The Refrigerator

A refrigerator extracts heat from a system. Example: a kitchen refrigerator.

Again, to be useful, a refrigerator operates cyclically, with a certain amount of heat being extracted in every cycle.

Critical feature: two temperatures.

In a full cycle of a refrigerator, three things happen:

  1. Work is done to compress a gas
  2. Gas expands and removes heat Qc from the interior of the refrigerator
  3. The excess heat Qh is delivered to the outside.

Schematics of a refrigerator:

Energy conservation: Qh = Qc + W


Performance coeff:   κ ≡ Qc/W = (Qh/W)-1
Qc = useful output
W = input energy