From example 37 the diffusivity of methanol in water

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: nstead of American Engineering) units, 1 1 HL = CL 12 = 0.174 1/ 6 4hL DL au L 1/ 2 uL a a 1 1 = 1.08 12 aPh 1/ 6 4(0.0162)(0.947) (3.0 10-9 )(86.8)(0.00274) 1/ 2 0.00274 86.8 a aPh a m aPh To compute (aPh /a), we need for the liquid phase, the Reynolds, Weber, and Froude numbers from equations (6-138), (6-139), and (6-140), respectively, based on the packing hydraulic diameter from (6-137). d h = packing hydraulic diameter = 4 0.947 =4 = 0.0436 m = 0.143 ft 86.8 a Reynolds number = N ReL , h = u L d h L (0.00898)(0.143)(48) = = 262 [(0.35)(0.000672)] L Take the surface tension of methanol at 154oF as = 17 dynes/cm = 0.001165 lbf/ft or 0.001165(32.2) = 0.0375 lbm/s2 Weber number = N WeL ,h 2 u L L d h ( 0.00898 ) (48)(0.143) = = = 0.0148 0.0375 2 2 Froude number = N FrL , h ( 0.00898) = 0.0000175 u2 = L = gd h 32.2(0.143) From (6-136), aPh -1/ 2 = 1.5 ( ad h ) N Re L ,h a = 1.5 [ (86.8)(0.0436) ] ( ) (N -0.2 -1/ 2 We L , h ) (N ) 0.75 FrL , h -0.45 ( 262 ) ( 0.0148) ( 0.0000175) -0.2 0.75 -0.45 = 1.485 Exercise 7...
View Full Document

Ask a homework question - tutors are online