Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles2Adiabatic saturation process is the process in which a steady stream of unsaturated air
of unknown specific humidity is passed through a long insulated channel that contains a
pool of water. As the air flows over the water, some water will evaporate and mix with
the airstream. The moisture content of air will increase during this process, and its
temperature will decrease, since part of the latent heat of vaporization of the water that
evaporates will come from the air. If the channel is long enough, the airstream will exit as
saturated air (100 percent relative humidity) at the exit temperature.
Adiabatic saturation temperature is the exit temperature that air attains in the adiabatic
saturation process.
Afterburner is a section added between the turbine and the nozzle of an aircraft turbine
engine where additional fuel is injected into the oxygen-rich combustion gases leaving
the turbine. As a result of this added energy, the exhaust gases leave at a higher velocity,
providing extra thrust for short takeoffs or combat conditions.
Air conditioners are refrigerators whose refrigerated space is a room or a building
instead of the food compartment.
Air–fuel ratio AF is a frequently used quantity in the analysis of combustion processes
to quantify the amounts of fuel and air. It is usually expressed on a mass basis and is
defined as the ratio of the mass of air to the mass of fuel for a combustion process.
Air-source heat pumps use the cold outside air as the heat source in winter.
Air-standard assumptions reduce the analysis of gas power cycles to a manageable
level by utilizing the following approximations:
- The working fluid is air, which continuously circulates in a closed loop and always
behaves as an ideal gas. - All the processes that make up the cycle are internally reversible.
- The combustion process is replaced by a heat-addition process from an external
source. - The exhaust process is replaced by a heat rejection process that restores the
working fluid to its initial state.
Air-standard cycle is a cycle for which the air-standard assumptions are applicable.
Amagat’s law of additive volumes states that the volume of a gas mixture is equal to the
sum of the volumes each gas would occupy if it existed alone at the mixture temperature
and pressure.
Annual fuel utilization efficiency AFUE is the efficiency of space heating systems of
residential and commercial buildings which accounts for the combustion efficiency as