Lub Siab -Kev Sib Tw Muaj Peev Xwm Kub hauv Molten Salt Storage
Rubidium nitrate (RbNO₃) melts ntawm 300℃rau thermal zog cia daim ntaub ntawv. PFA, PVDF, thiab ETFE sheaths raug soj ntsuam rau luv luv - lub sij hawm dhau - qhov kub thiab txias muaj peev xwm thaum lub sij hawm melt startup thiab txhaum tej yam kev mob. Thermogravimetric tsom xam (TGA) nyob rau hauv inert cua (nitrogen) piv decomposition pib kub. Kev soj ntsuam ntau los ntawm 5 lub chaw soj nstuam thermal qhia tau tias PFA tiv taus 350℃rau 30 vib nas this nrog<0.1% mass loss, while PVDF decomposes at 300°C and ETFE at 320°C, making PFA the only viable option for RbNO₃ service with over-temperature margin.
TGA Comparison Nyob rau hauv Inert Atmosphere
TGA ntawm 10℃/ min hauv nitrogen, ntxiv rau isothermal tuav ntawm 350℃rau 30 vib nas this:
| Polymer | Kev siv tsis tu ncua Temp (degree) | Decomposition pib (degree) | Loj poob ntawm 350℃/ 30s | Loj poob ntawm 380℃/ 30s | Haum rau RbNO₃ (300 degree) |
|---|---|---|---|---|---|
| PVDF | 150 | 300 | 5% (decomposes ntawm 300 degree, N / A ntawm 350 degree) | 20% | Tsis muaj |
| ETFE | 150 | 320 | 2% | 8% | Marginal |
| Standard PFA | 260 | 360 | 0.08% | 0.5% | Yog lawm |
| Siab -PFA purity | 260 | 370 | 0.05% | 0.3% | Yog lawm |
| Txhawb PFA | 260 | 355 | 0.10% | 0.6% | Yog lawm |
RbNO₃ Chemical Compatibility
Molten RbNO₃ ntawm 300℃yog oxidizing tus neeg sawv cev. Compatibility test nrog polymer sheaths:
| Polymer | Tawm tsam los ntawm RbNO₃ ntawm 300 degree | Cov khoom siv tshuaj tiv thaiv | Tus nqi degradation |
|---|---|---|---|
| PVDF | Mob hnyav | HF, CO₂, nitrogen oxides | Ceev (feeb) |
| ETFE | Nruab nrab | HF, CO₂ | Teev |
| PFA | Tsawg kawg | Trace CO₂, tsis muaj HF | Tsis tsim nyog (xyoo) |
PFA tus qauv perfluorinated tiv taus nitrate oxidation.
Tshaj -Tub muaj peev xwm tiv thaiv kev ua txhaum
Thaum RbNO₃ melt startup lossis localized overheating, sheath kub yuav tshaj 300 degree. Yuav tsum muaj luv luv - lub sijhawm muaj peev xwm:
| Fault Scenario | Kub | Duration | PFA Ciaj sia nyob | PVDF/ETFE Ciaj sia taus |
|---|---|---|---|---|
| Kev ua haujlwm li qub | 300 degree | Tsis tu ncua | Yog lawm | Tsis muaj |
| Startup overshoot | 320 degree | 60 vib nas this | Yog lawm | Marginal (ETFE) |
| Localized kub qhov chaw | 350 degree | 30 vib nas this | Yog lawm | Tsis muaj |
| Ua txhaum loj | 380 degree | 10 vib nas this | Txais tau (0.3% poob) | Tsis muaj |
| Kev puas tsuaj | 400 degree | >10 vib nas this | Decomposition | Tsis muaj |
Phab ntsa Thickness thiab Thermal Inertia
Thicker PFA phab ntsa muab cov thermal buffering thaum dhau - kub:
| Phab ntsa Thickness | Lub sij hawm ntawm 300℃txog 350℃ntawm 15 W / cm² (sec) | Lub sij hawm ntawm 350℃mus rau 380℃(sec) | Tag Nrho Cov Qhov rai Zoo (txog 380 degree) |
|---|---|---|---|
| 1.5 hli | 12 | 8 | 20 sec |
| 2.0 hli | 18 | 12 | 30 sec |
| 2.5 hli | 25 | 16 | 41 nqi |
| 3.0mm ib | 32 | 20 | 52 nqi |
Mechanical Property Retention tom qab tshaj -Tsub
Tom qab 350℃/ 30-thib ob raug, PFA khaws cov khoom siv kho kom txaus rau kev pabcuam txuas ntxiv:
| Khoom | Ua ntej raug | Tom qab 350℃/ 30s | Khaws cia |
|---|---|---|---|
| Tensile zog (MPa) | 28 | 26 | 93% |
| Elongation (%) | 300 | 270 | 90% |
| Ntug D hardness | 65 | 67 | +2 |
| Dielectric zog (kV / mm) | 20 | 19.5 | 98% |
Kev taw qhia tshwj xeeb rau RbNO₃ Thermal Storage
Rau rubidium nitrate melts ntawm 300 degree, qhia siab -purity PFA (tsawg kawg pawg) nrog phab ntsa thickness 2.5 hli yam tsawg kawg nkaus. Yuav tsum tau TGA ntawv pov thawj qhia<0.2% mass loss at 350°C for 60 seconds under nitrogen. PVDF and ETFE are not recommended for this service due to decomposition below 320°C. For thermal energy storage systems with potential for temperature excursions to 350°C, specify 3.0mm walls and implement over-temperature protection set at 340°C. The premium for PFA over PVDF/ETFE (2-3x higher cost) is justified by enabling molten nitrate salt storage at 300°C where alternative polymers would fail within hours. For research-scale systems with precise temperature control (<±5°C), standard PFA with 2.0mm walls may be acceptable.
