In [1]:

```
import math
# Variables
D = 0.025; #Diameter of the cylinder in m
R = (2*10**-6); #Rate of sublime in kg/s
C = (6*10**-6); #Saturated vapour concentration in kmol/m**3
W = 128; #Molecular weight in kg/kmol
# Calculations
q = (R/W); #Molar transfer rate in k.mol/sm
h = (q/(math.pi*D*C)); #Convective mass transfer coefficient in m/s
# Results
print 'Convective mass transfer coefficient is %3.3f m/s'%(h)
```

In [7]:

```
import math
# Variables
pA = -0.9; #Partial pressure of water vapour in atm
t = 0.0025; #Boundary layer thickness in m
# Calculations
y = 0;
pAs1 = math.exp(-33.35*y)-0.9; #Partial pressure in atm
y = t;
pAs2 = math.exp(-33.35*y)-0.9; #Partial pressure in atm
#partial derivative of pA wrt y is -33.35exp(y)-0.9
x = 0;
X = (-33.35*math.exp(x))-pA; #Partial derivative value at x = 0
DAB = (0.26*10**-4) #DAB value in m**2/s
h = (DAB*X)/(pAs2-pAs1); #Local mass transfer coefficient in m/s
# Results
print 'Local mass transfer coefficient is %3.3f m/s'%(h)
```

In [3]:

```
# Variables
T = 27; #Temperature of dry air in degree C
p = 1; #Pressure of dry air in atm
L = 0.5; #Length of the plate in m
v = 50; #Velocity in m/s
# Calculations
DAB = (0.26*10**-4) #DAB value in m**2/s
p = 1.16; #Density in kg/m**3
u = (184.6*10**-7); #Dynamic viscosity in N.s/m**2
Pr = 0.707; #Prantl number
Sc = (u/(p*DAB)); #Schmidt number
Re = (p*v*L)/u; #Reynolds number
jm = (0.0296*(Re**(-1./5))); #jm value
h = (jm*v)/Sc**(2./3); #Mass transfer coefficient of water vapour in m/s
# Results
print 'Mass transfer coefficient of water vapour is %3.3f m/s'%(h)
```

In [5]:

```
# Variables
T = 27; #Temperature of swimming pool in degree C
h = 0.4; #Relative humidity
v = 2; #Speed of wind in m/s
v1 = (15.89*10**-6); #Kinematic viscosity in m**2/s
p = 0.0436; #Density in kg/m**3
DAB = (0.26*10**-4) #DAB value in m**2/s
L = 15; #Length in m
# Calculations
Sc = (v1/DAB); #Schmidt number
Re = (v*L)/v1; #Reynolds number
ShL = (((0.037*Re**(4./5))-870)*Sc**(1./3)); #Equivalent Schmidt number
h1 = (ShL*(DAB/L))/10**-3; #Mass transfer coefficient for evaporation in mm/s
# Results
print 'Mass transfer coefficient for evaporation is %3.1f*10**-3 m/s'%(h1)
```

In [6]:

```
# Variables
T = 25; #Temperature of air in degree C
v = 3; #Velocity im m/s
D = 0.01; #Diameter of tube in m
L = 1; #Length of tube in m
# Calculations
v1 = (15.7*10**-6); #Kinematic viscosity in m**2/s
DAB = (0.62*10**-5) #DAB value in m**2/s
Re = (v*D)/v1; #Reynolds number
Sh = 3.66; #Schmidt number
h = (Sh*DAB)/D; #Average mass transfer coefficient in m/s
# Results
print 'Average mass transfer coefficient is %3.5f m/s'%(h)
```

In [8]:

```
# Variables
T = 25; #Temperature of air in degree C
v = 5; #Velocity in m/s
D = 0.03; #Diameter of tube in m
DAB = (0.82*10**-5) #DAB value in m**2/s
# Calculations
v1 = (15.7*10**-6); #Kinematic viscosity in m**2/s
Sc = (v1/DAB); #Schnidt number
Re = (v*D)/v1; #Reynolds number
h = (0.023*Re**(4./5)*Sc**(1./3)*DAB)/D; #Mass transfer coefficient in m/s
# Results
print 'Mass transfer coefficient is %3.4f m/s'%(h)
```

In [9]:

```
import math
# Variables
Ta = 40.+273; #Temperature of air in K
w = 100.; #Molecular weight in kg/k.mol
H = 120.; #Latent heat of vapourisation of volatile liquid in kJ/kg
p = 3530.; #Saturated vapour pressure in N/m**2
DAB = (0.2*10**-4); #DAB value in m**2/s
# Calculations
p1 = 1.16; #Density in kg/m**2
Cp = 1.007; #Specific heat in J/kg.K
a = (22.5*10**-6); #Diffusivity in m**2/s
X = ((H*100*p*10**-3)/(8.315*p1*Cp*(a/DAB)**(2./3))); #X value for temperature
T = (Ta+math.sqrt((Ta**2-(4*X))))*0.5; #Temperature in K
# Results
print 'Steady state temperature of cold water inside the pot is %3.1f K'%(T)
```

