I'm guessing you are thinking of getting a small bar fridge, then turing it over so the opening points to the ceiling?
Honestly I am not sure that would work at all. You would need to chill the keg for at least three hours in a completely sealed fridge and with the door open it might take much longer or maybe not even work at all.
I see two options which you could do. The first is if you are only interested in cooling and chilling for stints at a time. The second is what I would personally do.
- Insulate a 5 gallon bucket with reflective insulation or styrofoam and fill it with water and salt. Put the keg in the bucket. The salt will lower the temperature of the water. You can then add in ice to further chill your keg.
- Buy a small keg i.e 1 gallon or 2.5 gallon keg. Fill the keg periodically from your main keg using a jumper connection and place the smaller keg in your fridge. The 1 gallon can sit upright like normal and the 2.5 gallon keg can have its dip tube bent so the keg can rest horizontally in your fridge.
Warning: With repeated heating and cooling of your beer you can also develop permenant chill haze.
Chill haze is a haze that forms when beer is cooled and disappears
when the beer warms up. Repeated heating and cooling cycles can cause
chill haze to turn permanent. Chill haze is formed when proteins in
the beer bond weakly with polyphenols (also called tannins).
Here is a photo of a 2.5 gallon keg in someone's fridge: