In general, a kitchen refrigerator is essentially a heat pump. The vapor compression cycle creates a temperature difference, and the insulated compartment stays cold. But how can I determine the heat output of such a heat pump or its COP?
The user manuals only give the average energy consumption per day, but because of the insulation the compressor doesn't have to run all the time, it just turns on when the temperature inside exceeds some threshold, and stops when it reaches another threshold.
As a side question, is a kitchen refrigerator a viable option for low energy cooling? For example, if I have a device with a TDP of less than 300 watts and it needs sub-ambient temperatures, can I just put it in the refrigerator?