How to calculate the performance ratio (PR) for MED-TVC desalination

Dear Members, I want to know how I can check/calculate the performance ratio for MED-TVC desalination process if I have the PFD (process flow diagram) of desalination plant? Is there any standard process or charts available for this? Do I need to consider the energy of steam entered to TVC also? I would be very grateful if I can see a sample calculation for any MED-TVC desalination plant. Thank you in advance.