PART 0
PRELUDE: REVIEW OF "UNIFIED ENGINEERING
THERMODYNAMICS"
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
01
PART 0
 PRELUDE: REVIEW OF “UNIFIED ENGINEERING THERMODYNAMICS”
[IAW pp 222, 3241 (see IAW for detailed SB&VW references); VN Chapter 1]
0.1
What it’s All About
The focus of thermodynamics in 16.050 is on the production of work, often in the form of
kinetic energy (for example in the exhaust of a jet engine) or shaft power, from different sources of
heat.
For the most part the heat will be the result of combustion processes, but this is not always the
case.
The course content can be viewed in terms of a “propulsion chain” as shown below, where we
see a progression from an energy source to useful propulsive work (thrust power of a jet engine).
In
terms of the different blocks, the thermodynamics in Unified Engineering and in this course are
mainly about how to progress from the second block to the third, but there is some examination of
the processes represented by the other arrows as well.
The course content, objectives, and lecture
outline are described in detail in Handout #1.
0.2 Definitions and Fundamental Ideas of Thermodynamics
As with all sciences, thermodynamics is concerned with the mathematical modeling of the
real world.
In order that the mathematical deductions are consistent, we need some precise
definitions of the basic concepts.
A
continuum
is a smoothedout model of matter, neglecting the fact that real substances are
composed of discrete molecules.
Classical thermodynamics
is concerned only with continua.
If
we wish to describe the properties of matter at a molecular level, we must use the techniques of
statistical mechanics
and
kinetic theory
.
A
closed system
is a fixed quantity of matter around which we can draw a boundary.
Everything
outside the boundary is the
surroundings
.
Matter cannot cross the boundary of a closed system
and hence the principle of the conservation of mass is automatically satisfied whenever we employ
a closed system analysis.
The
thermodynamic state
of a system is defined by the value of certain
properties
of that system.
For fluid systems, typical properties are pressure, volume and temperature.
More complex systems
may require the specification of more unusual properties.
As an example, the state of an electric
battery requires the specification of the amount of electric charge it contains.
Properties may be
extensive
or
intensive
.
Extensive properties are additive.
Thus, if the system is
divided into a number of subsystems, the value of the property for the whole system is equal to
the sum of the values for the parts.
Volume
is an extensive property.
Intensive properties do not
depend on the quantity of matter present.
Temperature
and
pressure are intensive properties.
Specific properties
are extensive properties per unit mass and are denoted by lower case letters.
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '02
 ZoltanSpakovszky
 Dynamics, Thermodynamics, Work, pistons

Click to edit the document details