A spherical water drop is suspended from a fine thread in still, dry air. Show:(a) That the Sherwood...

Question

A spherical water drop is suspended from a fine thread in still, dry air. Show:
(a) That the Sherwood number for mass transfer from the surface of the drop into the surroundings has a value of 2 if the characteristic length is the diameter of the drop. If the initial drop diameter is 1 mm, the air temperature is 38oC, the drop temperature is 14.4oC, and the pressure is 1 atm, calculate:
(b) The initial mass of the drop in grams.
(c) The initial rate of evaporation in grams per second.
(d) The time in seconds for the drop diameter to be reduced to 0.2 mm.
(e) The initial rate of heat transfer to the drop. If the Nusselt number is also 2, is the rate of heat transfer sufficient to supply the heat of vaporization and sensible heat of the evaporated water? If not, what will happen?

Robert · Accepted Answer

Capsule Questions
Earning Potential (1 Year) : 65.00 
notified on: Mar 15, 2017 03:18 AM
Title  
A spherical water drop is suspended from a fine thread 
Description  
A spherical water drop is suspended from a fine thread in still, dry air. Show: 
(a) That the Sherwood number for mass transfer from the surface of the drop into the 
surroundings has a value of 2 if the characteristic length is the diameter of the drop. If the initial 
drop diameter is 1 mm, the air temperature is 38oC, the drop temperature is 14.4oC, and the 
pressure is 1 atm, calculate:  
(b) The initial mass of the drop in grams. 
(c) The initial rate of evaporation in grams per second. 
(d) The time in seconds for the drop diameter to be reduced to 0.2 mm. 
(e) The initial rate of heat transfer to the drop. If the Nusselt number is also 2, is the rate of heat 
transfer sufficient to supply the heat of vaporization and sensible heat of the evaporated water? If 
not, what will happen?
Your Answer  
Attach files
view history  
Answer Text 
part    a 
Sherwwod  no  =  k / D /L=  k *  L  /D     
 [  Here  ,   k  = mass  transfer  coefficient  ,  D  =  diffusivity   (  m2  /s  )    .  L  = d  = 
diameter   =   1 mm  =  1/1000  =0.001 m=  L ] 
Sh  =  k*L /D  
  2  =  k*  0.

A spherical water drop is suspended from a fine thread in still, dry air. Show: (a) That the Sherwood number for mass transfer from the surface of the drop into the surroundings has a value of 2 if...

Solution

Answer To This Question Is Available To Download

Related Questions & Answers

Submit New Assignment