The single hose units work. They have a lot of downsides though. They are heavy, loud and require a supply of fresh air. That means that your either do not block the window completely and draw hot air in, thus reducing the available cooling capacity of the unit, or seal the window and the unit will create low pressure area in your home and draw the air from elsehwere (via other leaking doors, windows or even bathroom fans - which can be a bit smelly).

tl;dr If you are considering a portable AC unit, try to get a dual hose one, or save for a mini/multi split.