Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles37Prandtl–Meyer function is the angle through which flow must expand, starting with the
function value of zero at Ma = 1, in order to reach a supersonic Mach number, Ma > 1.
Pressure is defined as the force exerted by a fluid per unit area.
Pressure fraction of a gas component in a gas mixture is the ratio of the component
pressure to the mixture pressure. Note that for an ideal-gas mixture, the mole fraction, the
pressure fraction, and the volume fraction of a component are identical.
Pressure ratio is the ratio of final to initial pressures during a compression process.
Pressure transducers are made of semiconductor materials such as silicon and convert
the pressure effect to an electrical effect such as a change in voltage, resistance, or
capacitance. Pressure transducers are smaller and faster, and they are more sensitive,
reliable, and precise than their mechanical counterparts.
Primary or fundamental dimensions, such as mass m, length L, time t, and temperature
T, are the basis for the derivation of secondary dimensions.
Principle of corresponding states is the fact that compressibility factor Z for all gases is
approximately the same at the same reduced pressure and temperature.
Problem-solving technique is a step-by-step approach to problem solving discussed in
Chapter 1.
Process is any change that a system undergoes from one equilibrium state to another. To
describe a process completely, one should specify the initial and final states of the
process, as well as the path it follows, and the interactions with the surroundings.
Process heat is required energy input in the form of heat for many industrial processes.
The process heat is often obtained as heat transfer from high-pressure, high-temperature
steam. Some industries that rely heavily on process heat are chemical, pulp and paper, oil
production and refining, steel making, food processing, and textile industries.
Products are the components that exist after the reaction in a combustion process.
Property is any characteristic of a system. Some familiar properties are pressure P,
temperature T, volume V, and mass m. The list can be extended to include less familiar
ones such as viscosity, thermal conductivity, modulus of elasticity, thermal expansion
coefficient, electric resistivity, and even velocity and elevation.
Propjet engine is a turbojet engine in which the shaft work is used to drive the propeller.