Final answer:
A refrigerator, when the door is closed, functions as a closed system. It can exchange energy (in the form of heat) but not matter with its surroundings, and work is done within the system to transfer heat, observing the conservation of energy principle.
Step-by-step explanation:
When identifying the system for a refrigerator and its immediate surroundings in terms of thermodynamics, it can be classified as a closed system. This characterization applies when considering the time periods in which the refrigerator door is closed. In such instances, a refrigerator can exchange energy with its surroundings (heat is removed from inside the refrigerator and expelled into the environment), but it does not exchange matter (no air or refrigerant escapes the sealed system).
Within the closed system of the refrigerator, heat transfer occurs as the refrigerator removes heat from its interior and expels it to the outside environment. Work is done by the refrigerator's compressor to facilitate this transfer of heat, and conservation of energy is observed as the total energy of the system and its surroundings remains constant. The energy used by the compressor to remove heat from inside the refrigerator is equal to the amount of heat released into the surroundings plus the energy lost due to inefficiencies in the system.