Refer to figure D.4 for the physical device to be
analyzed. The refrigerant circulating through the device is an ideal
gas with constant specific heats, like a thin gas of helium atoms.
Chapter 11.14 will examine ideal gases in detail, but for
now some reminders from introductory classical physics classes about
ideal gasses must do. The internal energy of the gas is
The differential version of the first law, energy conservation,
(11.11), says that
Now for the transitions through the heat exchangers, from 1 to 2 or
from 3 to 4 in figure D.4, the temperature is
approximated to be constant. The first law above can then be
integrated to give the heat added to the substance as:
On the other hand, for the transitions through the adiabatic turbine
and compressor, the heat