The best reference in the internet that I came across is this site:

http://www.sankey-diagrams.com/sankey-diagram-software/

The wikipedia article also has some good references.

https://en.wikipedia.org/wiki/Sankey_diagram

Depending of the quality and complexity of the desired diagram, I suggest you to build your personal template in MS Visio.

Dear Laxman,

one program I know of is e!Sankey, which is however proprietary.

Best regards

Eric

Thank you for your suggestions Eric C Okonkwo , Rafael Nogueira Nakashima

I suggest SankeyMATIC. It's easy to use and for free.

http://sankeymatic.com/

Hello

I like this book:

The Exergy Method of Thermal Plant Analysis by T.J. Kotas

This an amazin book explaining how use exergy balance, incluiding Grassmann Diagram, the link below is from google book, there is an example. After you have you exergy flows and exergy losses, you can use http://sankeymatic.com.

https://books.google.com.mx/books?id=-QLLBAAAQBAJ&pg=PA84&dq=Grassmann+Diagram+exergy&hl=es-419&sa=X&ved=0ahUKEwjTza2QqMnfAhUEX60KHdNMCU8Q6AEIMTAB#v=onepage&q=Grassmann%20Diagram%20exergy&f=false

Also if you want to about exergy destruction and exergy losses you can see my other answers:

https://www.researchgate.net/post/Exergy_loss_and_Entropy_production_are_equivalent_termsCan_they_be_used_interchangeably2

https://www.researchgate.net/post/what_does_it_mean_by_exergy_destruction

This web page may be helpful.

http://sankeymatic.com

I also recommend taking a look at https://www.ifu.com/en/e-sankey/

It is able to visualize complex processes and has a feature to have a link with MS Excell - that enables to redraw the diagram via a single click.