1. Engineering Thermodynamics
Basic Concepts - 1
Engineering Thermodynamics
Thermodynamics
Spring 2017
Basic Concepts - 1
Thermodynamics

2. Outline General overview What is thermodynamics?
History of thermodynamics
Why do we study thermodynamics? General thermodynamic systems Closed vs. open systems
Macroscopic vs. microscopic viewpoints
ISHIK UNIVERSITY

3. The engineering framework
THEORY
DATA
JUDGMENT
(DESIGN)

4. General overview Mechanical Engineering Thermodynamics
Mechanics Energy Systems Design
The over arching goal is design of products to meet societal needs.
Thermodynamics
A part of the Energy component of mechanical engineering.
Governs all energy consuming and transforming devices and system.

5. Thermodynamics and Energy
Thermodynamics is defined as the science of Energy and includes all aspects of energy transformations, including power production, refrigeration, and relationship among the properties of matter.
The first law of thermodynamics is simply an expression of the conservation of energy principle, and it asserts that energy is a thermodynamic property.
The second law of thermodynamics asserts that energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality of energy → “entropy”.

6. History of Thermodynamics
Greeks: “the power of heat”
To understand steam engines in the 18th century

7. Motivations
Power plants Automotive engines Aircraft engines HVAC and IAQ Advanced TD systems
Power MEMS
Fuel cells
Thermodynamics

8. Example: A steam power plant
Combustion
Products
Steam
Turbine
Mechanical Energy to Generator
Fuel
Air
Heat
Exchanger
Pump
System Boundary for Thermodynamic Analysis
Cooling Water
Thermodynamics

9. Example: A gas turbine engine
Fuel Flow In
Combustor
Air Flow In
Shaft Work Output
Compressor Work Out
Exhaust Gases Out
Thermodynamics

10. Example: An automotive engine
Thermodynamics

11. Piston Gas at pressure, p Example: Piston and cylinder m
Thermodynamics

12. General thermal systems (heat engines)
Thermodynamics

13. General thermal systems
(refrigerator and heat pump)
Thermodynamics

14. How does the state of system change?
Thermodynamics

15. Basic Concepts - 1
Basic definitions...
Thermodynamics

16. System, Surroundings and Boundary
Basic Concepts - 1
System, Surroundings and Boundary
A Thermodynamic System, or simply System is defined as a quantity of matter or a region in space chosen for study.
Surroundings is the mass or region outside the system.
Boundary is the real or imaginary surface that separates the system from its surroundings.
Thermodynamics

17. Basic Concepts - 1
Closed and Open System
A system of fixed mass is called a Closed System, or Control Mass, and a system that involves mass transfer across its boundaries is called an Open System, or Control Volume.
Thermodynamics

18. Closed and Open System Control Mass vs. Control Volume.
Basic Concepts - 1
Closed and Open System
Control Mass
vs. Control Volume.
Thermodynamics

19. Basic Concepts - 1
Isolated System
An Isolated System is a general system of fixed mass where no heat or work may cross the boundaries. An isolated system is a closed system with no energy crossing the boundaries and is normally a collection of a main system and its surroundings that are exchanging mass and energy among themselves and no other system.
Isolated System Boundary
Heat = 0
Work = 0
Mass = 0 Across Isolated Boundary
Work
Surr 4
Mass
System
Surr 3
Surr 1
Mass
Heat
Surr 2
Thermodynamics

20. Basic Concepts - 1
Control volume
A control volume may involve fixed, moving, real, and imaginary boundaries.
Thermodynamics

21. Interactions between system and surroundings...
Basic Concepts - 1
Interactions between system and surroundings...
Thermodynamics

22. Closed system - summary
Basic Concepts - 1
Closed system - summary
Surroundings
Heat
System
Work
Thermodynamics

23. System Open system - summary Surroundings Mass Flow Heat Mass Flow
Basic Concepts - 1
Open system - summary
Surroundings
Mass Flow
Heat
System
Mass Flow
Power
Thermodynamics

24. Piston Gas at pressure, p
Basic Concepts - 1
Example: Piston and cylinder - a closed system m
Piston
Gas at pressure, p
Thermodynamics

25. Example: The gas turbine engine - an open system
Basic Concepts - 1
Example: The gas turbine engine - an open system
Fuel Flow In
Combustor
Air Flow In
Shaft Work Output
Compressor Work Out
Exhaust Gases Out
Thermodynamics

26. Macroscopic vs. microscopic
Basic Concepts - 1
Macroscopic vs. microscopic
viewpoints...
A collection of atoms within a container, each with a unique velocity.
Thermodynamics

27. The macroscopic description
Basic Concepts - 1
The macroscopic description
The energy in both cases is the same, E. In the macroscopic description, atomistic concepts are disregarded.
How we describe the
system chosen for study requires careful selection of properties that are based on observable, measurable quantities.
Thermodynamics

28. The macroscopic viewpoint...
Basic Concepts - 1
The macroscopic viewpoint...

29. Basic Concepts - 1
State of a thermodynamic system.
Enumeration of all of its properties.
In macroscopic thermodynamics, the properties of system are assigned to the system as a whole.
Thermodynamics

30. Density of common substances
Basic Concepts - 1
Density of common substances
Thermodynamics