Hi Reza How are you? As ...

Hi Reza
How are you?
As you know, general definition of performance ratio is kg of water produced per 2326 kJ of heat consumed. For each project client, supplier and engineers, have to agree which water and steam streams are considered in the calculation. I am familiar with your current project so this is my advice based on my previous experiences and current research.

You need to calculate energy level of steam enterered desaliantion for TVC and ejectors. You have mass flow rates and temperatures for steam streams in PFD and only you have to caculate enthalpy change. Entalpy change is difference between entalpy of cooling water (condencer inlet) and entalpy of steam streams. We can not decrease entalpy of steam lower than reference entalpy which is cooling water entalpy, that's why.

Energy level= Sigma [M * (H_Stream- H_Cooling Water)]
and finally,
PR= (Net Distillate mass flow rate) / ( Energy level / 2336 Kj).

You have to consider ejector consumption and condensate in first effect in your calculation. To put it another way, desalaintion as a black box in your calculation. I am interested in your current project and don't hesitate to ask if you have any qestion.