Lecture Outlines
2000
Ian A. Waitz
THERMODYNAMICS:
COURSE INTRODUCTION
Course Learning Objectives:
To be able to use the First Law of Thermodynamics to estimate the potential for thermomechanical energy conversion in aerospace power and propulsion systems.
Measurable outcomes (assessment method):
1) To be able to state the First Law and to define heat, work, thermal efficiency and the difference between various forms of energy. (quiz, self-assessment, PRS)
2) To be able to identify and describe energy exchange processes (in terms of various forms of energy, heat and work) in aerospace systems. (quiz, homework, self-assessment, PRS)
3) To be able to explain at a level understandable by a high school senior or nontechnical person how various heat engines work (e.g. a refrigerator, an IC engine, a jet engine). (quiz, homework, self-assessment, PRS)
4) To be able to apply the steady-flow energy equation or the First Law of
Thermodynamics to a system of thermodynamic components (heaters, coolers, pumps, turbines, pistons, etc.) to estimate required balances of heat, work and energy flow. (homework, quiz, self-assessment, PRS)
5) To be able to explain at a level understandable by a high school senior or nontechnical person the concepts of path dependence/independence and reversibility/irreversibility of various thermodynamic processes, to represent these in terms of changes in thermodynamic state, and to cite examples of how these would impact the performance of aerospace power and propulsion systems.
(homework, quiz, self-assessment, PRS)
6) To be able to apply ideal cycle analysis to simple heat engine cycles to estimate thermal efficiency and work as a function of pressures and temperatures at various points in the cycle. (homework, self-assessment, PRS)
Teaching & Learning Methods
1) Detailed lecture notes are available on the web (for viewing and/or downloading).
You should download a copy of these and bring them with you to lecture.
2) Preparation and participation will be important for learning the material. You will be responsible for studying the notes prior to each lecture. Several reading
-1-
assignments will be given to help promote this activity (1/3 of participation grade). 3) Several active learning techniques will be applied on a regular basis (turn-to-yourpartner exercises, muddiest part of the lecture, and ungraded concept quizzes).
We will make extensive use of the PRS system (2/3 of participation grade).
4) Homework problems will be assigned (approximately one hour of homework per lecture hour). The Unified Engineering collaboration rules apply.
-2-
UNIFIED ENGINEERING
Lecture Outlines
2000
Ian A. Waitz
THERMODYNAMICS CONCEPTS
I.
Thermodynamics (VW, S & B: Chapter 1)
A. Describes processes that involve changes in temperature, transformation of energy, relationships between heat and work.
B. It is a science, and more importantly an engineering tool, that is necessary for describing the performance of propulsion systems, power generation systems, refrigerators, fluid flow, combustion,
....
C. Generalization of extensive empirical evidence (however most thermodynamic principles and can be derived from kinetic theory) D. Examples of heat engines
Combustion Heat
Solar Heat
Nuclear Heat
Mechanical Work
Electrical Energy
[ Heat Engine]
[Waste Heat ]
OR
Mechanical Work
Electrical Energy
[ Heat ]
Waste Heat
Fuel
Air
V1, T1
1. propulsion system
Air + fuel
V2, T2
Fuel
Air
Electricity
2. power generation
-3-
Electricity
Heat
3. Refrigerator
E. Questions:
1. Describe the energy exchange processes in ___________ (fill in the blank,
e.g. a nuclear power plant, a refrigerator, a jet engine).
2. Given that energy is conserved, where does the fuel+oxidizer energy that is used to power an airplane go?
3. Describe the energy exchange processes necessary to use electricity from a nuclear power plant to remove heat from the food in a refrigerator.
4. Describe the energy exchange processes necessary for natural gas to be used to provide electricity for the lights in the room you are in.
II.
Concept of a thermodynamic system (VW, S & B: 2.1)
A. A quantity of matter of fixed identity, boundaries may be fixed or movable, can transfer heat and work across boundary but not mass Force x distance (work)
System boundary
System boundary
Electrical energy
(work)
Heat (Q)
B. Identifiable volume with steady flow in and out, a control volume.
Often more useful way to view devices such as engines
System boundary
m, p1,T1 complex process
-4-
m, p2,T2
III. Thermodynamic state of a system
A. The thermodynamic state of a system is defined by specifying a set of measurable properties sufficient so that all remaining properties are determined. Examples of properties: pressure, temperature, density, internal energy, enthalpy, and entropy.
