The project page on the Dyson Awards site manages to admit that it's based on old technology that Einstein thought up:

http://www.jamesdysonaward.org/projects/isobar/

I guess the proposed novelty is that it can be carried in a backpack and would be designed specifically for cooling vaccines. My reading of it suggests that there isn't much in the way of a practical model just yet (they show pictures of a prototype, but I wonder how long it has sustained cooling).