Question

Which part of a refrigerator determines whether it is an open or closed system? how can you change the system from closed to open?

Answer 1

A refrigerator functions as a closed system when the door is shut, performing work to transfer heat from inside to the outside, adhering to the principles of thermodynamics. An open refrigerator system results when the door is opened, allowing exchange of energy and matter.

Step-by-step explanation:

The part of a refrigerator that determines whether it's an open or closed system is essentially the state of its door and the nature of its seal. A closed refrigerator system can be changed into an open system by opening the door, thus allowing exchange of both matter (in the form of air) and energy (heat) with the surroundings.

During the time periods in which the refrigerator door is closed, the system operates as a closed system where energy, in the form of work (W), is put into the system to remove heat from the inside to keep it cool. Specifically, the refrigerator uses energy to run a motor that moves a coolant through coils. The coolant, with a boiling point below the freezing point of water, extracts heat from the refrigerator at the evaporator thereby cooling the contents inside. The heat (Qc), which is absorbed from the cold interior, is then transferred outside as the compressed coolant passes through the condenser, releasing the heat (Qh) into the kitchen air.

Integration of these processes within the refrigerator abides by the laws of thermodynamics, particularly the First Law which relates to the conservation of energy. The total energy within the closed system remains constant, as it is transformed from electrical energy to mechanical energy and then to thermal energy, which is expelled to keep the contents cool.

Answer 2

A closed loop system is one where the ouput of the system is at least part of the input. In a refrigerator, the output of the cooling system (the cold air inside the refrigerator) is measured, and is fed back into the system to determine whether the system needs to continue cooling.

An example of a fridge that was an open loop system would be one that turns on and cools for 1 hour every 6 hours, regardless of internal temperature.