Sizing a counterflow air-to-air heat exchanger 1

[dextermech]

lease help. I have 100 SCFM of 250F air and want to transfer all of it's heat (down to ambient = 70F) to a separate 100 SCFM airflow. How do I calculate the necessary surface area?

Also, is a shell and tube design or a plate design best for air? Thanks for any help.

 

[dextermech]

Yank It confused me too at first. I never did an HX before.