanasiyana osakanizidwa a nanofluids (THNF) (Al2O3 + graphene + MWCNT) oimitsidwa mu DW30.Chifukwa cha Zomwe Zimagwira Ntchito (PEC) mu 1.42-2.35, kuphatikiza kwa Depressed Twisted Turbulizer Insert (DTTI) ndi (Al2O3 + Graphene + MWCNT) kumafunika.
Mpaka pano, chidwi chochepa chaperekedwa ku gawo la covalent ndi non-covalent functionalization mu hydrodynamic otaya madzi matenthedwe.Cholinga chenicheni cha phunziroli chinali kufanizitsa makhalidwe a kutentha-hydraulic a nanofluids (ZNP-SDBS@DV) ndi (ZNP-COOH@DV) muzitsulo zopotoka za tepi ndi helix angles za 45 ° ndi 90 °.Thermophysical katundu anayesedwa pa Tin = 308 K. Pankhaniyi, zigawo zitatu zazikuluzikulu zimaganiziridwa poyerekezera, monga (0.025 wt.%, 0.05 wt.% ndi 0.1 wt.%).Kusuntha kwa kumeta ubweya wa ubweya mu 3D turbulent flow model (SST k-ω) imagwiritsidwa ntchito kuthetsa zizindikiro za kutentha-hydraulic.Chifukwa chake, phunziroli limathandizira kwambiri pakuwunika kwazinthu zabwino (kutengera kutentha) ndi zinthu zoyipa (kutsika kwapakati pa kukangana), kuwonetsa mawonekedwe amafuta-hydraulic ndi kukhathamiritsa kwamadzi enieni ogwira ntchito m'makina oterowo.
Kukonzekera koyambira ndi chitoliro chosalala (L = 900 mm ndi Dh = 20 mm).Miyezo ya tepi yopotoka (kutalika = 20 mm, makulidwe = 0.5 mm, mbiri = 30 mm).Pankhaniyi, kutalika, m'lifupi, ndi sitiroko za ozungulira mbiri anali 20 mm, 0.5 mm, ndi 30 mm, motero.Matepi opotoka amakhoterera pa 45 ° ndi 90 °.Zamadzimadzi osiyanasiyana ogwira ntchito monga DW, non-covalent nanofluids (GNF-SDBS@DW) ndi covalent nanofluids (GNF-COOH@DW) pa Tin = 308 K, magulu atatu osiyana siyana ndi manambala a Reynolds osiyanasiyana.Mayeserowo anachitidwa mkati mwa chotenthetsera kutentha.Khoma lakunja la chubu la spiral lidatenthedwa pamtunda wokhazikika wa 330 K kuyesa magawo owongolera kutentha.
Pa mkuyu.1 ikuwonetsa mwadongosolo chubu choyika tepi chopotoka chokhala ndi malire oyenera komanso malo olumikizirana.Monga tanenera kale, kuthamanga ndi malire a malire akugwira ntchito kumalo olowera ndi kutuluka kwa helix.Pa kutentha kosalekeza pamwamba, chikhalidwe chosasunthika chimayikidwa pa khoma la chitoliro.Kuyerekezera kwamakono kwa chiwerengero kumagwiritsa ntchito njira yothetsera mavuto.Panthawi imodzimodziyo, pulogalamu (ANSYS FLUENT 2020R1) imagwiritsidwa ntchito kutembenuza a partial differential equation (PDE) kukhala dongosolo la algebraic equations pogwiritsa ntchito njira yomaliza ya voliyumu (FMM).Njira yachiwiri ya SIMPLE (njira yokhazikika yotsatizana yotsatizana ndi kukakamiza) imagwirizana ndi kuthamanga kwa liwiro.Tiyenera kutsindika kuti kuphatikizika kwa zotsalira za misa, mphamvu, ndi mphamvu ndizochepera 103 ndi 106, motsatana.
p Chithunzi cha madera akuthupi ndi owerengera: (a) ngodya ya helix 90 °, (b) ngodya ya helix 45 °, (c) palibe tsamba la helical.
A homogeneous chitsanzo ntchito kufotokoza katundu wa nanofluids.Pophatikiza ma nanomatadium m'madzimadzi oyambira (DW), madzimadzi osalekeza okhala ndi zinthu zabwino kwambiri zamatenthedwe amapangidwa.Pankhani imeneyi, kutentha ndi liwiro la madzimadzi m'munsi ndi nanomaterial ali ndi mtengo womwewo.Chifukwa cha malingaliro ndi malingaliro omwe ali pamwambawa, kuyenda bwino kwa gawo limodzi kumagwira ntchito mu phunziroli.Maphunziro angapo awonetsa mphamvu komanso kugwiritsa ntchito njira zagawo limodzi za nanofluidic flow31,32.
