if the capacity of a/c system is 400 cfm than what is the tr for the same?

Answer 1

Each 400 cfm should do between 1 to 1.25 tons (up to a total of about 200 TR). Going from one end to the other of this practical limit range you make a tradeoff between a fraction more for the up front total system hardware cost versus a little bit lower in electricity bill every month.

Answer 2

As a thumb rule 1Tr capacity air conditioner is capable to deliver 300 cfm air volume.