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Workshop/5 min exploration

Inside a refrigerator

Why is the back warm when the inside is cold?

A refrigerator moves heat from its food compartment into the room. An electric compressor keeps refrigerant circulating through two heat exchangers and a narrow expansion tube. Follow the white marker around the loop, then switch the compressor off to see which part of the process requires electrical work.

Explore the model and follow its moving parts.

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The room receives the heat removed from the fridge, plus energy supplied to the compressor.

During steady operation, what heat does the condenser release to the room?

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How the parts work together

  1. Add work at the compressor

    Start at the compressor. It takes in low-pressure vapour and pushes it out at higher pressure and temperature. Electrical work makes this sustained circulation possible. The marker follows one parcel; the other components keep operating at the same time.

  2. Release heat into the room

    Follow the orange high-pressure line into the condenser. Heat leaves for the surrounding air, and the refrigerant changes from vapour to liquid. This is why the outside heat exchanger feels warm during operation.

  3. Drop the pressure

    The high-pressure liquid passes through the narrow capillary tube. Its pressure falls, and part of it flashes into vapour. Follow the change from the orange high-pressure side to the blue low-pressure side.

  4. Take heat from the inside

    The cold mixture enters the evaporator. As its liquid evaporates, it absorbs heat from the compartment. Vapour returns to the compressor. Now switch the compressor off: the model stops its driven circulation and active heat-transfer arrows.

The main parts

Compressor
An electric motor drives the pump inside this sealed housing. It draws in low-pressure vapour and discharges higher-pressure, hotter vapour. It supplies work to the cooling cycle.
Condenser · heat out
The outside heat exchanger transfers heat from the refrigerant to the room. As high-pressure refrigerant gives up heat, it condenses from vapour into liquid. It releases both the absorbed interior heat and the compressor's added energy.
Capillary tube · pressure drop
This narrow tube restricts the flow between the high- and low-pressure sides. Across it the pressure drops and some liquid flashes into vapour. The resulting cold liquid-vapour mixture enters the evaporator. The coil is enlarged here so it can be inspected.
Evaporator · heat in
Inside the cabinet, low-pressure refrigerant absorbs heat as the remaining liquid evaporates. The refrigerant leaves as vapour and returns to the compressor. Interior air and the refrigerant travel in separate spaces.
Insulated cabinet
Insulation slows heat entering from the room. The cutaway opens the front and removes a side panel to reveal the cooling circuit; it is an inspection view, not a simulation of leaving the door open.

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