In [10]:

```
# Variables
T = 22. + 273; #Thermometer reading in K
# Calculations
p = 2617; #Pressure in N/m**2
hfg = 2449; #Enthalpy in kJ/kg
p1 = (p*18)/(8315*T); #Density in kg/m**3
p2 = (1.0132*10**5)/(287*T); #Density in kg/m**3
Cp = 1.008; #Specific heat in kJ/kg.K
a = (26.2*10**-6); #Diffusivity in m**2/s
DAB = (0.26*10**-4); #DAB value in m**2/s
Ts = ((T-273)+((hfg*1000*p1)/(p2*Cp*1000))); #True air temperature in degree C
# Results
print 'True air temperature is %3.2f degree C'%(Ts)
```

In [11]:

```
# Variables
T = 50.; #Temperature of air stream in degree C
Tb = 22.; #Bulb temperature in degree C
# Calculations
Tf = (T+Tb)/2; #Film temperature in degree C
p = 1.14; #Density in kg/m**3
Cp = 1.006; #Specific heat in J/kg.K
Pr = 0.7; #Prantl number
u = (2*10**-5); #Dynamic viscosity in Ns/m**2
DAB = (0.26*10**-4); #DAB value in m**2/s
Sc = (u/(p*DAB)); #Schmidt nuber
Le = (Sc/Pr); #Lewis number
p1 = 0.01920; #Density in kg/m**3
hfg = 2449; #Enthalpy in kJ/kg
pA = 0.0064; #Density in kg/m**3
psat = (1./12.23); #Saturation density in kg/m**3
RH = (pA/0.0817)*100; #Relative humidity
# Results
print 'Relative humidity of the airstream is %3.2f percent'%(RH)
```

In [12]:

```
# Variables
Td = 27.; #Dry bulb teperature in degree C
Tw = 17.; #Wet bulb temperature in degree C
Pr = 0.74; #Prantl number
Sc = 0.6; #Schmidt number
Mv = 18.; #Molecular weight of vapour
Ma = 29.; #Molecular weight of air
Cp = 1004.; #Specific heat in J/kg.K
p = (1.0132*10**5); #Pressure in N/m**2
# Calculations
pv2 = 1917; #Saturation presusre of air at 17 degree C in N/m**2
hfg = 2461; #Enthalpy in kJ/kg
w2 = (Mv*pv2)/(Ma*(p-pv2)); #Weight in kg/kg of dry air
w1 = w2-((Cp*(Pr/Sc)**(2./3)*(Td-Tw))/(hfg*1000)); #Specific humidity of air in kg/kg of dry air
# Results
print 'Specific humidity of air is %3.5f kg/kg of dry air'%(w1)
```

In [4]:

```
# Variables
T = 27.; #Temperature of swimming pool in degree C
Ts = 37.; #Surface temperature in degree C
h = 0.4; #Relative humidity
D1 = 5.; #Dimension of swimming pool in m
D2 = 15.; #Dimension of swimming pool in m
v = 2.; #Speed of wind in m/s
v1 = (15.89*10**-6); #Kinematic viscosity in m**2/s
p = 0.0436; #Density in kg/m**3
DAB = (0.26*10**-4) #DAB value in m**2/s
Sc = (v1/DAB); #Schmidt number
Re = (v*D2)/v1; #Reynolds number
ShL = (((0.037*Re**(4./5))-870)*Sc**(1./3)); #Equivalent Schmidt number
h1 = (ShL*(DAB/D2)); #Mass transfer coefficient for evaporation in m/s
# Calculations
Psat = 3531.; #Partial pressure of water vapour in N/m**2
pi = (0.4*6221); #Saturation pressure of water vapour in N/m**2
pt = 101325.; #Total pressure of air in N/m**2
pAs = (18*Psat)/(8361*(T+273)); #Density at the water surface in kg/m
pAi = (18*pi)/(8316*(T+273)); #Density at the water surface in kg/m
n = round((h1*(pAs-pAi)*3600*24),); #Rate of evaporation of water in kg/m**2 day
L = (n*D1*D2); #Total water loss from the swimming pool in kg/day
# Results
print 'Rate of evaporation of water is %3.1f kg/day'%(L)
# there is a rounding off error in textbook.
```

In [ ]:

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```