Dear Anand dev

Desalination has now become one of the major water treatment processes in several countries around the world where shortage of water is a serious problem. Energy consumption is a vital economic factor in selecting the type of desalination processes because current desalination processes require large amount of energy which is costly. Multi-effect desalination system with thermal vapor compression (MED-TVC) is particularly more attractive than other thermal desalination systems due to its low energ

Energy level= Sigma [M * (H_Stream- H_Cooling Water)]

and finally, 

PR= (Net Distillate mass flow rate) / (  Energy level / 2336 Kj). 

In Ejector system the pressureof stam called motive steam, is fed into the thermo compressor through a sonic nozzle. Its expansion will allow low pressure steam from a cell of the evaporator to be sucked out. Both steams will be mixed in the thermo compressor body. The mixture is then compressed to the pressure of the first bundle through a shock wave. The latent heat of the sucked vapour is thus recycled in the evaporator and is again available for desalination, leading to energy savings.

The performance of a thermo compressor is expressed by the mass of sucked steam (in kg) per kg of motive steam. This ratio is usually called w. The higher the motive steam pressure, the greater the w value (for a given temperature difference between the extraction of the sucked steam and the condensation temperature of first cell). On the other hand, for a given motive steam pressure, the higher the temperature difference, the lower the value of w.Very high gain output ratios (GOR) can be obtained with MED -TVC units.

Please find attached related link

Regards,

Prem Baboo

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwip0Yi7p8LJAhWUj44KHUMNB7sQFggvMAM&url=http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F254225044_Study_of_steam_parameters_on_the_performance_of_a_TVC-MED_desalination_plant&usg=AFQjCNEQxM-4WmjDEpreNKIwjXm8A1rMwA&sig2=qqBOdh3awhaL0AqEL1gk7g

You surely need to consider energy input in the TVC unit , which should be the major energy input into the whole system if not all. You will need to consider other energy input into the system such as preheater if the system has. Then you can get the PR by dividing the total distillate flow in ton per hour by total energy input in equivalent ton steam per hour.

i think this reference will be useful

useful link:

https://dspace.mit.edu/openaccess-disseminate/1721.1/89068

you need to divide the total mass flow rate of permeate by the mass flow rate of motive steam entering to the TVC.