"EXAMPLE: Brayton cycle with regeneration
 
Reconsider the air-standard Brayton cycle from the last example. The following conditions still apply: compressor inlet: 100 kPa, 300 K; turbine inlet: 1 MPa, 1300 K. Now add an ideal regenerator to the system.
 
(a)	Find the new heat transfer rate (per unit mass flow rate) into the high pressure heat exchanger and the new cycle efficiency.
(b)	Find the rate of entropy generation for the regenerator.
(c)	Repeat (a) and (b) if eta_regen = 0.85."
 
T_1 = 300 [K]
P_1 = 100 [kPa]
 
P_3 = 1000 [kPa]
T_3 = 1300 [K]
 
"CoE, (1)-->(2)"
w_12_in = h_2 - h_1
h_1 = enthalpy(Air,T=T_1)
s_1 = entropy(Air,T=T_1,P=P_1)
P_2 = P_3
s_2 = s_1
h_2 = enthalpy(Air,P=P_2,s=s_2)
T_2 = temperature(Air,P=P_2,s=s_2)
 
 
"CoE, (x)-->(3)"
q_x3_in = h_3 - h_x 
h_x = enthalpy(Air,T=T_x)
T_x = T_4
 
"CoE, (3)-->(4)"
w_34_out = h_3 - h_4
h_3 = enthalpy(Air,T=T_3)
s_3 = entropy(Air,T=T_3,P=P_3)
P_4 = P_1
s_4 = s_3
h_4 = enthalpy(Air,P=P_4,s=s_4)
T_4 = temperature(Air,P=P_4,s=s_4)
 
 
"CoE, (5)-->(1)"
q_51_out = h_5 - h_1
h_5 = enthalpy(Air,T=T_5)
T_5 = T_2
 
"Cycle effficiency"
eta = (w_34_out-w_12_in)/q_x3_in