EES connector is a tools developed by the SERG research group of the University of Florence for launching EES calculation and retrieving results from python.

The beta version can be downloaded using PIP:

pip install EES_connector

From version 1.0.0 a major improvement has been made to the code. For compatibility the previous class (EESConnector) is still usable (you can find the old documentation here) but it will not be maintained

Once the installation has been completed the user can import the tool and initialize the connector itself.

from EESConnect import EESConnectorPlus

with EESConnectorPlus() as ees:

    # insert your code here

Two important aspects to keep in mind for the initialization:

• Please use the with statement during the initialization as shown above

• A file-dialog will appear the first time that the connector is imported asking the user to select the EES executable path (usually it's "C:\EES32\ees.exe"). Once the executable path has been selected, the program keep it in memory in order to avoid new appearance of the file-dialog. The stored executable can be modified calling the following function:

from EESConnect import EESConnectorPlus

EESConnectorPlus.modify_ees_executable_path()

from EESConnect import EESConnectorPlus
from tkinter import filedialog
import tkinter as tk

#select the ees file path
root = tk.Tk()
root.withdraw()
ees_file_path = filedialog.askopenfilename()

with EESConnectorPlus() as ees:
    
    ees.ees_file_path = ees_file_path
    params = ees.calculate({
        
        "input": {"fluid$": "air_ha", "T": 300, "P": 1013.25}, 
        "output": {"h": None, "s": None}
    
    })
    print(params)

Calls with multiple parameters are possible as follows:

from EESConnect import EESConnectorPlus
from tkinter import filedialog
import tkinter as tk

#select the ees file path
root = tk.Tk()
root.withdraw()
ees_file_path = filedialog.askopenfilename()

params = {
    
    "input": {
        
        "fluid$": ["air_ha", "R22", "R236fa", "R134a"], 
        "T": [300, 300, 300, 300], 
        "P": [1013.25, 1013.25, 1013.25, 1013.25]
    
    }, 
    "output": {"h": None, "s": None}

}

with EESConnectorPlus() as ees:
    
    ees.ees_file_path = ees_file_path
    params = ees.calculate(params)
    print(params)

Please notice that the EES file has to be configured properly in order to work.
Here's an example, that works with the python code described above:

$UnitSystem SI K kPa kJ 
h=enthalpy(fluid$; T=T; P=P)
s=entropy(fluid$; T=T; P=P)

An explanation on how to set EES properly can be found here. In addition here's some important things had to be noted:

• The keys of the "input" and "output" dictionaries must share the same name, in the EES code, with the variable that they refer in
• The values identified in the "input" dictionary must not be defined in the code (e.g. do not write "T=300" in the code above)
• The code must work if the variable identified in the "input" dictionary are manually set in the code

Multiple options could be set in initializing the calculator:

from EESConnect import EESConnectorPlus

with EESConnectorPlus(ees_decimal_separator=".", display_progress_bar=True, timeout=10) as ees:

    # insert your code here

• "ees_decimal_separator" allows you to set the decimal separator in order to match the one required by your EES file. The default is a comma (",")
• "display_progress_bar" shows a bar describing the progress of the calculation
• "timeout" set a timeout limit for the calculation (value to be set in seconds)

You export the results of your calculation to excel using Pandas with the following code:

with EESConnectorPlus(timeout=10, display_progress_bar=True) as ees:

    # Calculate
    params = ees.calculate(params)
    
    # Export results
    ees.export_to_excel(params=params, excel_path=os.path.join(base_folder, "results.xlsx"))

EESConnectorPlus works by executing EES Macros. The behaviour of the macro can be modified by the user to perform more complex operation (the most typical usage is to perform optimization in EES). This can be done by modifying the attribute "ees.calculation_instruction". For example, for performing the optimization, you can use the Minimize Macro instruction as shown below:

from EESConnect import EESConnectorPlus

with EESConnectorPlus() as ees:

    ees.ees_file_path = os.path.join(base_folder, "optimization_trial.EES")
    
    # This code can be used to minimize y_max by changing x_max
    ees.calculation_instruction = "Minimize y_max  x_max  /Method=Conjugate  /RelTol=1e-6  /MaxIt=500"

    params = ees.calculate(params)

by default ees.calculation_instruction = "Solve".
In general the MACRO that will be run by EES will be the following:

ONERROR GOTO 10
DIR$=GetDirectory$
Open 'ees_program.ees'
Import 'ees_input.dat' f$ {{ Input Parameters }}

{{ calculation_instruction }}

Export f$ {{ Output Parameters }}
10:quit

You can find some example code in this folder

-------------------------- !!! THIS IS A BETA VERSION !!! --------------------------

please report any bug or problems in the installation to pietro.ungar@unifi.it
for further information visit: https://tinyurl.com/SERG-3ETool