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📘 Stand beside the warm back panel

At 2 a.m., put your hand near the refrigerator’s back panel. It is warm because the appliance is sending heat into the room—the first clue that cooling is a heat-transfer job, not cold creation.

4
lessons
~20 min
to learn
Adults
level
Start the course →

What you’ll learn

  1. The cold box is not making coldUnderstand that a refrigerator transfers heat from its interior to the room by spending electrical work.Heat, work, and a circulating refrigerant form a heat-pump system.
  2. Four moves around one loopIdentify the evaporator, compressor, condenser, and expansion device and explain their order.Four components coordinate phase and pressure changes in a sealed loop.
  3. The pressure drop is the hingeConnect pressure to boiling temperature and see why the expansion device enables the cold side.Pressure zones give the refrigerant two different useful boiling and condensing conditions.
  4. Where the energy goesUse energy conservation and COP to reason about refrigerator performance in a real kitchen.The room receives both the collected heat and the compressor's work.

Questions this course answers

Which component absorbs heat from the refrigerator compartment?

The low-pressure refrigerant boils in the evaporator while absorbing heat from the cabinet.

Why must the refrigerant be hotter than the room in the condenser?

Heat transfer to the room requires the condenser refrigerant to be at a higher temperature.

What does the expansion device primarily create?

The restriction meters flow and drops the refrigerant pressure, lowering its temperature.

If a refrigerator removes 100 units of heat and uses 30 units of work, how much heat reaches the room?

Energy conservation gives Qhot = Qcold + W, so 100 + 30 = 130 units.

What does a refrigerator COP of about 3.3 mean in the example?

COPref is useful cooling divided by work: 100/30 is about 3.3.

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