« Maximize »

Problem 21.8: Refrigerator and entropy

refrigerator cycle:

Please wait for the animation to completely load.

There is a time delay-since the system must be in equilibrium-before the initial change of state occurs.

You must go in order.

In this animation N = nR (i.e., kB = 1). This, then, gives the ideal gas law as PV = NT. Assume an ideal gas. Restart.

The reverse of an engine is a refrigerator. An engine uses heat to produce work, while a refrigerator does negative work on the gas (something else does work on the gas) to remove heat. The coefficient of performance is K = |QC|/|W| (heat transferred out of the cold reservoir divided by the work required)

  1. In which step is the heat removed from the cold reservoir (i.e., heat removed from the refrigerator and absorbed by the gas)?
  2. In which step is work done on the gas?
  3. For the refrigerator, find the work done during each cycle, the heat transferred from the cold reservoir, and the coefficient of performance.
  4. What is the change in entropy for the complete cycle?

Problem authored by Anne J. Cox.

Physlets were developed at Davidson College and converted from Java to JavaScript using the SwingJS system developed at St. Olaf College.

OSP Projects:
Open Source Physics - EJS Modeling
Physlet Physics
Physlet Quantum Physics
STP Book