Yeah I agree, Only trouble "most" physics relates to and Ideal world set of figures where as we live/operate in a varying world of physics So although we could both have the same fridge we both could end up with a different set results,No. If the fridge is stabilized (steady state) adding a bottle of water etc will increase the cooling load by the amount I calculated. Obviously you have the existing cooling load + 22 watt-hours. This energy usage (about 8 watt hours of electricity) will be spread out over an hour or two. It is a specific and easily calculated value. I work with this type of stuff for a living, this is an engineers bread and butter really.
The whole purpose of this exercise in physics is to describe/define the size of various factors on a fridges cooling load. As described above air loss is a minor impact on cooling load for fridges that are not opened and closed constantly.
A fridge is system, in physics energy in minus stored energy must equal energy out.
One thing for sure although these fridges use less power than our domestic freezers they appear to have a lot more cooling power IE I put a drinking glass of water in there that measured 5" by 2.5" straight out of the water tap and it froze it in about 1 hour 50 minutes and it will make 2.5"square X 1/2" think Ice blocks in about an hour +/-