MCT 433
Thermal Energy Analysis
Week 1
Energy Analysis Basics
Properties of Solids and Liquids
Objectives for This Week
Thermal Energy Applications

Course Overview

Temperature and Heat
Energy, Heat, Work
Closed Systems
Incompressible Substances (solids & liquids)
Temperature Measurement Lab - description
Weekly Assignment 1
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MCT433 Thermal Energy Analysis (Week 1) 2
Thermal Systems Analysis
MCT433 Thermal Energy Analysis (Week 1) 3
What is Thermodynamics?

Origin from Greek words therme ( ______ ) and dynamis ( ______ )

The study of
.

stored within matter of a system

transferred between a system and its surroundings by work, heat
transfer, and the flow of hot or cold streams of matter

converted from one form to another

Picks up where Physics left off.

What is energy?
MCT433 Thermal Energy Analysis (Week 1) 4
Thermodynamics vs Heat Transfer
Thermodynamics
 Concerned with the quantity
of energy transfer resulting
from a temperature difference
without regard to time.
Heat Transfer
 Uses transport laws to control
the rate of energy transferred
due to a temperature
difference.
MCT433 Thermal Energy Analysis (Week 1) 5
Temperature and the Zeroth Law of Thermodynamics


Two systems in equilibrium with a third system
are in thermal equilibrium with each other.
Example
3
1. Coffee
2. Red spirit (colored alcohol) in thermometer
3. Glass of thermometer
If T1 = T3 and T2 = T3, then T1 = T2
1
2
Image source: https://psiberg.com/zeroth-law-of-thermodynamics/
MCT433 Thermal Energy Analysis (Week 1) 6
Temperature (Temp.) Scales
 Conversions
𝑇 𝐾 = 𝑇 ℃ + 273.15
 𝑇 °𝑅 = 𝑇 ℉ + 459.67
 𝑇 ℉ = 1.8𝑇 ℃ + 32

 Change
in Temp.
∆𝑇 = 𝑇2 − 𝑇1
 ∆𝑇 𝐾 = ∆𝑇 ℃
 ∆𝑇 °𝑅 = ∆𝑇 ℉

 Unit
Systems
SI: °C and K
 US: °F and °R

Boil
Water
100°C
373.15 K
212°F
671.67°R
Body
Temp.
37°C
310.15 K
98.6°F
558.27°R
Room
Temp.
21°C
294.15 K
69.8°F
529.47°R
Freeze
water
0°C
273.15 K
32°F
491.67°R
0K
-459.67°F
0°R
K
Kelvin
°F
Fahreheit
°R
Rankine
Absolute
-273.15°C
zero
°C
Celsius
https://blog.beamex.com/temperature-units-and-temperature-unit-conversion
MCT433 Thermal Energy Analysis (Week 1) 7
Convert the Following Temperatures:
Fahrenheit
[℉ ]
Celsius
[℃ ]
Kelvin
[K]

100

68
Calculate temperature
differences between the first
two rows.
What do you notice?
0
0
-40
0
MCT433 Thermal Energy Analysis (Week 1) 8
Misconceptions about Temperature
Heat
 Heat is energy transfer from
burner to water
Temperature
 Thermometer measures the
temperature of water
Hyperlink: https://youtu.be/vqDbMEdLiCs
Image: https://www.yourdictionary.com/articles/heat-temp-difference
MCT433 Thermal Energy Analysis (Week 1) 9
Terminology

System:

Surroundings:

Boundary: (aka: control surface)
MCT433 Thermal Energy Analysis (Week 1) 10
Types of Systems
https://lawofthermodynamicsinfo.com/what-is-thermodynamic-system/
MCT433 Thermal Energy Analysis (Week 1) 11
Conservation of Energy
aka: First Law of Thermodynamics
Statement of the First Law:
MCT433 Thermal Energy Analysis (Week 1) 12
Energy In (positive) & Energy Out (negative)

How does energy enter or leave a system?




