Answered step by step
Verified Expert Solution
Link Copied!

Question

1 Approved Answer

Please answer part A , B and C exactly as asked.????? Various industrial processes require that a flat sheet be coated with a uniform liquid

Please answer part A,B and C exactly as asked.?????
Various industrial processes require that a flat sheet be coated with a uniform liquid film. Dip coating is a procedure in which an immersed substrate is withdrawn through a liquid-gas interface. In the process in Figure 1, in which a substrate is pulled upward at a constant velocity V, the coating achieves a uniform thickness H at a certain height above the liquid. It is desired to predict H from V and the liquid properties , and ).
Figure 1. One side of a solid sheet being withdrawn upward from a liquid
a) Representative values are H=0.02 to 0.2cm,V=0.4 to 3cms,=0.3 to 2Pa*s,=900kgm3, and =30mNm. By examining the ranges of dimensionless groups, show that viscosity, gravity, and surface tension are all important, but inertia is not. (Use dimensionless group listed on Table 1.6(Deen))
Page 1 of 5
b) A theoretical result that is applicable here is
H(g)12=0.944(V)23(1-H2gV)23
Show that this may be rewritten as a relationship between Bo and Ca.
Here is the definition of Bo and Ca.
Bo=gL2-=GravitaionalSurfaceTension
Ca=U-=ViscousSurfaceTension
c) If one group is chosen now as N=(BoCa)12=[H2gvV]12 and Ca is the second group, show that
N(1-N2)23=0.944Ca16
Use this to derive explicit expressions for N for Ca0 and Ca. How does H vary with V in these limits?
image text in transcribed

Step by Step Solution

There are 3 Steps involved in it

Step: 1

blur-text-image

Get Instant Access to Expert-Tailored Solutions

See step-by-step solutions with expert insights and AI powered tools for academic success

Step: 2

blur-text-image

Step: 3

blur-text-image

Ace Your Homework with AI

Get the answers you need in no time with our AI-driven, step-by-step assistance

Get Started

Recommended Textbook for

Thermodynamics for Engineers

Authors: Kenneth A. Kroos, Merle C. Potter

1st edition

1133112862, 978-113311286

More Books

Students also viewed these Chemical Engineering questions