Plot Pressure- enthalpy (P-H) diagram

Dear All,

How can I plot a PH (pressue- enthalpy) diagram using coolprop library through matlab for 'R134a'?

Regards

[Sulaymon Eshkabilov]

Have checked these links:

http://ibell.pythonanywhere.com/

http://www.coolprop.org/coolprop/wrappers/MATLAB/index.html#matlab

Answer 1

[Karan Singh]

Hi Hussein, as you would have tried and seen the “CoolProp” library. First install this library.

So we can try via python in MATLAB. Here are the detailed steps for the same.

1. Install python from Welcome to Python.org according to your os I have used the Python 3.9.1.
2. Open MATLAB and add python by using the following commands:

 pyversion C:\Users\<user>\AppData\Local\Programs\Python\Python39\python.exe 

Check the Python version to ensure it's set up correctly.

pyversion 

Now, Python is integrated into your MATLAB environment. Proceed to install "CoolProp."

1. To install "CoolProp," execute the following MATLAB command:

 [v,e]=pyversion; system([e, ' -m pip install --user -U CoolProp']) 

2. Now that "CoolProp" is installed, you can set the parameter values and write the rest of the code.

 % Define pressure and enthalpy ranges 
 pressure = linspace(0, 2e6, 100); % Pressure range in Pa 
 enthalpy = linspace(0, 3000e3, 100); % Enthalpy range in J/kg 
 
 % Calculate specific volume 
 v = zeros(length(pressure), length(enthalpy)); 
 for i = 1:length(pressure) 
     for j = 1:length(enthalpy) 
         v(i, j) = CoolProp.PropsSI('D', 'P', pressure(i), 'H', enthalpy(j), 'R134a'); 
     end 
 end 
 
 % Plot the PH diagram 
 figure; 
 contourf(enthalpy, pressure, v, 'LineStyle', 'none'); 
 colorbar; 
 xlabel('Enthalpy (J/kg)'); 
 ylabel('Pressure (Pa)'); 
 title('R134a Pressure-Enthalpy (PH) Diagram'); 

This would plot the required result, please note that using "CoolProp" through the Python interface in MATLAB may have some performance implications due to the inter-language communication overhead.