In the Phanteks specs sheets for liquid cooling, the
120mm column refers to radiators having such width but varied lengths based on number of 120mm fans (e.g., 120mm (1-fan), 240mm (2-fan), 360mm (3-fan), 480mm (4-fan)...). On the other hand, the
140mm column refers to radiators having such width but varied lengths based on number of 140mm fans (e.g., 140mm (1-fan), 280mm (2-fan), 420mm (3-fan)...).
In your case, the Corsair H100i v2 is indeed a "240mm" radiator, which means it uses two 120mm fans. But note that the actual dimension of the radiator is not exactly 240mm in length. The 240mm simply means nominal length - not actual dimensional length. This is important as some case specifically states the actual length of radiators that can fit in their mounting locations.
For the Enthoo Evolv being fitted with the Corsair H100i v2, you won't have any problems with such.
In fact you have two options to choose from where you can mount the 240mm radiator in the Evolv case: Top (Supports up to 360) or Front (Supports up to 360).
Sample build of a Corsair H100i v2 fitted on
top of a Phanteks Evolv case:
https://pcpartpicker.com/b/Hd9J7P
Sample build of a Corsair H100i v2 fitted at the
front of a Phanteks Evolv case:
https://pcpartpicker.com/b/ZRV6Mp