Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles7mole fraction of the components as well as the mixture temperature and pressure, and is
independent of the identity of the other constituent gases.
Chemically correct amount of air is the stoichiometric or theoretical air, or 100 percent
theoretical air.
Choked flow occurs in a nozzle when the mass flow reaches a maximum value for the
minimum flow area. This happens when the flow properties are those required to
increase the fluid velocity to the velocity of sound at the minimum flow area location.
Choked Rayleigh flow occurs in a duct when a fluid can no longer be accelerated by
heating above sonic velocity to supersonic velocities.
Clapeyron equation, named after the French engineer and physicist E. Clapeyron
(1799–1864), relates the enthalpy change associated with a phase change (such as the
enthalpy of vaporization hfg) from knowledge of P, v, and T data alone.
Clapeyron–Clausius equation is used to determine the variation of saturation pressure
with temperature.
Classical thermodynamics is the macroscopic approach to the study of thermodynamics
that does not require knowledge of the behavior of individual particles.
Clausius inequality, first stated by the German physicist R. J. E. Clausius (1822–1888),
is expressed as the cyclic integral of δQ/T is always less than or equal to zero. This
inequality is valid for all cycles, reversible or irreversible.
Clausius statement of the second law is expressed as follows: It is impossible to
construct a device that operates in a cycle and produces no effect other than the transfer
of heat from a lower-temperature body to a higher-temperature body.
Clearance volume is the minimum volume formed in the cylinder when the piston is at
top dead center.
Closed feedwater heater is a feedwater heater in which heat is transferred from the
extracted steam to the feedwater without any mixing taking place. The two streams are
typically not at the same pressures, since they do not mix. In an ideal closed feedwater
heater the feedwater is heated to the exit temperature of the extracted steam, which
ideally leaves the heater as a saturated liquid at the extraction pressure. In actual power
plants the feedwater leaves the heater below the exit temperature of the extracted steam
because a temperature difference of at least a few degrees is required for any effective
heat transfer to take place.