Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles44Simple cooling is the process of lowering the temperature of atmospheric air when no
moisture is removed.
Simple heating is the process of raising the temperature of atmospheric air when no
moisture is added.
Simultaneous reactions are chemical reactions that involve two or more reactions
occurring at the same time.
Sling psychrometer is a device with both a dry-bulb thermometer and a wet-bulb
temperature mounted on the frame of the device so that when it is swung through the air
both the wet-and dry-bulb temperatures can be read simultaneously.
Solid phase has molecules arranged in a three-dimensional pattern (lattice) that is
repeated throughout. Because of the small distances between molecules in a solid, the
attractive forces of molecules on each other are large and keep the molecules at fixed
positions.
Solubility represents the maximum amount of solid that can be dissolved in a liquid at a
specified temperature.
Sonic flow occurs when a flow has a Mach number M =1.
Sonic speed (see speed of sound)
Spark-ignition (SI) engines are reciprocating engines in which the combustion of the
air–fuel mixture is initiated by a spark plug.
Specific gravity, or relative density, is defined as the ratio of the density of a substance
to the density of some standard substance at a specified temperature (usually water at
4 °C, for which the density is 1000 kg/m^3 ).
Specific heat is defined as the energy required to raise the temperature of a unit mass of a
substance by one degree. In general, this energy will depend on how the process is
executed.
Specific heat at constant pressure Cp is the energy required to raise the temperature of
the unit mass of a substance by one degree as the pressure is maintained constant. Cp is a
measure of the variation of enthalpy of a substance with temperature. Cp can be defined
as the change in the enthalpy of a substance per unit change in temperature at constant
pressure.
Specific heat at constant volume Cv is the energy required to raise the temperature of
the unit mass of a substance by one degree as the volume is maintained constant. Cv is