Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles31Mean effective pressure MEP is a fictitious pressure that, if it acted on the piston during
the entire power stroke, would produce the same amount of net work as that produced
during the actual cycle. The mean effective pressure can be used as a parameter to
compare the performances of reciprocating engines of equal size. The engine with a
larger value of MEP will deliver more net work per cycle and thus will perform better.
Mechanical efficiency of a device or process is the ratio of the mechanical energy output
to the mechanical energy input.
Mechanical energy is the form of energy that can be converted to mechanical work
completely and directly by an ideal mechanical device such as an ideal turbine.
Mechanical equilibrium is related to pressure, and a system is in mechanical
equilibrium if there is no change in pressure at any point of the system with time.
Mechanical work is work associated a force acting in the direction of motion that causes
the movement of the boundary of a system or the movement of the entire system as a
whole
Mechanisms of entropy transfer Sin and Sout are heat transfer and mass flow. Entropy
transfer is recognized at the system boundary as it crosses the boundary, and it represents
the entropy gained or lost by a system during a process. The only form of entropy
interaction associated with a fixed mass or closed system is heat transfer, and thus the
entropy transfer for an adiabatic closed system is zero.
Megapascal MPa is the unit of pressure equal to 10^6 pascal.
Melting line separates the solid and liquid regions on the phase diagram.
Metabolism is the thousands of chemical reactions that occur every second in the cells of
a body during which some molecules are broken down and energy is released and some
new molecules are formed. This high level of chemical activity in the cells maintains the
human body at a temperature of 37°C while performing the necessary bodily tasks.
Methane, CH 4 , is the approximation to gaseous hydrocarbon fuel natural gas that is a
mixture of methane and smaller amounts of other gases.
Methyl alcohol, CH 3 OH, is a common liquid hydrocarbon fuel that is also called
methanol and is used in some gasoline blends.
Metric SI (from Le Système International d’ Unités), which is also known as the
International System, is based on six fundamental dimensions. Their units, adopted in
1954 at the Tenth General Conference of Weights and Measures, are: meter (m) for
length, kilogram (kg) for mass, second (s) for time, ampere (A) for electric current,