1. Introduction
The air compression refrigeration cycle was studied long ago. Several disadvantages prevented air from
being used as a working fluid in refrigeration. These included the low volumetric refrigerating effect,
which may result in a large compressor, and the low COP due to the inefficiency of the compressor and
expander. After the invention of chlorofluorocarbons (CFCs) in the 1930’s, people paid little attention to
actual air compression refrigeration.