Chapter 15 - Vapor Cycles : More Efficient Cycles

Example 1 - Pg 243

In [1]:
#calculate the improvement in efficiency
#initialization of varaibles
e=0.85
print '%s' %("From Mollier chart and table 3,")
h1=1474.5 #B/lb
s1=1.5603 #B/lb R
h2s=1277.5 #B/lb
#calculations
h2=h1-e*(h1-h2s)
h3=1522.4 #B/lb
h4s=948 #B/lb
h4=h3-e*(h3-h4s)
h5=47.6 #B/lb
h6=53.5 #B/lb
h7s=840 #B/lb
h7=h1-e*(h1-h7s)
h8=1493.2 #B/lb
h9s=866 #B/lb
h9=h8-e*(h8-h9s)
h11=51.5 #B/lb
eta1=0.401
eta2=0.375
eta3=0.366
IE1=(eta1-eta2)/eta2
IE2=(eta1-eta3)/eta3
#results
print '%s %.1f %s' %("Improvement in efficiency =",IE1*100,"percent")
print '%s %.1f %s' %("\nImprovement in efficiency in case 2=",IE2*100,"percent")

From Mollier chart and table 3,
Improvement in efficiency = 6.9 percent

Improvement in efficiency in case 2= 9.6 percent

Example 2a - Pg 257

In [2]:
#Calculate the fraction of energy supplied 
#initialization of varaibles
print '%s' %("From mollier chart and table 3,")
h1=1371. #B/lb
h2s=1149. #B/lb
h3=118. #B/lb
e=0.9
print '%s' %("Neglecting pump work,")
Q1=h1-h3
W=156. #B/lb
eta1=W/Q1
Q=h1-W-h3
UE=W+e*Q
fraction = UE/Q1
#results
print '%s %.2f' %("Fraction supplied = ",fraction)

From mollier chart and table 3,
Neglecting pump work,
Fraction supplied =  0.91

Example 2b - Pg 258

In [3]:
#Calculate the fraction of energy supplied 
#initialization of varaibles
print '%s' %("From mollier chart and table 3,")
h1=1371. #B/lb
h2s=1149. #B/lb
h3=118. #B/lb
e=0.23
e2=0.9
print '%s' %("Neglecting pump work,")
Q1=h1-h3
W=156. #B/lb
eta1=W/Q1
Q=h1-W-h3
We=W/e
UE=We+Q
UE1=W+e2*Q
Q2=Q+We
fraction = UE1/UE
#results
print '%s %.2f' %("Fraction supplied = ",fraction)

From mollier chart and table 3,
Neglecting pump work,
Fraction supplied =  0.64