Glossary of Thermodynamic Terms

beginning with the letter...

Primary Word
Secondary Word
Tutorial Page Link
efficiency 6A7
efficiency Carnot 6E1  ,  3 - 22
efficiency isothermal 8C15  ,  16
efficiency second law 8D6
efficiency thermal 6B4
effluent 5B4
electrical work 4C5
emissivity The ratio of the radiation emitted by a real surface to the radiation emitted by a blackbody. It is a measure of how effectively the surface radiates. 4B22
energy The capacity to do work. 3C1
energy conservation of First law of Thermodynamics.  In the absence of nuclear reactions, energy cannot be created or destroyed.  Energy can only change form or be transferred. 1A3
energy internal The sum of all of the energies associated with moleules of a piece of matter.  This includes the energies associated with the molecular structure and all of the microscopic forms of energy of a group of molecules: vibrational, translational and rotational energies. 3A2 - 3
energy kinetic The energy associated with any piece of matter that is attributed to the macroscopic or average velocity of the molecules that make up the piece of matter.   4C7
energy potential The energy of a piece of matter associated with the position of the matter within a potential field.  The field is usually gravitational. 4C7
energy rotational The energy associated with the atoms of a polyatomic molecule rotating about an axis. 2A4
energy total 4C1  ,  5
energy translational The energy associated with a molecule of gas traveling through space with a linear velocity, thus possessing kinetic energy. 2A4
energy vibrational The energy associated with the atoms of a polyatomic molecule vibrating about their common center of mass.  This refers to the stretching, flexing and deformation the molecule and its bonds. 2A4
energy balance 5B1 - 6  ,  9 - 11
energy balance differential 5B2
enthalpy From the Greek word enthalpien, which means to heat:  H = U + PV 3A5
enthalpy definition 3A5
enthalpy ideal gas 3A7
enthalpy incompressible liquids 3A8
enthalpy of Fusion Also known as the Heat of Fusion, Latent Heat of Fusion and Latent Enthalpy of Fusion.  Enthalpy of Fusion is the amount of energy released when a substance makes the transition from the liquid phase to the solid phase.  Values of the Enthalpy of Fusion are typically tabulated at the normal melting point (temperature).  [kJ/kmol] 3E13
enthalpy of Sublimation Also known as the Heat of Sublimation, the Latent Heat of Sublimation and the Latent Enthalpy of Sublimation.  Enthalpy of Sublimation is the amount of energy required when a substance makes the transition directly from the solid phase to the vapor phase.  The Enthalpy of Sublimation is a function of temperature.  [kJ/kmol] 3E13
enthalpy of Vaporization Also known as the Heat of Vaporization, the Latent Heat of Vaporization and the Latent Enthalpy of Vaporization.  Represents the amount of energy required to vaporize a unit mass of saturated liquid at a given temperature or pressure. [kJ/kmol] 3E2
enthalpy real substance 3A6
enthalpy solids 3A8
enthalpy specific 5B10
entropy 7A1
entropy how to evaluate 7B3
entropy integral form of the definition 7D1 - 3
entropy units 7B3
entropy balance 8A1  ,  4
entropy balance closed system 8A4
entropy balance differential form 8A4
entropy balance integral form 8A4
entropy balance open system 8B1  ,  2  ,  4 - 11
entropy balance rate form 8A4
entropy balance single inlet, single outlet 8B5
entropy balance steady-state 8B4  ,  5
entropy change closed system 8A3
entropy change ideal gas 7D8 - 14
entropy change incompressible liquids 7D6  ,  7
entropy change internally reversible, isothermal 7B4
entropy change irreversible process 7B5
entropy change negative 7C7
entropy change non-isothermal process 7D2
entropy change reversible process 7B5
entropy change solids 7D6  ,  7
entropy change thermal reservoir 7B4
entropy change universe 7C6  ,  7
entropy generation 7C1  ,  7
entropy generation external 8D4
entropy generation inexact differential 7C3
entropy generation internal 8D4
entropy generation irreversibility 7C3
entropy generation irreversible process 7C3
entropy generation path variable 7C3
entropy generation reversible process 7C3
entropy generation total 8D4  ,  5
entropy inequality 7C2
equation of state (EOS) An EOS is an equation that relates pressure, volume and temperature.  Given any 2 of the 3 variables (P, V, T) an equation of state can be used to determine the unknown third variable. 2E1
equation of state (EOS) generalized compressibility factor A graphical EOS based on the principle of corresponding states.  The Generalized Compressibility Factor EOS manifests itself in the Generalized Compressibility Charts.  The key parameter in the Generalized Compressibility Factor EOS is the Compressibility Factor, Z. 2E7
equation of state (EOS) ideal gas The simplest EOS :  PV=nRT.  It is accurate to within 1% when the molar volume of a gas exceeds 20 L/mole.  It can be used accurately for diatomic gases and most noble gases as long as the molar volume exceeds 5 L/mole 4A18
equation of state (EOS) Redich-Kwong A cubic, empirical EOS that accurately represents the behavior of a wide variety of systems.  Its two parameters are empirical functions of the critical temperature and pressure. 2F7
equation of state (EOS) Soave-Redlich-Kwong (SRK) A cubic, empirical EOS that accurately represents the behavior of a wide variety of systems, especially hydrocarbons.  Its three parameters are empirical functions of the critical temperature and pressure and the Pitzer Accentric Factor. 2F8
equation of state (EOS) van der Waals The original cubic EOS, the van der Waals EOS is not empirical in nature, but has a theoretical basis.  The derivation of the van der Waals EOS yields two parameters that are functions of the critical temperature and pressure.  One of the parameters accounts for the attractive forces between the molecules and the other parameter represents the volume that the molecules themselves occupy. 2F4
equation of state (EOS) Virial The Virial EOS is a power series expansion in terms of the inverse of the molar volume.  The parameters of the Virial EOS can be interpreted in terms of statistical mechanics.  The 2nd Virial Coefficient, B, is widely tabulated and its value for a pure compound at a given temperature can be estimated using the critical temperature and pressure and the Pitzer Accentric Factor. 2F2
equilibrium Equilibrium is a state of balance.  No unbalanced potentials (or driving forces) exist within the system.  If isolated from its surroundings a system at Equilibrium experiences no changes. 1D5
equilibrium chemical 1D5
equilibrium mechanical 1D5  ,  6
equilibrium phase In a system at Phase Equilibrium, the rate at which molecules are making the transition OUT of each and every phase is exactly equal to the rate at which molecules are making the transition INTO the same phase. 1D5
equilibrium thermal 1D5
equilibrium vapor-liquid 2B2
equilibrium state 6A4  ,  6
evaporation Also known as vaporization.  A process in which a molecule makes the transition from a liquid phase into the gas phase while the vapor pressure of the liquid phase is LESS than the total pressure of the system. 2A8
evaporator 6B7  ,  9
exact differential The differentials of state variables or properties are exact differentials and they are represented by the prefix "d".  For example: dV or dT. 4A7 - 8  ,  12
expansion 4A1  ,  11
expansion adiabatic 6E6  ,  10  ,  11
expansion isothermal 6E4  ,  10  ,  11
expansion reversible 6E2
expansion valve 6B7  ,  9
extensive property Properties that depend on the size of the system.  If you magically insert a divider that divides the system into two equal halves and consider just one of the half-systems, the value of any and all extensive properties will also be reduced by half.  Examples of extensive variables include mass, volume and enthalpy. 3C4
external combustion 9E2  ,  3
externally reversible 6D9