Refrigeration Cycle: ConcepTest and Example Problem

Try to answer these ConcepTests before using this module. Studies show that trying to answer questions before studying material improves learning and retention. By the end of this module, you should be able to answer these ConcepTests on your own. Answers will be given at the end of this module.

An example problem on temperature entropy diagrams for a refrigeration cycle.
Example Problem 1

A refrigeration cycle using freon-12 is shown in the log pressure versus enthalpy plot. This cycle uses a throttle valve. The enthalpy and entropy values in the plot are from tables for freon-12. Calculate:
   1. Heat transferred at low temperature and at high temperature.
   2. Work input to refrigerator.
   3. The coefficient of performance (COP) for the cycle. 
   4. The COP if the compressor is only 70% efficient

Image of a pressure vs enthalpy plot for an example problem in the Refrigeration Cycle module.