Evaporator Size

Go buy a 2-ton air conditioner somewhere. Remove the sheet metal and then count/measure the evaporator coil and condenser coil components. This process is called "reverse engineering."

What size air conditioner?

Look at hm904's numerous other posts, and you will see where this size estimate came from.

It is depend on the capacity of AC in Tons. There is no any general term releted to it. You need to know following things to design your custom made condenser, inlet temperature of fluid to condenser, outlet temperature of fluid, mass of fluid, coefficient of specific heat at contant pressuer. Then you can calculate amount of heat need to be removed from the fluid and based on that you can calculate area of condenser.