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Chapter 1
Learning objectives:
1. Identify vocabulary to be used in the area of
thermodynamics
2. Review dimension and units
3. Closed and open systems
4. Introduce important concepts: state, properties,
process, cycle, energy, equilibrium
5. Measurement of properties pressure, density,
temperature
6. Problem solving techniques
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View Full Document Thermodynamics
:
A science which deals with heat and work and properties
of substances which are affected by heat and work.
•
We study the conservation of energy as a quantity
•
We determine the quality
of the energy
• We develop an understanding of properties of substances
System
:
All thermodynamic analyses begin with a choice of a system by
selecting a boundary.
“A system is any region in space bounded by a surface within which attention
is focused for study”
combustor
compressor
air
exhaust
turbine
fuel
Boundary
(imaginary surface)
System
Environment/surroundings
Introduction
Closed system
:
A fixed quantity of matter (mass) which is under study.
A
system for which no mass crosses the system boundary (as
time progresses).
Also called
control mass
.
Boundary may move
to contain fixed amount of matter.
work
heat
Initial state
Final state
* Note that heat and work can cross closed system boundaries.
Isolated system:
A special closed system which has no interactions with
The surroundings.
Closed System
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View Full Document Open system:
A fixed region of space through which mass and energy may flow.
Key distinction between open and closed system
mass crosses
boundary in open systems.
Also known as
control volume
.
Low
pressure
fluid
High
pressure
fluid
compressor
Open system
control
volume fixed
boundary
Open system control
volume with moving
boundary
Combustion products
Open System
Steam power plant
Boiler
Condenser
pump
Power
turbine
High temp source
Low temp sink
Boundary of closed
system, no mass
crosses
Fixed control volume
open system
Example Systems
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View Full Document Boiler
Cold fluid:
“liquid”
Hot fluid:
“steam”
Heat transfer
Heat transfer
Heat transfer
Work transfer
Heat & work
transfers are
allowed.
Mass
transfer not
allowed.
Example Systems
Boiler
Condenser
:
Macroscopic characteristics including such things as temperature,
pressure, density, velocity, position (elevation), volume, energy, etc.
which can be assigned a numerical value without a knowledge of the
history of the system.
State
:
The condition of a system as described by its properties.
When a sufficient set of property values are known, the
state of the system is known.
Example:
water (what constitutes a sufficient set of properties?)
H
2
O
H
2
O
liquid
vapor
T
1
= 50 ºC (121ºF)
P
1
= 1 atm
T
2
= 20 ºC
P
2
= 1 atm
T
3
= 100 ºC
P
3
= 1 atm
Properties
H
2
O is a liquid.
H
2
O is a solid.
Here H
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This note was uploaded on 10/07/2010 for the course MAE 5555555 taught by Professor Armstrong during the Fall '10 term at SUNY Buffalo.
 Fall '10
 Armstrong

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