Introductory materials
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Thermodynamics
Cengel-PPT a b c Apps
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
What is Thermo…? Cengel-PPT a b c Apps
ENERGY Science
Energy Conversion
What is Energy…? www.kostic.niu.edu/energy
Cause Changes - Work, Heat, etc.
Energy is property of matter!
Therefore, ENERGY and
PROPERTY interrelations
Thermo Vocabulary
System, Surroundings, and Boundary
Closed System - Control Mass
Open System - Control Volume
Control Surface
Adiabatic System - NO Heat Transfer
Isolated System - NO Energy Transfer
Forms of Energy
TOTAL Energy
–
thermal, kinetic, potential, electric, magnetic,
nuclear, ….
Macroscopic vs. Microscopic
INTERNAL Energy (U)
- sum of ALL microscopic energies
System PROPERTIES
Extensive
–
m, V, U, E
Intensive
–
T, P, r, u, e
State, Equilibrium, Processes
State or Condition of a System
Equilibrium - System in balance,
NO Changes
–
–
–
–
thermal/temperature balance - no HEAT
transfer/adiabatic
mechanical/pressure balance - no WORK
transfer
phase - no change of phases
chemical - no change of spices
Pressure Scales
Gauge
pressure
Local atm. pressure
Standard atm. pressure
101.325 kPa(abs)
14.696 psi(a)
760 mmHg(a)
29.92 inHg(a)
Vacuum
pressure
Local
atm.
pressure
Absolute
pressure
Ch.8: Temperature
Measurement
Temperature:
measure of hotness or coldness
indicating the direction in which heat
(energy) will spontaneously flow, i.e., from a
hotter body (one at a higher temperature) to a colder one
(one at a lower temperature).
Temperature is not the equivalent of the
system energy
Historical background
Temperature Measurement
Devices
thermocouples,
resistive temperature devices (RTDs and
thermistors),
infrared radiators,
bimetallic devices,
liquid expansion devices, and
change-of-state devices.
8.2: Temperature Standards
Temperature scale (ITS-90)
Definition of the degree
Kelvin K, defined as the 1/273.16 fraction of the
thermodynamic temperature of the
triple point of water (TPW).
Fixed (reference) points
Interpolation between the fixed points
Thermo Laws
Zeroth Law:
TA=TC and TB=TC then TA=TB
First Law - Energy Conservation
Second Law - Process Direction
In Conclusion
Be imaginative
Try to differentiate
Make sense of what you study
Work and think hard and smart
Thermodynamics is a science of
ENERGY and MATTER and their relations