Stanton Number

University:
Duke University
Course:
PHYSICS 814 | Introduction to Fluid Mechanics
Academic year:

2023
Views:

182

Pages:

2
Author:

Pemuda H

εν au plr+E)ay () 9" = = TW-T Too EnCp(Tw-Too)() = = + Jow hf pūp En = 2 = hf St pup Stanton Number Is this much different from other numbers? Nux Rex Pr St= = hex. K. K hf Kucp pux = pūcp Nope! For a long tube hfD K 0.023 0.33 (PTD) 0.8 (MC) Rep Pr from experiments Nuo → hf -0.2 -0.67 = 0.023 Rep Pr -0.2 →½ Cf = 0.023 Rep St = ½ CFP 0.67 No definition of St. number Chilton-Colburn Analogy (4.3.2.2) Flat Plate 2 Cf = hf PC plus Pr 0.67 Ex.) Prob. 11 pg. 34 Ua=1603 T= 3000K Di = 30cm Steel A= thickness = 2.5mm S= 6.1mm space Uc= 10 Tc 15°C Pa = 140 kPa FIND: TWh=? A=hfa (Ta-Twn) heat flux is the same throughout the pipe Twh-TWC A = K Δ = hfc (Twc-Tc) hATa-Twn = =K(Twh-TWC) hfcA = Add them up -(nen + x + htc ) = Ta-Twh+ hfa have Twh Twe +Twc-Tc - Ta-To hfa= Ta Twh Divide these two K hfc ++ hfa Ta-Tc Ta-Twh Ksteel E (14, 60) mk = W 20 m.K J →Cpair 1291.5 kg Pr=0.8 tables: 50.9×10" NS m² μα (Τι) μα (12) → 72 Ma (3000K) = μα (1400 κ) (1400 3000 0.8 N m² = 855×10 Pa kg RTa 0.163 m³ ← Pa = hfa - 0.023 (PAD) 0.8 (MCP) 0.33 DK = 91.57 μ ms.K Do the same thing and hfc 26.87m².S.K => Twh = 327.8K, no more than three decimal places (impossible to measure). Look at notes from 6.2 to 6.3.5