Hi all. We say (and what is true) that every change of phase occur with a change of heat (energy) which either comes into the material or comes out during change. So my question is maybe silli, but when we look at logp-h chart whe see, that durring expansion process some of a liquid refrigerant vaporize but enthalpy does not change... why? does it mean that liquid vaporised but took no energy? Why just after expansion process it normaly took energy (enthalpy rises) but at expansion proces it doesnot?

Thank you for answers
Marcin