What is the difference between heat and work?
MCT433 Thermal Energy Analysis (Week 1) 13
For each illustration, what is the system???
Figure 3-43
The work (shaft) Done on an
adiabatic system is equal to
the increase in the energy of
the system.
Figure 3-44
The work (boundary) done
on an adiabatic system is
equal to the increase in the
energy of the system
Figure 3-45
The energy change of a system
during a process is equal to the
net work and heat transfer
between the system and its
surroundings.
MCT433 Thermal Energy Analysis (Week 1) 14
Forms of Energy
𝚫𝐄 = 𝚫𝐊𝐄 + 𝚫𝐏𝐄 + 𝚫𝐔
Energy
Macroscopic
Microscopic
(External)
(Internal)
Kinetic
1
𝐾𝐸 = 𝑚𝑣 2
2
Potential
𝑃𝐸 = 𝑚𝑔ℎ
Sensible
Latent
Chemical
Atomic
Molecular
movement
Phase
Changes
Bonds
between
atoms
Bonds
within
atoms
Image source: https://www.physicsclassroom.com/mmedia/energy/ie.cfm
More information at: Khan Academy about internal energy
MCT433 Thermal Energy Analysis (Week 1) 15
Describing Systems and Their Behavior
Term
Definition
State
System condition based on properties
Property
Characteristic that defines current state of a substance
Intensive
Extensive
Phases
Properties independent of size
(Pressure, temperature or density)
Properties related to size
(Mass or volume of system)
Homogeneous chemical/physical structure
(solid, liquid, or vapor)
Pure Substance Uniform chemical composition in one or more phases
MCT433 Thermal Energy Analysis (Week 1) 16
Describing Systems and Their
Behavior (cont.)
Term
Process
Equilibrium
Definition
When property or state changes
No change in mechanical, thermal,
chemical structure
QuasiAs mass is added or removed, system
Equilibrium
changes from one equilibrium state to a
new equilibrium state
Steady State
No change with time
Thermodynamic Sequence of processes
Cycle
No net change of state
Figure 3.4 Quasi-equilibrium
(Moran et al., 2002)
Figure 3.4 Illustration of a quasi-equilibrium expansion or compression. (Moran et al., 2002)
MCT433 Thermal Energy Analysis (Week 1) 17
Lower Image Source: https://www.sciencefacts.net/pv-diagram.html
Heat (Q) & Work (W)

Recognized ONLY across system boundary.

Associated with a


, not a
.
It’s not about the destination, but the journey.
Systems possess energy, not heat or work.
ΔE = ΔU = Q + W
MCT433 Thermal Energy Analysis (Week 1) 18
Energy Balance Example 1
A gas contained in a cylinder fitted with a frictionless piston is taken
from state A to state B along the path ACB as shown. On this path, 80 J
of heat flows into the system and the system does 30 J of work.
a) Use the First Law to write an expression for the
difference in energy between states A and B, EB - EA.
b) How much heat flows into the system for the process
P
represented by path ADB if the work done by the
system on this path is 10 J?
c) When the system returns from state B to state A
along the curved path BA, the work done on the
system is 20 J. What is the heat transfer for this
process?
MCT433 Thermal Energy Analysis (Week 1)
V
19
Workspace (Ein - Eout = EB – EA)
P
V
MCT433 Thermal Energy Analysis (Week 1) 20
Energy Balance Example 2
A closed system receives 168.7 kJ of heat at constant volume. It then
rejects 177 kJ of heat while it has 40 kJ of work done on it during an
isobaric process. If the energy of the system in the initial state is
arbitrarily set equal to 0 kJ, determine the energy of the system for each
of the other two states.
If an adiabatic process can be found which will restore it to its initial state,
how much work will be done by the system during that process?
MCT433 Thermal Energy Analysis (Week 1) 21
Workspace (U = Q – W)
State 1
U1 = 0 kJ
State 2
U2 =
kJ
State 3
U3 =
kJ
MCT433 Thermal Energy Analysis (Week 1) 22
Workspace
MCT433 Thermal Energy Analysis (Week 1) 23
What Happens to the Room Temperature?
What energy interactions are between the system and its surroundings?
MCT433 Thermal Energy Analysis (Week 1) 24
Specific Heat Capacity (c)
Q = 𝑚𝑐∆𝑇
m = 1kg
ΔT = 1K
𝑘𝐽
𝑐=5
𝑘𝑔 ∙ 𝐾
Q=
5kJ
Image Source: https://www.tec-science.com/thermodynamics/heat/specific-heat-capacity-ofMCT433 Thermal Energy Analysis (Week 1) 25
selected-substances/
Fluid(s)
IDEAL GAS
(constant specific
heats)
All gases other than
those for which
tables are given
INCOMPRESSIBLE
SUBSTANCE
PURE
SUBSTANCE
All solids; Liquids
Water, R-134a,
for which tables are ammonia (NH3),
not available
propane (C3H8) …
ASSUMPTIONS
Specific volume
()
Internal energy
(U or ΔU)
See handout for details
MCT433 Thermal Energy Analysis (Week 1) 26
Incompressible Substance Example…
A 2 lb steel rivet, initially at 1000℉, is placed in a large tank with
5 ft3 of liquid water at 70℉. How much heat is transferred to the
surroundings in the process of cooling the water and the rivet
back to 70℉?
MCT433 Thermal Energy Analysis (Week 1) 27
Workspace
MCT433 Thermal Energy Analysis (Week 1) 28
Closed System Example
A well-insulated copper tank (mass = 13 kg) contains 4 kg of liquid
water. The initial temperatures of the copper and water are 27℃ and
50℃, respectively. A 40 W electric resistance heater with negligible
mass operates for 20 minutes within the tank. What is the final
temperature when the tank and its contents come to equilibrium?
MCT433 Thermal Energy Analysis (Week 1) 29
Workspace
MCT433 Thermal Energy Analysis (Week 1) 30
Workspace
MCT433 Thermal Energy Analysis (Week 1) 31
Where have we been?
MCT433 Thermal Energy Analysis (Week 1) 32