Chapter 16 - Gas Cycles

Example 1a - Pg 279

In [1]:
#calculate the efficiency and work done per pound of fluid
#initialization of varaibles
import math
Pb=75. #psia
Pc=15. #psia
k=1.4
Td=550. #R
Tb=1700.  #R
cp=0.24
#calculations
print '%s' %("Gas law solution")
Pratio=Pb/Pc
Ta=Td*math.pow((Pratio),((k-1)/k))
Tc=Tb/math.pow((Pratio),((k-1)/k))
Q1=cp*(Tb-Ta)
Q2=cp*(Tc-Td)
Wnet=Q1-Q2
eta=Wnet/Q1
eta2=1-Td/Ta
#results
print '%s %.3f' %("Efficiency in 1= ",eta)
print '%s %.2f' %("\n Efficiency in 2 = ",eta2)
print '%s %d %s' %("\n Work per pound of fluid =",Wnet,"B/lb")

Gas law solution
Efficiency in 1=  0.369

 Efficiency in 2 =  0.37

 Work per pound of fluid = 73 B/lb

Example 1b - Pg 280

In [2]:
#calculate the efficiency and work done per pound of fluid
#initialization of variables
import math
Pb=75. #psia
Pc=15. #psia
k=1.4
Td=550. #R
Tb=1700.  #R
cp=0.24
#calculations
Prd=1.4779
hd=131.46 #B/lb
Prb=90.95
hb=422.59 #B/lb
Pratio=Pb/Pc
Pra=Pratio*(Prd)
Ta=868 #R
ha=208.41
Prc=Prb/Pratio
Tc=1113 #R
hc=269.27
Q1=hb-ha
Q2=hc-hd
Wnet=Q1-Q2
eta=Wnet/Q1
#results
print '%s %.3f' %("Efficiency = ",eta)
print '%s %.2f %s' %("\n Work per pound of fluid =",Wnet,"B/lb")

Efficiency =  0.357

 Work per pound of fluid = 76.37 B/lb

Example 2 - Pg 282

In [3]:
#Calculate the work done and efficiency of the process
#initialization of varaibles
e=0.75
Ta=870.  #R
Tc=1075. #R
cp=0.24
Td=550.  #R
Tb=1700. #R
#calculations
Tadash=e*(Tc-Ta) +Ta
Tcdash=Tc+Ta-Tadash
Q1=cp*(Tb-Tadash)
Q2=cp*(Tcdash-Td)
Wnet=Q1-Q2
eta=Wnet/Q1
#results
print '%s %d %s' %("Net work done =",Wnet,"B/lb")
print '%s %.2f' %("\n efficiency = ",eta)

Net work done = 73 B/lb

 efficiency =  0.45