Kuthamanga kwa nanofluids kuyenera kukhala kwa Newtonian chipwirikiti, kosasunthika komanso kosasunthika.Ntchito yopondereza ndi kutentha kwa viscous ndizosafunikira mu kafukufukuyu.Kuonjezera apo, makulidwe a makoma amkati ndi akunja a chitoliro samaganiziridwa.Chifukwa chake, kuchuluka, mphamvu, ndi kusungitsa mphamvu zomwe zimatanthawuza mtundu wamafuta zitha kuwonetsedwa motere:
kumene \(\ overrightarrow{V}\) ndi velocity vector, Keff = K + Kt ndiye mphamvu yotentha ya nanofluids ya covalent ndi noncovalent, ndipo ε ndiye mphamvu yotaya mphamvu.Thermophysical katundu wa nanofluids, kuphatikizapo kachulukidwe (ρ), mamasukidwe akayendedwe (μ), enieni kutentha mphamvu (Cp) ndi matenthedwe conductivity (k), zosonyezedwa pa tebulo, anayeza pa kafukufuku kuyesera pa kutentha kwa 308 K1 pamene ntchito. mu simulators izi.
Mawerengero amtundu wa chipwirikiti othamanga a nanofluid m'machubu ochiritsira ndi a TT anachitidwa pa nambala za Reynolds 7000 ≤ Re ≤ 17000. Zofananirazi ndi ma convective kutentha kutentha kwapakati kunayesedwa pogwiritsa ntchito chitsanzo cha Mentor's κ-ω chipwirikiti cha shear average stress transfer (Sturynold) chitsanzo cha Navier-Stokes, chomwe chimagwiritsidwa ntchito kwambiri pa kafukufuku wa aerodynamic.Kuonjezera apo, chitsanzocho chimagwira ntchito popanda khoma ndipo chiri cholondola pafupi ndi makoma 35,36.(SST) κ-ω olamulira ma equation amtundu wa chipwirikiti ndi awa:
kumene \ (S \) ndi mtengo wa strain rate, ndipo \ (y\) ndi mtunda wopita kumalo oyandikana nawo.Pakadali pano, \({\alpha}_{1}\), \({\alpha}_{2}\), \({\beta}_{1}\), \({\beta}_{ 2 }\), \({\beta}^{*}\), \({\sigma}_{{k}_{1}}\), \({\sigma}_{{k}_{ 2 }}\), \({\sigma}_{{\omega}_{1}}\) ndi \({\sigma}_{{{\omega}_{2}}\) amaimira zitsanzo zonse.F1 ndi F2 ndi ntchito zosakanikirana.Chidziwitso: F1 = 1 m'malire wosanjikiza, 0 mukuyenda komwe kukubwera.
Magawo owunikira magwiridwe antchito amagwiritsidwa ntchito pophunzira kusamutsa kwa kutentha kwapang'onopang'ono, kokhazikika komanso kosagwirizana ndi kayendedwe ka nanofluid, mwachitsanzo31:
M'nkhaniyi, (\(\ rho\)), (\(v\)), (\({D}_{h}\))) ndi (\(\mu\)) amagwiritsidwa ntchito pa kachulukidwe, kuthamanga kwamadzi. , hydraulic diameter ndi viscosity yamphamvu.(\({C}_{p}\, \mathrm{u}\, k\)) - mphamvu yeniyeni ya kutentha ndi matenthedwe amadzimadzi oyenda.Komanso, (\(\dot{m}\)) imatanthawuza kuyenda kwa anthu ambiri, ndipo (\({T}_{out}-{T}_{in}\)) imatanthawuza kusiyana kwa kutentha kwa polowetsa ndi kutuluka.(NFs) amatanthauza covalent, non-covalent nanofluids, ndipo (DW) amatanthauza madzi osungunuka (base fluid).\({A}_{s} = \pi DL\), \({\ overline{T}}_{f}=\frac{\left({T}_{kunja}-{T}_{mu }\ kumanja)}{2}\) ndi \({\ overline{T}_{w}=\sum \frac{{T}_{w}}{n}\).
Thermophysical properties of the base fluid (DW), non-covalent nanofluid (GNF-SDBS@DW), ndi covalent nanofluid (GNF-COOH@DW) adatengedwa kuchokera m'mabuku ofalitsidwa (kafukufuku woyesera), Sn = 308 K, monga zomwe zikuwonetsedwa mu Table 134. M'njira yofananira Pakuyesa kupeza nanofluid yopanda covalent (GNP-SDBS@DW) yokhala ndi maperesenti odziwika, ma gramu ena a GNPs oyambirira adayesedwa poyambira pa digito.Kulemera kwa chiŵerengero cha SDBS/GNP yachibadwa ndi (0.5:1) yolemera mu DW.Pankhaniyi, covalent (COOH-GNP@DW) nanofluids anali apanga powonjezera carboxyl magulu padziko GNP ntchito kwambiri acidic sing'anga ndi voliyumu chiŵerengero (1: 3) wa HNO3 ndi H2SO4.Covalent ndi non-covalent nanofluids anaimitsidwa mu DW pa magawo atatu osiyana kulemera monga 0.025 wt%, 0.05 wt%.ndi 0.1% ya misa.
