Issue457 expansion valves tank

Created by: MirkoEngelpracht

Good evening everyone,

this issue should have been solved now and can be reviewed. I assume that I'll need to change a few things as soon as the refrigerant library developed at #408 (closed) is merged into the development branch. However, it may be reasonable to request a first review (perhaps from @cvering or @tstorek because they are my supervisors). Thus, I may benefit from the review and avoid mistakes from the beginning in further issues I'm currently working on :)