Chapter 6 - Flow processes : First law analysis

Example 1 - Pg 76

In [1]:
#Calculate the power output of the machine
#initialization of varaibles
import math
u1=1111.9 #Btu/lb
P1=170. #psia
v1=2.675 #cu ft/lb
v2=100.9 #cu ft/lb
z1=10. #ft
V1=6000./60. #ft/sec
Q=-1000.
u2=914.6 #B/lb
P2=3. #psia
V2=300. #ft/sec
rate=2500.  #lb/hr
#calculations
Wx=rate*(u1-u2 + (P1*v1-P2*v2)*144/778 +(V1*V1 -V2*V2)/(2*32.2*778.) +z1/778. +Q/rate)
f=3.92*math.pow(10,-4)
power = Wx*f
#results
print '%s %d %s' %("Power output of turbine = ",Wx,"B/hr")
print '%s %.1f %s' %("\n Power output in hp =",power,"hp")

Power output of turbine =  558647 B/hr

 Power output in hp = 219.0 hp

Example 2 - Pg 78

In [2]:
#calculate the flow rate
#initialization of varaibles
w1=500.              #lb/min
h1=132.9             #lb/min
h2=1150.             #B/lb
h3=180.              #B/lb
#calculations
w2=(w1*h1-w1*h3)/(h3-h2)
#results
print '%s %.1f %s' %("Flow rate =",w2,"lb/min")

Flow rate = 24.3 lb/min

Example 3 - Pg 79

In [3]:
#Calculate the average velocity and rate of flow
#initialization of varaibles
import math
v2=5.434        #cu ft/lb
v1=4.937        #cu ft/lb
h1=1227.6
h2=1223.9
A1=math.pi/144
#calculations
Vratio=v2/v1
V1=math.sqrt(64.4*(h1-h2)*778./(Vratio*Vratio -1))
V2=V1*Vratio
w=A1*V1/v1
#results
print '%s %d %s' %("Average velocity at 1 =",V1,"fps")
print '%s %d %s' %("\n Average velocity at 2 =",V2,"fps")
print '%s %.2f %s' %("\n Rate of flow = ",w,"lb/sec")

Average velocity at 1 = 936 fps

 Average velocity at 2 = 1030 fps

 Rate of flow =  4.14 lb/sec