如何获得 GEKKO 化学流程图混合器对象来解决答案

【问题标题】：How do I get GEKKO chemical flowsheet mixer object to solve如何获得 GEKKO 化学流程图混合器对象来解决
【发布时间】：2022-10-18 09:59:07
【问题描述】：

我正在探索 Gekko 化学库和流程图实施。我定义了化合物丙烯、丙烷、丁烷和戊烷以及两种具有不同化合物分数和摩尔流速的物流。我想混合这些流并计算组合流的总摩尔流速和摩尔分数。

我得到的结果是： Mole fraction in blended stream is: [[0.25], [0.25], [0.25], [0.25]]。它似乎是出口流的初始化值。

我仔细阅读了这个 StackOverflow 链接 [这里] 1 没有成功。
示例代码在这里：

from gekko import GEKKO, chemical
import numpy as np

m = GEKKO()    #instantiate GEKKO object
f = chemical.Flowsheet(m,stream_level=0)  #instantiate flowsheet object
c = chemical.Properties(m)
c.compound('propylene')    #define compound 1
c.compound('propane')      #define compound 2
c.compound('butane')       #define compound 3
c.compound('pentane')      #define compound 4

s1=f.stream(fixed=True)    #define stream 1
s1.x=np.array([0.5,0.3,0.1,0.1])     #specify mole fraction of compound 1-4 for stream1
s1.ndot=10                 #specify molar flow rate of stream 1

s2=f.stream(fixed=True)    
s2.x=np.array([0.3,0.3,0.2,0.2])     #specify mole fraction of compound 1-4 for stream2
s2.ndot=20                 #specify molar flow rate of stream 2

outlet=f.stream(fixed=False) #define outlet stream that should be solved

mx = f.mixer(ni=2)        #mixer object with two inlet
#mx.inlet[0]=s1
#mx.inlet[1]=s2
f.connect(mx.inlet[0],s1)  #assign stream 1 to mixer inlet 1
f.connect(mx.inlet[1],s2)  #assign stream 2 to mixer inlet 2


mx.outlet=outlet  #connect mixer outlet to outlet stream obj
m.options.SOLVER=1
m.solve()

print('Mole fractions in blended stream is:',  mx.outlet.x)

【问题讨论】：

标签： python gekko

【解决方案1】：

使用以下命令初始化入口流的每个 x[i] 组件：

inlet1 = [0.5,0.3,0.1,0.1]
inlet2 = [0.3,0.3,0.2,0.2] 
for i in range(4):
    s1.x[i].value = inlet1[i]
    s2.x[i].value = inlet2[i]

使用连接函数左侧的stream 对象。连接函数将对象保留在左侧（第一个参数）并删除第二个对象引用（例如f.connect(keep,remove)）。出口流也需要一个连接：

f.connect(outlet,mx.outlet)

这是一个完整的脚本：

from gekko import GEKKO, chemical
import numpy as np

m = GEKKO()    #instantiate GEKKO object
f = chemical.Flowsheet(m,stream_level=0)  #instantiate flowsheet object
c = chemical.Properties(m)
c.compound('propylene')    #define compound 1
c.compound('propane')      #define compound 2
c.compound('butane')       #define compound 3
c.compound('pentane')      #define compound 4

s1=f.stream(fixed=True)    #define stream 1
inlet1 = [0.5,0.3,0.1,0.1]     #specify mole fraction of compound 1-4 for stream1
s1.ndot=10                 #specify molar flow rate of stream 1

s2=f.stream(fixed=True)    
inlet2 = [0.3,0.3,0.2,0.2]     #specify mole fraction of compound 1-4 for stream2
s2.ndot=20                 #specify molar flow rate of stream 2

for i in range(4):
    s1.x[i].value = inlet1[i]
    s2.x[i].value = inlet2[i]

outlet=f.stream(fixed=False) #define outlet stream that should be solved

mx = f.mixer(ni=2)        #mixer object with two inlet
#mx.inlet[0]=s1
#mx.inlet[1]=s2
f.connect(s1,mx.inlet[0])  #assign stream 1 to mixer inlet 1
f.connect(s2,mx.inlet[1])  #assign stream 2 to mixer inlet 2
f.connect(outlet,mx.outlet)
#mx.outlet=outlet  #connect mixer outlet to outlet stream obj
m.options.SOLVER=1
m.solve()

print('Mole fractions in blended stream is:',  outlet.x)
# Open run folder to see more detail from model and results
# m.open_folder()

这给出了混合解决方案：

 ----------------------------------------------
 Steady State Optimization with APOPT Solver
 ----------------------------------------------
 
 Iter    Objective  Convergence
    0  7.40741E-20  1.11111E+00
    1  1.08350E-35  1.15741E-01
    2  1.08350E-35  1.15741E-01
 Successful solution
 
 ---------------------------------------------------
 Solver         :  APOPT (v1.0)
 Solution time  :   1.279999999678694E-002 sec
 Objective      :   0.000000000000000E+000
 Successful solution
 ---------------------------------------------------
 
Mole fractions in blended stream is: [[0.4], [0.3], [0.15], [0.15]]

【讨论】：