Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles19Extensive properties are those whose values depend on the size—or extent—of the
system. Mass m, volume V, and total energy E are some examples of extensive properties.
Extensive properties of a nonreacting ideal-or real-gas mixture are obtained by just
adding the contributions of each component of the mixture.
External combustion engines are engines in which the fuel is burned outside the system
boundary.
Externally reversible process has no irreversibilities to occur outside the system
boundaries during the process. Heat transfer between a reservoir and a system is an
externally reversible process if the surface of contact between the system and the
reservoir is at the temperature of the reservoir.
Fahrenheit scale (named after the German instrument maker
G. Fahrenheit, 1686–1736) is the temperature scale in the English system. On the
Fahrenheit scale, the ice and steam points are assigned 32 and 212 °F.
Fan is a device that increases the pressure of a gas slightly (typical pressure ratios are
less than 3) and is mainly used to mobilize a gas.
Fan-jet engine (see turbofan engine)
Fanno line is the locus of all states for frictionless adiabatic flow in a constant-area duct
plotted on an h-s diagram. These states have the same value of stagnation enthalpy and
mass flux (mass flow per unit area).
Feedwater heater is the device where the feedwater is heated by regeneration. This
technique is used to raise the temperature of the liquid leaving the pump (called the
feedwater) before it enters the boiler. A practical regeneration process in steam power
plants is accomplished by extracting, or “bleeding,” steam from the turbine at various
points. This steam, which could have produced more work by expanding further in the
turbine, is used to heat the feedwater instead.
First law (see first law of thermodynamics)
First law of thermodynamics is simply a statement of the conservation of energy
principle, and it asserts that total energy is a thermodynamic property. Joule’s
experiments indicate the following: For all adiabatic processes between two specified
states of a closed system, the net work done is the same regardless of the nature of the
closed system and the details of the process. It may be expressed as follows: Energy can
be neither created nor destroyed; it can only change forms. The net change (increase or
decrease) in the total energy of the system during a process is equal to the difference
between the total energy entering and the total energy leaving the system during that
process. The energy balance can be written explicitly as