Mayeso odziyimira pawokha a ma mesh adachitika m'magawo anayi osiyanasiyana kuti awonetsetse kuti kukula kwa mauna sikukhudza kuyerekezera.Pankhani ya 45 ° torsion pipe, chiwerengero cha mayunitsi ndi kukula kwa 1.75 mm ndi 249,033, chiwerengero cha mayunitsi ndi kukula kwa 2 mm ndi 307,969, chiwerengero cha mayunitsi ndi kukula kwa 2.25 mm ndi 421,406, ndi chiwerengero cha mayunitsi. ndi kukula kwa unit 2 .5 mm 564 940 motsatira.Kuonjezera apo, mu chitsanzo cha chitoliro chopotoka cha 90 °, chiwerengero cha zinthu zomwe zili ndi 1.75 mm kukula kwake ndi 245,531, chiwerengero cha zinthu zomwe zili ndi 2 mm kukula kwake ndi 311,584, chiwerengero cha zinthu zomwe zili ndi 2.25 mm kukula kwake ndi 422,708, ndipo chiwerengero cha zinthu zomwe zili ndi kukula kwa 2.5 mm ndi 573,826.Kulondola kwa kuwerengera kwa katundu wamafuta monga (Tout, htc, ndi Nuavg) kumawonjezeka pamene kuchuluka kwa zinthu kumachepa.Panthawi imodzimodziyo, kulondola kwa mfundo za friction coefficient ndi kutsika kwapansi kunawonetsa khalidwe losiyana kwambiri (mkuyu 2).Gridi (2) idagwiritsidwa ntchito ngati gawo lalikulu la gululi kuti liwunikire momwe matenthedwe amadzimadzi amapangidwira muzochitika zofananira.
Kuyesa kusuntha kwa kutentha ndi kutsika kwamphamvu mopanda mauna pogwiritsa ntchito machubu a DW opindika pa 45° ndi 90°.
Zotsatira zamanambala zomwe zilipo zatsimikiziridwa kuti zimagwira ntchito potengera kutentha komanso kugundana kwamphamvu pogwiritsa ntchito kulumikizana kodziwika bwino ndi ma equation monga Dittus-Belter, Petukhov, Gnelinsky, Notter-Rouse ndi Blasius.Kuyerekeza kunachitika pansi pa chikhalidwe 7000≤Re≤17000.Malinga ndi mkuyu.3, pafupifupi ndi pazipita zolakwa pakati kayeseleledwe zotsatira ndi kutentha kutengerapo equation ndi 4.050 ndi 5.490% (Dittus-Belter), 9.736 ndi 11.33% (Petukhov), 4.007 ndi 7.483% (Gnelinsky), ndi 3.883% ndi 4. Nott-Belter).Rose).Pankhaniyi, zolakwa pafupifupi ndi pazipita pakati kayeseleledwe zotsatira ndi mikangano coefficient equation ndi 7.346% ndi 8.039% (Blasius) ndi 8.117% ndi 9.002% (Petukhov), motero.
Kusintha kwa kutentha ndi mphamvu za hydrodynamic za DW pamanambala osiyanasiyana a Reynolds pogwiritsa ntchito kuwerengera manambala ndi kulumikizana kwamphamvu.
Gawoli likufotokoza za kutentha kwa non-covalent (LNP-SDBS) ndi covalent (LNP-COOH) amadzimadzi nanofluids pamagulu atatu osiyana siyana ndi ma Reynolds manambala monga mavareji okhudzana ndi madzimadzi apansi (DW).Ma geometri awiri azitsulo zophimbidwa ndi lamba (makona a helix 45 ° ndi 90 °) amakambidwa kwa 7000 ≤ Re ≤ 17000. Mu mkuyu.4 ikuwonetsa kutentha kwapakati pakutuluka kwa nanofluid kulowa m'madzi oyambira (DW) (\(\frac{{{T}_{out}}_{NFs}}{{T}_{out}}_{ DW } } \) ) pa (0.025% wt., 0.05% wt. ndi 0.1% wt.).(\(\frac{{{T}_{out}}_{NFs}}{{{T}_{out}}_{DW}}\)) nthawi zonse imakhala yochepera 1, kutanthauza kuti kutentha kwa potuluka si covalent (VNP-SDBS) ndi covalent (VNP-COOH) nanofluids ndi m'munsimu kutentha pa kubwereketsa madzi m'munsi.Zotsika kwambiri komanso zotsika kwambiri zinali 0.1 wt%-COOH@GNPs ndi 0.1 wt%-SDBS@GNPs, motsatana.Chodabwitsa ichi ndi chifukwa cha kuchuluka kwa chiwerengero cha Reynolds pa gawo lokhazikika la misa, zomwe zimabweretsa kusintha kwa zinthu za nanofluid (ndiko kuti, kachulukidwe ndi kukhuthala kwamphamvu).
