Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles51y xzz
dz dx dy
xy⎛⎞∂∂⎛⎞
=+⎜⎟ ⎜⎟
⎝⎠∂∂⎝⎠Total energy E of a system is the sum of the numerous forms of energy such as thermal,
mechanical, kinetic, potential, electric, magnetic, chemical, and nuclear, and their
constituents. The total energy of a system on a unit mass basis is denoted by e and is
defined as E/m.
Total energy of a flowing fluid is the sum of the enthalpy, kinetic, and potential energies
of the flowing fluid.
Total enthalpy (see stagnation enthalpy)
Total temperature (see stagnation temperature)
Totally reversible process, or simply reversible process, involves no irreversibilities
within the system or its surroundings. A totally reversible process involves no heat
transfer through a finite temperature difference, no non-quasi-equilibrium changes, and
no friction or other dissipative effects.
Transport energy (see flow work).
Transonic flow occurs when a flow has a Mach number M ≅ 1.
Trap is a device that allows condensed steam to be routed to another heater or to the
condenser. A trap allows the liquid to be throttled to a lower-pressure region but traps the
vapor. The enthalpy of steam remains constant during this throttling process.
Triple line is the locus of the conditions where all three phases of a pure substance
coexist in equilibrium. The states on the triple line of a substance have the same pressure
and temperature but different specific volumes.
Triple point of water is the state at which all three phases of water coexist in
equilibrium.
Turbine is a device that produces shaft work due to a decrease of enthalpy, kinetic, and
potential energies of a flowing fluid.
Turbine efficiency is defined as the ratio of the mechanical energy output of the turbine
to the mechanical energy decrease of the fluid flow through the turbine.
Turbine firing temperature (see turbine inlet temperature)