B. For engineering purposes we usually want gross, average, macroscopic properties (not what is happening to individual molecules and atoms) thus we consider substances as continua -the properties represent averages over small volumes. For example, there are 1016 molecules of air in 1 mm3 at standard temperature and pressure. (VW, S & B: 2.2)
. Intensive properties do not depend on mass (e.g. p, T, ρ, v=1/ρ, u and h); extensive properties depend on the total mass of the system (e.g. V, M, U and H). Uppercase letters are usually used for extensive properties. (VW, S & B: 2.3)
D. Equilibrium: States of a system are most conveniently described when the system is in equilibrium, i. e. it is in steady-state. Often we will consider processes that change “slowly” -- termed quasisteady. (VW, S & B: 2.3-2.4) thermally insulated copper boundary
Force
Gas 1
T1
Pressure
Gas 2
T2
Area
1. mechanical equilibrium
(force balances pressure times area)
-5-
Wait
Gas 1
T3
Gas 2
T3
2. thermal equilibrium
(same temperature)
E. Two properties are needed to define the state of any pure substance undergoing a steady or quasi-steady process. (This is an experimental fact!) (VW, S & B: 3.1, 3.3)
1. For example for a thermally perfect gas (this is a good engineering approximation for many situations, but not all (good for p
You May Also Find These Documents Helpful
-
Air in an ideal Diesel cycle is compressed from 4 L to 0.25 L, and then it expands during the constant pressure heat addition process to 0.50 L. Under cold air standard conditions, determine the thermal efficiency of this cycle.…
- 613 Words
- 3 Pages
Good Essays -
be clear enough to enable a first year science or engineering student to understand what you…
- 1241 Words
- 5 Pages
Powerful Essays -
The first law of thermodynamics states that energy is conserved.2 Using that law it can be said that the change in the internal energy of a system () depends on the heat added (q) to the system and the work (w) done by the system.2 Equation 1 illustrates the relationship between the three variables.…
- 1411 Words
- 6 Pages
Good Essays -
• • • • All forms of energy can be converted to heat Thermodynamics – “study of heat changes” Actually a type of kinetic energy Enthalpy (H): Heat content…
- 1121 Words
- 5 Pages
Good Essays -
theoretics. In order to teach, you must go through the steps, and make sure it is easily…
- 333 Words
- 1 Page
Satisfactory Essays -
In this assignment, you will complete tasks to demonstrate your understanding of the importance of…
- 1133 Words
- 5 Pages
Powerful Essays -
Hill’s law states that there exists a maximum force that a muscle can exert, and thus a maximum weight that a muscle can lift. Only one…
- 5145 Words
- 21 Pages
Satisfactory Essays -
Conservation of Energy- the principle that the amount of energy in an isolated system remains the same, even though the form of energy may change…
- 401 Words
- 2 Pages
Satisfactory Essays -
In this assignment, you will complete tasks to demonstrate your understanding of the importance of…
- 822 Words
- 4 Pages
Good Essays -
• Application and Analysis: This level deals with the use of abstract ideas, rules, or generalized methods and the understanding of relationships between elements or parts.…
- 2108 Words
- 9 Pages
Good Essays -
iii) knowledge of the main methods of enquiry in their subject(s), and ability to evaluate critically the appropriateness of different approaches to solving problems in the field of study;…
- 29634 Words
- 119 Pages
Powerful Essays -
For us to do work, we need energy. Energy is measured in joules, (J) or kilojoules (kJ)…
- 503 Words
- 3 Pages
Good Essays -
Teachers may reproduce this publication, in whole or in part, in limited print quantities for non-commercial, face-to-face teaching purposes. This permission does not apply to any third-party copyrights contained within this publication.…
- 5891 Words
- 24 Pages
Good Essays -
• Understand and observe the concept of Heat Transfer, by measuring the temperature distribution for steady state conduction of energy through a specific efficient unit.…
- 927 Words
- 4 Pages
Good Essays -
Q1 Q1 WX‐WR Q1‐WX Corollary 3: All reversible heat engines operating between the same two reservoirs have same efficiency. Since the second corollary has been proved true then it is impossible that one has higher efficiency. Thus according to the Carnot theorem both heat engines have same efficiency. i.e. η= (Q1+Q2)/Q1 = (T1‐T2)/T1 Corollary 4: A scale of temperature can be defined which is independent of any particular thermometric substance and which provides an absolute zero of temperature.…
- 648 Words
- 3 Pages
Satisfactory Essays