Zithunzi 5 ndi 6 zikuwonetsa kutentha kwapakati kwa nanofluid to base fluid (DW) pa (0.025 wt.%, 0.05 wt.% ndi 0.1 wt.%).Zomwe zimatengera kutentha kwapakati nthawi zonse zimakhala zazikulu kuposa 1, zomwe zikutanthauza kuti kutentha kwa kutentha kwa non-covalent (LNP-SDBS) ndi covalent (LNP-COOH) nanofluids kumawonjezeka poyerekeza ndi madzi oyambira.0.1 wt%-COOH@GNPs ndi 0.1 wt%-SDBS@GNPs adapeza phindu lotsika komanso lapamwamba kwambiri, motsatana.Chiwerengero cha Reynolds chikachulukirachulukira chifukwa cha kusakanikirana kwakukulu kwamadzimadzi komanso chipwirikiti mu chitoliro 1, kusintha kwa kutentha kumakhala bwino.Madzi omwe amadutsa m'mipata yaing'ono amafika pamtunda wokwera kwambiri, zomwe zimapangitsa kuti pakhale kucheperapo kwa liwiro / kutentha kumalire, zomwe zimawonjezera kutentha kwa kutentha.Kuonjezera ma nanoparticles kumadzimadzi oyambira kumatha kukhala ndi zotsatira zabwino komanso zoyipa.Zopindulitsa zimaphatikizapo kuchuluka kwa nanoparticle kugundana, zabwino zamadzimadzi matenthedwe madutsidwe zofunika, ndi kumatheka kutentha kutengerapo.
Kutengera kutentha kwa nanofluid kupita kumadzi oyambira kutengera nambala ya Reynolds ya machubu a 45° ndi 90°.
Pa nthawi yomweyo, zotsatira zoipa ndi kuwonjezeka kwamphamvu mamasukidwe akayendedwe a nanofluid, amene amachepetsa kuyenda wa nanofluid, potero kuchepetsa pafupifupi Nusselt chiwerengero (Nuavg).Kuwonjezeka kwa kutentha kwa nanofluids (ZNP-SDBS@DW) ndi (ZNP-COOH@DW) kuyenera kukhala chifukwa cha kayendedwe ka Brownian ndi microconvection ya graphene nanoparticles yomwe inaimitsidwa mu DW37.Thermal conductivity ya nanofluid (ZNP-COOH@DV) ndi yapamwamba kuposa ya nanofluid (ZNP-SDBS@DV) ndi madzi osungunuka.Kuwonjezera ma nanomatadium kumadzi oyambira kumawonjezera matenthedwe awo (Table 1)38.
Chithunzi cha 7 chikuwonetsa kuchuluka kwa mikangano ya nanofluids yokhala ndi madzi oyambira (DW) (f(NFs)/f(DW)) mu misa peresenti (0.025%, 0.05% ndi 0.1%).Avereji ya friction coefficient nthawi zonse imakhala ≈1, kutanthauza kuti non-covalent (GNF-SDBS@DW) ndi covalent (GNF-COOH@DW) nanofluids ali ndi friction coefficient yofanana ndi madzi oyambira.Chojambulira kutentha chokhala ndi malo ochepa chimapangitsa kuti madzi azitsekeka kwambiri ndikuwonjezera kukangana1.Kwenikweni, coefficient of friction imawonjezeka pang'ono ndikuwonjezeka kagawo kakang'ono ka nanofluid.Kuwonongeka kwakukulu kwamtunduwu kumayambitsidwa ndi kuchulukira kwamphamvu kwamphamvu kwa nanofluid komanso kumeta ubweya wambiri pamtunda ndi kuchuluka kwa nanographene m'madzi am'munsi.Table (1) imasonyeza kuti kukhuthala kwa viscosity ya nanofluid (ZNP-SDBS@DV) ndipamwamba kuposa ya nanofluid (ZNP-COOH@DV) pamlingo wolemera womwewo, womwe umagwirizanitsidwa ndi kuwonjezera kwa zotsatira za pamwamba.yogwira ntchito pa non-covalent nanofluid.
Pa mkuyu.8 ikuwonetsa nanofluid poyerekeza ndi madzimadzi oyambira (DW) (\(\frac{{\Delta P}_{NFs}}{{\Delta P}_{DW}}\)) pa (0.025%, 0.05% ndi 0.1% ).The non-covalent (GNPs-SDBS@DW) nanofluid anasonyeza apamwamba avareji kuthamanga kutaya, ndi kuwonjezeka misa peresenti kwa 2.04% kwa 0.025% wt., 2.46% kwa 0.05% wt.ndi 3.44% kwa 0.1% wt.ndi kukulitsa kwamilandu (makona a helix 45 ° ndi 90 °).Panthawiyi, nanofluid (GNPs-COOH@DW) inawonetsa kuchepa kwapakati, kuwonjezeka kuchokera ku 1.31% pa 0.025% wt.mpaka 1.65% pa 0.05% wt.Kutaya kwapakati pa 0.05 wt.% -COOH@NP ndi 0.1 wt.% -COOH@NP ndi 1.65%.Monga momwe tikuonera, kutsika kwamphamvu kumawonjezeka ndikuwonjezeka kwa Re number nthawi zonse.Kutsika kwamphamvu kwamphamvu pamitengo yayikulu ya Re kumawonetsedwa ndikudalira mwachindunji kuthamanga kwa voliyumu.Choncho, chiwerengero chapamwamba cha Re mu chubu chimayambitsa kutsika kwakukulu, zomwe zimafuna kuwonjezeka kwa mphamvu ya mpope39,40.Kuphatikiza apo, kutayika kwamphamvu kumakhala kokulirapo chifukwa cha kuchuluka kwamphamvu kwa ma eddy ndi chipwirikiti chomwe chimapangidwa ndi malo okulirapo, omwe amawonjezera kuyanjana kwamphamvu ndi mphamvu za inertia pagawo la malire1.
