Vim li cas PFA Rhaub nrog Roughened Sandblasted Surface Outperform Smooth Surface nyob rau hauv siab -Hloov Organic Solvent Heating?

Nyob rau hauv cov nqe lus ntawm kev ruaj ntseg zaj duab xis thiab nucleate boiling kub kis, ib tug roughened PFA nto (Ra 1.0–1.5 µm) nquag ua tau zoo dua ib tug du nto (Ra <0.2 µm) nyob rau hauv siab - siab organic hnyav cua sov (xws li, toluene, acetone, hexane ntawm 5–20 bar, 0 100). Bubble nucleation tswj yog lub tshuab; superheating thiab sai, sai boiling (bumping) tshwm sim los ntawm du nto suppressing npuas tsim. Cov coefficients hloov hluav taws xob ntau dua thiab zoo ib yam, me me - npuas npuas tau txhawb los ntawm qhov chaw roughened uas muaj cov chaw tswj cov nucleation. Tsis tas li ntawd, vim tias qhov ntxhib hauv sab hauv (yog tias sandblasted ua ntej extrusion) txhim kho kev sib tshuam ntawm PFA thiab hlau core, roughened nto resists hnyav -induced o delamination. Ib qho roughened nto tsub kom ntub dej thiab txo qhov kev pheej hmoo ntawm zaj duab xis boiling rau organic solvents uas ntub PFA tsis zoo (hu rau lub kaum sab xis> 90℃). Txhawm rau kom tau txais txiaj ntsig zoo, sab hauv sab hauv yuav tsum tau muab tshuaj etched rau adhesion thiab sab nrauv yuav tsum sandblasted (Ra 1.0-1.5 µm).

Boiling ntawm Nucleates thiab Nto Roughness
Lub tshav kub flux hauv cov kuab tshuaj organic rhuab nyob rau hauv lub siab yog nquag muaj zog txaus induce boiling ntawm PFA nto. Npuas nucleation ntawm ib tug du nto yuav tsum muaj ib tug loj npaum li cas ntawm superheat (ΔT=10-30℃tshaj boiling point). Qhov kub hauv zos nce los ntawm cov npuas uas tau loj heev thiab maj mam sib cais. Micro- kab noj hniav (5–20 µm) ntawm qhov chaw roughened ua hauj lwm raws li qhov chaw nucleation tsis tu ncua los ntawm ntxiab vapor. Thaum tshav kub kub hloov pauv tau zoo dua los ntawm cov npuas uas ua rau qis dua superheat (2-5 degree), me dua, thiab sib cais ntau zaus. Nyob rau tib lub tshav kub ntws, qhov roughened nto tej zaum yuav muaj 50-100% ntau dua tshav kub hloov coefficient (h).

Smooth PFA (Ra 0.1 µm) qhia zaj duab xis boiling ntawm 8 W / cm² nrog ΔT=40℃rau toluene ntawm 150℃thiab 10 bar. Ntawm ΔT=15℃, roughened PFA (Ra 1.2 µm) sustains nucleate boiling mus txog 15 W / cm².

Sib piv kev ua tau zoo hauv Organic Solvents ntawm Siab Siab
Solvent Pressure (bar) Temp (degree) Nto Finish Critical Heat Flux (W/cm²) Heat Transfer Coefficient (W/m²·K) Boiling Regime Relative Life
Toluene 10 150 Smooth (0.1) 6–8 1,500–2,000 Film boiling at >6 1.0x Toluene 10 150 Roughened (1.2) 12–15 3,000–4,000 Nucleate rau 12 2.5x
Acetone 8 120 Smooth 5–{2}},800–2,500 Pob 1.0x
Acetone 8 120 Roughened 10–{2}},500–5,000 Cov npuas ruaj khov 2.8x Hexane 5 100 Smooth 4–6 1,200–1,800 Hnyav kub 0.8x
Hexane 5 100 Roughened 8–{2}},500–3,500 Tswj 2.2x Ethanol 12 180 Smooth 7–9 2,000–2,500 Superheat 1.2x
Ethanol 12 180 Roughened 14–{2}},000–5,500 ruaj khov 2.5x
Mechanical Interlocking rau Adhesion
Sab hauv ntawm PFA sheath (tawm tsam cov tub ntxhais hlau) kuj tau txais txiaj ntsig los ntawm roughening. Sandblasting cov tub ntxhais hlau mus rau Ra 2-4 µm ua ntej PFA extrusion tsim cov khoom siv sib cuam tshuam. PFA anchors nws tus kheej los ntawm ntws mus rau saum npoo asperities. Cov kua dej tuaj yeem nthuav dav PFA (0.5-2% ntim nce) hauv siab -siab cov kuab tshuaj organic. Nyob rau hauv kev ntxhov siab o, ib qho kev sib tshuam (Ra <0.5 µm) yuav delaminate. Vim tias PFA raug kaw nyob rau hauv qhov chaw so, adhesion yog khaws cia ntawm qhov sib cuam tshuam (Ra> 2 µm). Rau kev cia siab rau lub sijhawm ntev, qhov no yog qhov tseem ceeb.

