Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles30Lower heating value LHV of fuel is the amount of heat released when a specified
amount of fuel (usually a unit of mass) at room temperature is completely burned, and the
combustion products are cooled to the room temperature when the water formed during
the combustion process leaves as a vapor.
Mach angle is the shock angle for Mach waves and is a unique function of the Mach
number.
Mach number, named after the Austrian physicist Ernst Mach (1838–1916), is the ratio
of the actual velocity of the fluid (or an object in still air) to the speed of sound in the
same fluid at the same state.
Mach wave is the weakest possible oblique shock at a Mach number.
Macroscopic forms of energy are those a system possesses as a whole with respect to
some outside reference frame, such as kinetic and potential energies.
Magnetic work is the product of the generalized force as the magnetic field strength
and the generalized displacement as the total magnetic dipole moment.
Manometer is a device based on the principle that an elevation change of Δz of a fluid
corresponds to a pressure change of ΔP/ ρg, which suggests that a fluid column can be
used to measure pressure differences. The manometer is commonly used to measure
small and moderate pressure differences.
Mass fraction is the ratio of the mass of one component in a mixture to the total mass of
the mixture.
Mass flow rate is the amount of mass flowing through a cross section per unit time.
Mass of a system is equal to the product of its molar mass M and the mole number N.
Maximum inversion temperature is the temperature at the intersection of the P= 0 line
(ordinate) on the T-P diagram and the upper part of the inversion line.
Maxwell relations are equations that relate the partial derivatives of properties P, v, T,
and s of a simple compressible system to each other.
Mayer relation, named in honor of the German physician and physicist J. R. Mayer
(1814–1878, shows how the difference between the constant-pressure specific heat and
constant-volume specific heat is related to the specific volume, temperature, isothermal
compressibility, and volume expansivity.