Nthawi zambiri, njira zowunikira magwiridwe antchito (PEC) za non-covalent (VNP-SDBS@DW) ndi covalent (VNP-COOH@DW) nanofluids zikuwonetsedwa mu Mkuyu.9. Nanofluid (ZNP-SDBS@DV) inawonetsa ma PEC apamwamba kuposa (ZNP-COOH@DV) m'zochitika zonse ziwiri (makona a helix 45 ° ndi 90 °) ndipo adawongoleredwa powonjezera gawo lalikulu, mwachitsanzo, 0.025 wt.%.ndi 1.17, 0.05 wt.% ndi 1.19 ndi 0.1 wt.% ndi 1.26.Pakadali pano, mfundo za PEC zogwiritsa ntchito nanofluids (GNPs-COOH@DW) zinali 1.02 kwa 0.025 wt%, 1.05 kwa 0.05 wt%, 1.05 kwa 0.1 wt%.muzochitika zonsezi (makona a helix 45 ° ndi 90 °).1.02.Monga lamulo, ndi kuwonjezeka kwa chiwerengero cha Reynolds, mphamvu ya kutentha-hydraulic imachepa kwambiri.Pamene chiwerengero cha Reynolds chikuwonjezeka, kuchepa kwa kutentha kwa kutentha-hydraulic coefficient kumagwirizana mwadongosolo ndi kuwonjezeka kwa (NuNFs / NuDW) ndi kuchepa kwa (fNFs / fDW).
Mphamvu ya Hydrothermal ya nanofluids potengera madzi oyambira kutengera manambala a Reynolds a machubu okhala ndi ngodya za 45 ° ndi 90 °.
Gawoli likufotokoza za kutentha kwa madzi (DW), non-covalent (VNP-SDBS@DW), ndi covalent (VNP-COOH@DW) nanofluids pamagulu atatu osiyana a misa ndi manambala a Reynolds.Ma geometries awiri ophimbidwa ndi lamba wosinthira amaganiziridwa mumtundu wa 7000 ≤ Re ≤ 17000 potengera mapaipi wamba (makona a helix 45 ° ndi 90 °) kuti awone momwe matenthedwe amagwirira ntchito.Pa mkuyu.10 imasonyeza kutentha kwa madzi ndi ma nanofluids pamalo otuluka monga momwe amagwiritsira ntchito (helix angle 45° ndi 90°) pa chitoliro wamba (\(\frac{{{T}_{out}}_{Twisted}}{{ {T} _{kutuluka}}_{Wanthawi zonse}}\)).Non-covalent (GNP-SDBS@DW) ndi covalent (GNP-COOH@DW) nanofluids ali ndi magawo atatu olemera osiyanasiyana monga 0.025 wt%, 0.05 wt% ndi 0.1 wt%.Monga momwe tawonetsera mkuyu.11, mtengo wapakati wa kutentha kotuluka (\(\frac{{{T}_{out}}_{Twisted}}{{{T}_{out}}_{Plain}}\)) > 1, kusonyeza kuti (45 ° ndi 90 ° helix angle) kutentha pa kutuluka kwa exchanger kutentha ndi ofunika kwambiri kuposa chitoliro wamba, chifukwa cha mphamvu ya chipwirikiti ndi bwino kusakaniza madzimadzi.Kuphatikiza apo, kutentha kwa DW, non-covalent ndi covalent nanofluids kunachepa ndi kuchuluka kwa Reynolds.Madzi a m'munsi (DW) ali ndi kutentha kwakukulu kwambiri komwe kumatuluka.Pakadali pano, mtengo wotsika kwambiri umanena za 0.1 wt% -SDBS@GNPs.Non-covalent (GNPs-SDBS@DW) ma nanofluids adawonetsa kutentha kwapakati poyerekeza ndi covalent (GNPs-COOH@DW) nanofluids.Popeza tepi yokhotakhota imapangitsa kuti malo othamanga akhale osakanikirana, kutentha kwapafupi ndi khoma kumatha kudutsa mumadzimadzi, ndikuwonjezera kutentha.Chiŵerengero chochepa cha twist-to-tepi chimabweretsa malowedwe abwinoko motero kutentha kwabwinoko.Kumbali inayi, zitha kuwoneka kuti tepi yopindidwayo imakhala ndi kutentha kochepa pakhoma, zomwe zimawonjezera Nuavg.Pazoyika tepi zopotoka, mtengo wapamwamba wa Nuavg ukuwonetsa kusintha kwa kutentha kwa convective mkati mwa chubu22.Chifukwa cha njira yowonjezereka yothamanga komanso kusakanikirana kowonjezereka ndi chipwirikiti, nthawi yokhalamo imawonjezeka, zomwe zimapangitsa kuti kutentha kwamadzimadzi kumawonjezeka pa kutuluka41.