Kom tau txais cov txiaj ntsig zoo tshaj plaws, qhia:

Sandblasted rau Ra 1.0-1.5 µm rau sab nraud (rau npuas nucleation)

Sandblasted rau Ra 2.5-4.0 µm (rau adhesion) ntawm sab hauv (hlau core)

Hlau core nto: Chemically etched tom qab sandblasting kom tshem tawm cov khoom xoob thiab tsim nano-porosity

Thaum Smooth Surface Zoo dua
Smooth PFA nto tseem raug xaiv rau:

Tsis yog - boiling, ib zaug - cua sov theem: Tsis muaj npuas, yog li roughness tsuas yog txhawb fouling.

High -purity kev pab cuam: ntxhib nto sau impurities thiab yog nyuaj rau ntxuav.

Crystallizing lossis scaling fluids: Scale sticks nkag mus rau qhov chaw ntxhib.

Tsawg- kev pabcuam siab (<2 bar) where boiling is not a problem.

Piv txwv hauv Teb
Lub tshuab hluav taws xob PFA du tau siv rau hauv cov tshuaj reactor kom sov toluene ntawm 150℃thiab 10 bar. Tom qab 6 lub hlis, lub tshuab cua sov muaj qhov cuam tshuam loj thiab tawg sai sai, uas ua rau kub oscillations ntawm ± 15℃thiab PFA tawg. Lub roughened PFA rhaub (Ra 1.3 µm sab nrauv, Ra 3 µm core) tau teeb tsa hauv cov nroj tsuag. Lub tshuab cua sov tau siv sijhawm ntau tshaj peb xyoos, kev sib tsoo ploj, thiab kev tswj xyuas qhov kub thiab txias tau nce mus txog ± 2 degree. Tus nqi ntawm lub rhaub tau nce $ 100 vim yog sandblasting (15% ntxiv). Nws tau them rau hauv ob lub hlis ua tsaug rau kev txuag nyiaj los ntawm kev txo qis qis.

Kev tshuaj xyuas thiab kho
Rau roughened heaters hauv kev pabcuam, tshuaj xyuas rau:

Fouling: Deposits yog daig rau ntawm qhov chaw ntxhib. Siv txhuam txhuam thiab lub teeb hnyav los ntxuav; tsis txhob siv tej abrasives uas yuav du nto.

Kev hnav khaub ncaws saum npoo: Kev yaig tuaj yeem ua rau lub siab tshaj plaws nyob rau lub sijhawm peb mus rau tsib xyoos. Yog tias Ra txo qis dua 0.8 µm, rov-sandblast lossis hloov.

Adhesion test: Periodically ntsuam xyuas insulating kuj. Delamination ntawm qhov ntxhib interface yog qhia los ntawm kev poob, uas tsis tshua muaj.

Nyob rau hauv xaus, ib tug roughened nto txhim kho adhesion thiab boiling.
Rau siab - siab cov organic hnyav cua sov (5-20 bar, 100-200 degree), lub PFA rhaub nrog roughened sandblasting nto (Ra 1.0-1.5 µm) beats ib tug du nto los ntawm 2-3 × nyob rau hauv cov nqe lus ntawm ruaj khov nucleate boiling, siab dua kub kub flux, thiab tsis kam mus bumping. Cov txheej txheej ntxhib muab kev tswj cov npuas nucleation qhov chaw; qhov ntxhib sab hauv nto txhawb kev ua raws li cov kuab tshuaj-induced o. Qhia tshwj xeeb sandblasted PFA rau cov txheej txheem organic hnyav qhov twg boiling. Rau cov uas tsis yog- boiling, qis- siab, los yog siab - kev pab cuam purity, du yuav zoo tshaj plaws. Teem lub nto nrog txoj haujlwm. Bumps yog tsim nyog rau boiling. Xuab zeb yog tsim nyog rau pob. Xuab zeb rau saum npoo, boil tsis tu ncua, thiab ua siab ntev rau lub sijhawm ntev. Rough yog muaj zog hauv cov organics. Smooth yog nplua - thiab plam mus rau hauv zaj duab xis boiling. Xaiv qhov ntxhib.