# Chapter 7: Velocity Humidity and Moisture

### Example 7.1, Page NUmber: 436

In :
#variable declaration
f=2*9.8*10**5            # Force in Dynes
A=100.0                  # area in cm^2
V=20.0                   # velocity in m/sec
l=10.0                   # length in cm

#calculation
mu=(f/A)/(V/l)
mu=mu/1000.0

#result
print('The absolute viscosity mu = %.1f*10^5 centipoises'%mu)

The absolute viscosity mu = 9.8*10^5 centipoises

### Example 7.2, Page Number:437

In :
#(a)

#variable declaration
v=10.0                # absolute viscosity

#calculation
F=1/v

#result
print('(a)\nFluidity = %.1f rhe'%F)

#(b)

#variable declaration
mu=10.0                  # absolute viscosity
rho=0.8                  # density in m/cm^3

#calculation
ve=mu/rho

#result
print('\n(b)\nKinematic viscosity (v)= %.1f cm^2/sec'%ve)

#(c)

#variable declaration
ab=1000.0                # absolute viscosity
abwt=1.002               # absolute viscosity of water at 20 deree celcius

#calculation
rv=ab/abwt

#result
print('\n(c)\nRelative viscosity = %d centipoises'%rv)

#(d)

#variable declaration
PAS=10.0

#Result
print('\n(c)\nAbsolute viscosity = 1000 centipoises =10 poises = 1PAS')

(a)
Fluidity = 0.1 rhe

(b)
Kinematic viscosity (v)= 12.5 cm^2/sec

(c)
Relative viscosity = 998 centipoises

(c)
Absolute viscosity = 1000 centipoises =10 poises = 1PAS

### Example 7.3, Page Number: 438

In :
import math
#b)

#variable declaration
R=0.5                      # radius
L=5                        # length
p_diff=800.0               # pressure difference
V=10.0                     # volume

#calculation
mu=(math.pi*R**4)*p_diff/(8*V*L)

#result
print('(b)\nmu=%.4f poise =%.2f centipoise'%(mu,mu*100))

(b)
mu=0.3927 poise =39.27 centipoise

### Example 7.4, Page Number: 439

In :
import math
#(a)

#variable declaration
g=980.0                   # acceleration due to gravity
h=4                       # Height
R=0.5                     # radius
V=10.0                    # volume
l=5.0                     # length
t=1.0

#calculation
v=(math.pi*g*h*t*R**4)/(8*l*V)

#result
print('(a)\n v = %.2f stokes'%v)

#calculation
mu=0.3925
rho=mu/v

#result
print('\n(b)\n Density of the fluid rho = %.3f gm/cm^3'%rho)

(a)
v = 1.92 stokes

(b)
Density of the fluid rho = 0.204 gm/cm^3

### Example 7.5, Page Number: 440

In :
#variable declaration

#(a)
A=0.226      # value of A as per equation
B=195.0      # value of B as per equation
t=60.0       # Efflux time

#calcullation
v=A*t-B/t
A1=0.220
B1=135.0
t1=140.0
v1=A1*t1-B1/t1

#result
print('(a) Fluid X\n v = %.2f centipoises'%v)
print('\n(b)Fluid Y\n v = %.1f centipoises'%v1)

(a) Fluid X
v = 10.31 centipoises

(b)Fluid Y
v = 29.8 centipoises

### Example 7.6, Page Number: 441

In :
import math

#variable declaration
t=12.0                    # time interval of falling ball in sec
Rsb=7.0                   # Specific gravity of ball
Rsf=1.12                  # Specific gravity of fluid
B=1.5                     # Ball constant in centipoises

#calculation
mu=t*(Rsb-Rsf)*B

#result
print('mu= %.2f centipoises = %d centipoises(approx)'%(mu,math.ceil(mu)))

mu= 105.84 centipoises = 106 centipoises(approx)

### Example 7.7, Page Number: 441

In :
#(a)

#variable declaration
B=45.0             # dry bulb temperature
W=25.0             # wet bulb temperature

#result
print('\n(b)\nPsychromatic differential : %d°C'%(B-W))
print('\n Relative humidity is 80%% corresponding to')
print(' \ntemperature 45°C  and psychromatic differential 20°C')

#(b)

#variable declaration
B1=30.0               # dry bulb temperature
W1=27.0               # wet bulb temperature

#result
print('\n(b)\nPsychromatic differential : %d°C'%(B1-W1))
print('\n Relative humidity is 80%% corresponding to')
print(' \ntemperature 30°C  and psychromatic differential 3°C')

(b)
Psychromatic differential : 20°C

Relative humidity is 80%% corresponding to

temperature 45°C  and psychromatic differential 20°C

(b)
Psychromatic differential : 3°C

Relative humidity is 80%% corresponding to

temperature 30°C  and psychromatic differential 3°C

### Example 7.8, Page Number: 441

In :
#variable declaration
D=80.0                # intersection point of DB temperature
W=66.5                # intersection point of WB temperature

#Result

#(a)
print('(a)\nThe intersection point of DB temperature 80°F and WB temperature 66.5°F')
print(' \nlines on the relative humidity curve for 50%.\n RH = 50%')

#(b)
print('\n(b)\nFrom the point of intersection of the dry and wet bulb curves, move left')
print(' \nhorizontally to the dew point temperature curve where it meets at 60°F')
print('\nDew Point = 60°F')

#(c)
print('\n(c)\nFrom the point of intersection of the dry and wet bulb curves,')
print('\nhorizontally to the right to the moisture content plot where it meets at 76.')
print('\nMoisture Content : 76 grains of water per pound of dry air.')

(a)
The intersection point of DB temperature 80°F and WB temperature 66.5°F

lines on the relative humidity curve for 50%.
RH = 50%

(b)
From the point of intersection of the dry and wet bulb curves, move left

horizontally to the dew point temperature curve where it meets at 60°F

Dew Point = 60°F

(c)
From the point of intersection of the dry and wet bulb curves,

horizontally to the right to the moisture content plot where it meets at 76.

Moisture Content : 76 grains of water per pound of dry air.

### Example 7.9, Page Number: 442

In :
#variable declaration
wt_vap=500.0           # Amount of water vapour present
wt_vap_to_sat=1500.0   # Amount of water vapour added to saturate

#calculation
total=wt_vap+wt_vap_to_sat
Rh=(wt_vap/total)*100

#result
print('RH = %d%%'%Rh)

RH = 25%

### Example 7.10, Page Number: 442

In :
#variable declaration
pv=30.0             # partial pressure of water vapour
ps=60.0             # Saturation partial pressure

#calculations
Rh=(pv/ps)*100

#Result
print('%%RH = %d%%'%Rh)

%RH = 50%

### Example 7.11, Page Number: 442

In :
#variable declaration
i1=250.0                  # ionazation current
i2=350.0                  # ionazation current

#calculation
m=(i2-i1)*100/i1

#result
print('%% increase in moisture content = %d%%'%m)

% increase in moisture content = 40%

### Example 7.12, Page Number: 443

In :
#variable declaraton
i2=150.0    # wet weight
i1=125.0    # dry weight

#calculation
m=(i2-i1)*100/i1

#result
print('Moisture percentage = %d%%'%m)

Moisture percentage = 20%