Gekko和CoolProp

Question

我使用GEKKO和CoolProp来模拟热系统。当试图在模型方程中使用CoolProp函数(如下面所示的等熵展开所示)时，我得到了一个关于变量类型的错误消息：“必须是实数，而不是GKVariable”。有人能帮我解决这个问题吗？

from gekko import GEKKO
import CoolProp.CoolProp as CP 
#
p1 = 2e5
T1 = 300.0 + 273.15
p2 = 1e5
eta = 0.80
fluid = 'H2O'
#
h1 = CP.PropsSI('H','T',T1,'P',p1,fluid)
s1 = CP.PropsSI('S','T',T1,'P',p1,fluid)
#
m = GEKKO()
h2 = m.Var()
h2s = m.Var()
T2 = m.Var()
#
m.Equation(eta * (h1 - h2) - (h1 - h2s) == 0)
m.Equation(h2s - CP.PropsSI('H','S',s1,'P',p2,fluid) == 0)
m.Equation(h2 - CP.PropsSI('H','T',T2,'P',p2,fluid) == 0)
#
m.options.IMODE = 1  #Steady state
m.options.SOLVER = 3 # solver (IPOPT) 
m.solve(disp=False)
#
print(T2.value[0])

提前谢谢。

Answer 1

Gekko需要有CoolProp方程来执行自动微分。如果它没有等式，那么您可以使用cspline (三次样条文档)。

from gekko import GEKKO
import CoolProp.CoolProp as CP 
import numpy as np
#
p1 = 2e5
T1 = 300.0 + 273.15
p2 = 1e5
eta = 0.80
fluid = 'H2O'
# constants
h1 = CP.PropsSI('H','T',T1,'P',p1,fluid)
s1 = CP.PropsSI('S','T',T1,'P',p1,fluid)
c2 = CP.PropsSI('H','S',s1,'P',p2,fluid)
# gekko model
m = GEKKO(remote=False)
h2 = m.Var()
h2s = m.Var()
T2 = m.Var()
# build cubic spline
n = 100
T = np.linspace(373,1000,100)
h = [CP.PropsSI('H','T',Ti,'P',p1,fluid) for Ti in T]
m.cspline(T2,h2,T,h)
#
m.Equation(eta * (h1 - h2) - (h1 - h2s) == 0)
m.Equation(h2s - c2 == 0)
#
m.options.IMODE = 1  #Steady state
m.options.SOLVER = 3 # solver (IPOPT) 
m.solve(disp=False)
#
print(T2.value[0])

这就产生了解决办法：

T2 = 468.52459939