Reynolds manambala osiyanasiyana a nanofluids okhudzana ndi kutentha kotuluka kwa machubu wamba (45 ° ndi 90 ° helix angles).
Ma coefficients otengera kutentha (45° ndi 90° helix angle) motsutsana ndi manambala a Reynolds a nanofluids osiyanasiyana poyerekeza ndi machubu wamba.
Njira yaikulu yowonjezera kutentha kwa tepi yowonongeka ndi iyi: 1. Kuchepetsa hydraulic diameter ya chubu chosinthira kutentha kumabweretsa kuwonjezeka kwa kuthamanga kwa kuthamanga ndi kupindika, zomwe zimawonjezera kumeta ubweya pakhoma ndikulimbikitsa kuyenda kwachiwiri.2. Chifukwa cha kutsekeka kwa tepi yokhotakhota, kuthamanga kwa khoma la chitoliro kumawonjezeka, ndipo makulidwe a malire amachepa.3. Kuthamanga kozungulira kumbuyo kwa lamba wopotoka kumabweretsa kuwonjezeka kwa liwiro.4. Ma vortices opangidwa amawongolera kusakaniza kwamadzimadzi pakati pa zigawo zapakati ndi pafupi ndi khoma zakuyenda42.Pa mkuyu.11 ndi fg.12 ikuwonetsa kutentha kwa DW ndi nanofluids, mwachitsanzo (kutengera kutentha kwapakati ndi nambala ya Nusselt) monga mavareji ogwiritsira ntchito machubu oyika tepi opotoka poyerekeza ndi machubu wamba.Non-covalent (GNP-SDBS@DW) ndi covalent (GNP-COOH@DW) nanofluids ali ndi magawo atatu olemera osiyanasiyana monga 0.025 wt%, 0.05 wt% ndi 0.1 wt%.M'malo onse otentha kutentha (45 ° ndi 90 ° helix angle) kutentha kwapakati kumakhala > 1, kusonyeza kusintha kwa kutentha kwapakati komanso chiwerengero cha Nusselt chokhala ndi machubu opiringidwa poyerekeza ndi machubu wamba.Non-covalent (GNPs-SDBS@DW) ma nanofluids adawonetsa kusintha kwakukulu kwa kutentha kwapakati kuposa covalent (GNPs-COOH@DW) nanofluids.Pa Re = 900, kusintha kwa 0.1 wt% pakusintha kutentha -SDBS@GNPs kwa osinthanitsa kutentha awiri (45 ° ndi 90 ° helix angle) anali apamwamba kwambiri ndi mtengo wa 1.90.Izi zikutanthauza kuti yunifolomu TP zotsatira ndizofunikira kwambiri pamayendedwe otsika amadzimadzi (nambala ya Reynolds) 43 ndikuwonjezera chipwirikiti.Chifukwa cha kuyambitsidwa kwa ma vortices angapo, kuchuluka kwa kutentha kwapakati komanso kuchuluka kwa machubu a TT a Nusselt ndi apamwamba kuposa machubu wamba, zomwe zimapangitsa kuti malirewo akhale ochepa.Kodi kukhalapo kwa HP kumawonjezera kuchulukira kwa chipwirikiti, kusakanikirana kwamadzimadzi ogwirira ntchito ndi kupititsa patsogolo kutentha kwa kutentha poyerekeza ndi mapaipi oyambira (popanda kuyika tepi yopotoka)21.
Avereji ya nambala ya Nusselt (makona a helix 45° ndi 90°) poyerekeza ndi nambala ya Reynolds ya ma nanofluids osiyanasiyana poyerekeza ndi machubu wamba.
Zithunzi 13 ndi 14 zikuwonetsa kugunda kwapakati (\(\frac{{f}_{Twisted}}{{f}_{Plain}}\)) ndi kutsika kwamphamvu (\(\frac{{\Delta P} _ {Twisted}}{{\Delta P}_{Plain}}\}} pafupifupi 45° ndi 90° pa mapaipi wamba pogwiritsa ntchito DW nanofluids, (GNPs-SDBS@DW) ndi (GNPs-COOH@DW) exchanger ion muli ( 0.025 wt %, 0.05 wt % ndi 0.1 wt %). { {f}_{Plain} }\)) ndi kutaya mphamvu (\(\frac{{\Delta P}_{Twisted}}{{\ Delta P }_{Plain}}\}) kuchepa. milandu, friction coefficient ndi kuthamanga kutayika kumakhala kwakukulu pamanambala otsika a Reynolds Avereji ya friction coefficient ndi kutsika kwamphamvu kuli pakati pa 3.78 ndi 3.12 Kugunda kwapakati ndi kutayika kwamphamvu kumawonetsa (45° helix angle ndi 90 °) kutentha exchanger ndalama kuwirikiza katatu kuposa mapaipi ochiritsira.Kuonjezera apo, pamene madzimadzi ogwira ntchito akuyenda pa liwiro lapamwamba, coefficient of friction imachepa. amachepetsa, zomwe zimabweretsa kuchepa kwa mphamvu ya viscosity yamphamvu pa malo okhudzidwa, kuchepa kwa liwiro la gradient ndi kumeta ubweya ndipo, chifukwa chake, kuchepa kwa coefficient of friction21.Kutsekeka kwabwinoko chifukwa cha kukhalapo kwa TT komanso kugwedezeka kowonjezereka kumabweretsa kutayika kwakukulu kwa mapaipi a TT amitundu yosiyanasiyana kuposa mapaipi oyambira.Kuonjezera apo, pazitsulo zonse zapansi ndi TT chitoliro, zikhoza kuwoneka kuti kutsika kwapansi kumawonjezeka ndi liwiro la ntchito yamadzimadzi43.
