Is it beneficial to point a fan at the intake of a portable air conditioner?
In addition to Henry's sensible comments (what a clever little boy!), I would like to add for general public consumption that the accordion duct/hose is only 3-4 ft long for a very good reason. After running the AC for a few hours, put your hand on the exhaust hose and you will feel lots of HEAT. Stringing a longer hose extension in the room would be like rigging a hot stove pipe extension...You need to place your so-called 'portable' AC as close to the venting window as possible, never more than 3 ft between unit and window including angles (which should be as minimal as possible). The less the accordion unfolds, the less heat the hose will emit on its way to the window outlet.

Calling these units 'portable' is kind of deceptive; you can't really move them around the room at will once installed without disturbing the exhaust system, especially if you put insulation around the exhaust at the window end. They should really be called just 'floor' models as opposed to 'window' models...