Lesson 6

Question 1

for _____________, in many cases, the rate of diffusion is slow

Answer 1

molecular diffusion

Question 2

when the fluid velocity is _____________, the rate of diffusion is slow

Answer 2

increased

Question 3

this usually requires the fluid to be flowing past by another immiscible fluid or by a solid surface

Answer 3

convective flow

Question 4

a circular movement of water, counter to the main current, causing a smal whirlpool

Answer 4

eddies

Question 5

in _____________, there are no streamlines

Answer 5

turbulent motion

Question 6

in this region, most of the mass transfer is by turbulent diffusion

Answer 6

turbulent region

Question 7

in this region, mass transfer is the sum of turbulent and molecular diffusion

Answer 7

transition or buffer region

Question 8

in this region, most mass transfer occurs by molecular diffusion, since few or no eddies are present

Answer 8

thin viscous sublayer film

Question 9

two typeof diffusion in convective mass transfer

Answer 9

1. equimolar counterdiffusion
2. unicomponent diffusion

Question 10

this indicates the degree of turbulence

Answer 10

reynold number

Question 11

it is the ratio of the kinematic viscosity (shear component) and the mass diffusivity

Answer 11

schmidt number

Question 12

this physically relates the relative thickness of the hydrodynamic later and mass-transfer boundary layer

Answer 12

schmidt number

Question 13

it is the ratio between the mass transfer by convection and the mass transfer by diffusion

Answer 13

sherwood number

Question 14

it is the ratio of the convective mass transfer to the flux due to the bulk flow of the medium

Answer 14

stanton number

Question 15

it is the ratio of the therml diffusivity and the mass diffusivity

Answer 15

lewis number

Question 16

it correlates momentum, heat and mass-transfer data. it allows to predict an unknown transfer coefficient with other known coefficients

Answer 16

JD Number

Question 17

types of mass transfer for flow inside pipes

Answer 17

1. laminar flow
2. turbulent flow

Question 18

types of mass transfer for flow outside solid surfaces

Answer 18

1. flow parallel to flat plates
2. flow past single spheres