Coefficient of friction (45° ndi 90° helix angle) motsutsana ndi nambala ya Reynolds ya ma nanofluids osiyanasiyana poyerekeza ndi machubu wamba.
Kutaya kwamphamvu (45 ° ndi 90 ° helix angle) ngati ntchito ya Reynolds nambala ya nanofluids yosiyanasiyana yokhudzana ndi chubu wamba.
Mwachidule, Chithunzi cha 15 chikuwonetsa zoyezetsa ntchito (PEC) za zosinthira kutentha zokhala ndi ma angles 45° ndi 90° poyerekeza ndi machubu opanda kanthu (\(\frac{{PEC}_{Twisted}}{{PEC}_{Plain}}}) ) ) mu (0.025 wt.%, 0.05 wt.% ndi 0.1 wt.%) pogwiritsa ntchito DV, (VNP-SDBS@DV) ndi covalent (VNP-COOH@DV) nanofluids.Mtengo (\(\frac{{PEC}_{Twisted}}{{PEC}_{Plain}}\)) > 1 muzochitika zonse ziwiri (45° ndi 90° helix angle) mu chojambulira kutentha.Kuphatikiza apo, (\(\frac{{PEC}_{Twisted}}{{PEC}_{Plain}}\)) imafika pamtengo wake wabwino kwambiri pa Re = 11,000.Chosinthitsa kutentha cha 90° chikuwonetsa kuwonjezeka pang'ono mu (\ (\frac{{PEC}_{Twisted}}{{PEC}_{Plain}}\)) poyerekeza ndi chotenthetsera cha 45°., Pa Re = 11,000 0.1 wt%-GNPs@SDBS imayimira apamwamba (\(\frac{{PEC}_{Twisted}}{{PEC}_{Plain}}\)) makonda, mwachitsanzo 1.25 pakona ya 45° yosinthira kutentha ndi 1.27 kwa 90 ° chowotcha pakona.Ndilo lalikulu kuposa gawo limodzi mwa magawo onse a magawo ambiri, zomwe zimasonyeza kuti mapaipi okhala ndi matepi opotoka amakhala apamwamba kuposa mapaipi wamba.Makamaka, kutentha kwabwinoko komwe kumaperekedwa ndi zoyika tepi kudapangitsa kuti kutayika kwachangu kuchuluke22.
Njira zogwirira ntchito za chiwerengero cha Reynolds cha nanofluids osiyanasiyana pokhudzana ndi machubu ochiritsira (45 ° ndi 90 ° helix angle).
Zowonjezera A zikuwonetsa ma streamline a 45 ° ndi 90 ° osinthanitsa kutentha pa Re = 7000 pogwiritsa ntchito DW, 0.1 wt%-GNP-SDBS@DW ndi 0.1 wt%-GNP-COOH@DW.Ma streamline mu ndege yodutsa ndi chinthu chochititsa chidwi kwambiri cha zotsatira za zopindika za riboni pamayendedwe akuluakulu.Kugwiritsiridwa ntchito kwa 45 ° ndi 90 ° osinthanitsa kutentha kumasonyeza kuti liwiro la pafupi ndi khoma lapafupi ndilofanana.Pakadali pano, Zowonjezera B zikuwonetsa ma contours a liwiro la 45 ° ndi 90 ° osinthanitsa kutentha pa Re = 7000 pogwiritsa ntchito DW, 0.1 wt%-GNP-SDBS@DW ndi 0.1 wt%-GNP-COOH@DW.Malupu othamanga ali m'malo atatu osiyanasiyana (magawo), mwachitsanzo, Plain-1 (P1 = -30mm), Plain-4 (P4 = 60mm) ndi Plain-7 (P7 = 150mm).Mayendedwe othamanga pafupi ndi khoma la chitoliro ndi otsika kwambiri ndipo kuthamanga kwamadzimadzi kumawonjezeka chapakati pa chitoliro.Kuphatikiza apo, podutsa munjira ya mpweya, malo otsika kwambiri pafupi ndi khoma amawonjezeka.Izi zimachitika chifukwa cha kukula kwa hydrodynamic boundary layer, yomwe imawonjezera makulidwe a dera lotsika kwambiri pafupi ndi khoma.Kuphatikiza apo, kuwonjezera chiwerengero cha Reynolds kumawonjezera kuchuluka kwa liwiro m'magawo onse odutsa, motero kumachepetsa makulidwe a dera lotsika kwambiri mu channel39.
Ma graphene nanosheets ogwirizana komanso osagwira ntchito bwino adawunikidwa m'malo opindika a tepi okhala ndi ngodya za helix za 45 ° ndi 90 °.Chotenthetsera kutentha chimathetsedwa mwachiwerengero pogwiritsa ntchito SST k-omega turbulence model pa 7000 ≤ Re ≤ 17000. Thermophysical properties imawerengedwa pa Tin = 308 K. Panthawi imodzimodziyo kutentha khoma lopotoka la chubu pa kutentha kosalekeza kwa 330 K. COOH@DV) idachepetsedwa mumiyeso itatu, mwachitsanzo (0.025 wt.%, 0.05 wt.% ndi 0.1 wt.%).Kafukufuku wapano adaganizira zinthu zazikulu zisanu ndi chimodzi: kutentha kwa kutuluka, kutentha kwapakati, chiwerengero cha Nusselt, coefficient of friction, kutayika kwa mphamvu, ndi njira zowunikira ntchito.Nazi zotsatira zazikulu:
Kutentha kwapakati (\({{T}_{out}}_{Nanofluids}\)/\({{T}_{out}}_{Basefluid}\)) kumakhala kosakwana 1, kutanthauza kuti non-spread The outlet temperature of valence (ZNP-SDBS@DV) and covalent (ZNP-COOH@DV) nanofluids ndi yotsika kuposa ya madzi oyambira.Pakadali pano, kutentha kwapakati (\({{T}_{kunja}}_{Twisted}\)/\({{T}_{out}}_{Plain}\))) mtengo> 1, kusonyeza mfundo yakuti (45 ° ndi 90 ° helix angle) kutentha kotuluka ndi kwakukulu kusiyana ndi machubu ochiritsira.
Muzochitika zonsezi, kuchuluka kwazinthu zotengera kutentha (nanofluid/base fluid) ndi (chubu chopindika/chubu wamba) nthawi zonse zimawonetsa> 1.Non-covalent (GNPs-SDBS@DW) nanofluids anasonyeza apamwamba avareji kuwonjezeka kutentha kusamutsa, lolingana covalent (GNPs-COOH@DW) nanofluids.
Avereji ya friction coefficient (\({f}_{Nanofluids}/{f}_{Basefluid}\)) ya non-covalent (VNP-SDBS@DW) ndi covalent (VNP-COOH@DW) nanofluids nthawi zonse imakhala ≈1 .friction of non-covalent (ZNP-SDBS@DV) and covalent (ZNP-COOH@DV) nanofluids (\({f}_{Twisted}/{f}_{Plain}\)) kwa nthawi zonse > 3.
Muzochitika zonse ziwiri (45° ndi 90° helix angle), ma nanofluids (GNPs-SDBS@DW) adawonetsa apamwamba (\({\Delta P}_{Nanofluids}/{\Delta P}_{Basefluid}\)) 0.025 wt .% kwa 2.04%, 0.05 wt.% kwa 2.46% ndi 0.1 wt.% kwa 3.44%.Pakadali pano, (GNPs-COOH@DW) ma nanofluids adawonetsa kutsika (\({\Delta P}_{Nanofluids}/{\Delta P}_{Basefluid}\)) kuchokera ku 1.31% kwa 0.025 wt.% mpaka 1.65% ndi 0.05% % pa kulemera.Kuphatikiza apo, kutayika kwapakati (\({\Delta P}_{Twisted}/{\Delta P}_{Plain}\) of non-covalent (GNPs-SDBS@DW) ndi covalent (GNPs-COOH@DW) ))) nanofluids nthawi zonse>3.
Munthawi zonse (45° ndi 90° helix angles), ma nanofluids (GNPs-SDBS@DW) adawonetsa kuchuluka (\({PEC}_{Nanofluids}/{PEC} _{Basefluid}\)) @DW mtengo) , mwachitsanzo 0.025 wt.% – 1.17, 0.05 wt.% – 1.19, 0.1 wt.% – 1.26.Pamenepa, mfundo za (\({PEC}_{Nanofluids}/{PEC}_{Basefluid}\)) pogwiritsa ntchito (GNPs-COOH@DW) nanofluids ndi 1.02 pa 0.025 wt.%, 1.05 pa 0 ndi ,05w.% ndi 1.02 ndi 0.1% polemera.Kuphatikiza apo, pa Re = 11,000, 0.1 wt%-GNPs@SDBS adawonetsa zinthu zapamwamba (\({PEC}_{Twisted}/{PEC}_{Plain}\)), monga 1.25 kwa 45° helix angle ndi 90 ° helix angle 1.27.
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