Uploaded by Faith Bamgboye


Effurun, Delta State.
Term paper title:
Laws of Thermodynamics and Their Applications
Course title, code:
Basic Thermodynamics, MEE 216
Bamgboye Faith Abimbola
March, 2017.
1. Abstract…………......……………………………………………………………. 3
2. Introduction………………..............…...………………………………………… 4
3. Laws of Thermodynamics………………………......………………………….… 5
4. Applications of Laws of Thermodynamics…………………………………….... 12
5. Critiques or Limitations of Laws of Thermodynamics……………………...…… 16
6. Conclusion………………………………………………………………….…… 18
7. References………………………………………………………….……………. 19
Thermodynamics, field of physics that describes and correlates the physical
properties of macroscopic systems of matter and energy. The principles of thermodynamics
are of fundamental importance to all branches of science and engineering.
A central concept of thermodynamics is that of the macroscopic system, defined as
a geometrically isolable piece of matter in coexistence with an infinite, unperturbable
environment. The state of a macroscopic system in equilibrium can be described in terms
of such measurable properties as temperature, pressure, and volume, which are known as
thermodynamic variables. Many other variables (such as density, specific heat,
compressibility, and the coefficient of thermal expansion) can be identified and correlated,
to produce a more complete description of an object and its relationship to its environment.
When a macroscopic system moves from one state of equilibrium to another, a
thermodynamic process is said to take place. Some processes are reversible and others are
irreversible. The laws of thermodynamics, discovered in the 19th century through
painstaking experimentation, govern the nature of all thermodynamic processes and place
limits on them.
The laws of thermodynamics provide an elegant mathematical expression of some
empirically-discovered facts of nature. The principle of energy conservation allows the
energy requirements for processes to be calculated. The principle of increasing entropy
(and the resulting free-energy minimization) allows predictions to be made of the extent to
which those processes may proceed.
These laws are based on experimental observations and have no mathematical proof.
Like all physical laws, these laws are based on logical reasoning.
The four laws of thermodynamics define fundamental physical quantities
(temperature, energy, and entropy) that characterize thermodynamic systems at thermal
equilibrium. The laws describe how these quantities behave under various circumstances,
and forbid certain phenomena (such as perpetual motion).
The four laws of thermodynamics are:
Zeroth law of thermodynamics: If two systems are in thermal equilibrium with a
third system, they are in thermal equilibrium with each other. This law helps define the
notion of temperature. First law of thermodynamics: When energy passes, as work, as
heat, or with matter, into or out from a system, the system's internal energy changes in
accord with the law of conservation of energy. Equivalently, perpetual motion machines of
the first kind are impossible. Second law of thermodynamics: In a natural thermodynamic
process, the sum of the entropies of the interacting thermodynamic systems increases.
Equivalently, perpetual motion machines of the second kind are impossible. Third law of
thermodynamics: The entropy of a system approaches a constant value as the temperature
approaches absolute zero. With the exception of non-crystalline solids (glasses) the entropy
of a system at absolute zero is typically close to zero, and is equal to the logarithm of the
product of the quantum ground states. There have been suggestions of additional laws, but
none of them achieves the generality of the four accepted laws, and they are not mentioned
in standard textbooks.
The laws of thermodynamics are important fundamental laws in physics and they
are applicable in other natural sciences.
Zeroth law of thermodynamics states that if two systems are each equal in
temperature to a third, they are equal in temperature to each other. This law was
enunciated by R.H. Fowler in the year 1931. However, since the first and second laws
already existed at that time, it was designated as zeroth law so that it precedes the first and
second laws to form a logical sequence.
When two systems are in equilibrium, they share a certain property. This property
can be measured and a definite numerical value ascribed to it. A consequence of this fact
is the zeroth law of thermodynamics, which states that when each of two systems is in
equilibrium with a third, the first two systems must be in equilibrium with each other. This
shared property of equilibrium is the temperature.
If any such system is placed in contact with an infinite environment that exists at
some certain temperature, the system will eventually come into equilibrium with the
environment—that is, reach the same temperature. (The so-called infinite environment is a
mathematical abstraction called a thermal reservoir; in reality the environment need only
be large relative to the system being studied.)
For example: from the diagram above, if system ‘1’ consist of a mass of gas
enclosed in a rigid vessel fitted with a pressure gauge. If there is no change of pressure
when this system is brought into contact with system ‘2’ a block of iron, then the two
systems are equal in temperature (assuming that the systems 1 and 2 do not react each other
chemically or electrically). Experiment reveals that if system ‘1’ is brought into contact
with a third system ‘3’ again with no change of properties then systems ‘2’ and ‘3’ will
show no change in their properties when brought into contact provided they do not react
with each other chemically or electrically. Therefore, ‘2’ and ‘3’ must be in equilibrium.
Temperatures are measured with devices called thermometers. A thermometer
contains a substance with conveniently identifiable and reproducible states, such as the
normal boiling and freezing points of pure water. If a graduated scale is marked between
two such states, the temperature of any system can be determined by having that system
brought into thermal contact with the thermometer, provided that the system is large
relative to the thermometer.
The First Law of Thermodynamics can be stated as follows: “When a system
undergoes a thermodynamic cycle then the net heat supplied to the system from the
surroundings is equal to net work done by the system on its surroundings”.
The first law of thermodynamics may be stated in several ways:
The increase in internal energy of a closed system is equal to total of the energy
added to the system. In particular, if the energy entering the system is supplied as heat and
energy leaves the system as work, the heat is accounted as positive and the work is
accounted as negative.
∆Usystem = Q – W
In the case of a thermodynamic cycle of a closed system, which returns to its original
state, the heat Qin supplied to the system in one stage of the cycle, minus the heat Q out
removed from it in another stage of the cycle, plus the work added to the system Win equals
the work that leaves the system Wout.
∆Usystem(full cycle) = 0
Hence for a full cycle,
Q = Qin – Qout +Win – Wout = Wnet
For the particular case of a thermally isolated system (adiabatically isolated), the
change of the internal energy of an adiabatically isolated system can only be the result of
the work added to the system, because the adiabatic assumption is: Q = 0.
∆Usystem = Ufinal – Uintial = Win – Wout
The diagram below shows the experiment for checking the first law of
Heat and work
The work input to the paddle wheel is measured by the fall of weight, while the
corresponding temperature rise of liquid in the insulated container is measured by the
thermometer. It is already known to us from experiments on heat transfer that temperature
rise can also be produced by heat transfer. The experiments show: (i) A definite quantity
of work is always required to accomplish the same temperature rise obtained with a unit
amount of heat. (ii) Regardless of whether the temperature of liquid is raised by work
transfer or heat transfer, the liquid can be returned by heat transfer in opposite direction to
the identical state from which it started. The above results lead to the inference that work
and heat are different forms of something more general, which is called energy.
 It can be stated as an invariable experience that whenever a physical system
passes through a complete cycle the algebraic sum of the work transfers
during the cycle
bears a definite ratio to the algebraic sum of the heat transfers during
the cycle
this may be expressed as,
where J is the proportionality constant and is known as Mechanical
Equivalent of heat. In S.I. units its value is unity, i.e., 1 Nm/J.
More specifically, the First Law encompasses several principles:
 The law of conservation of energy. This states that energy can be neither created
nor destroyed. However, energy can change forms, and energy can flow from one
place to another. A particular consequence of the law of conservation of energy is
that the total energy of an isolated system does not change.
 The concept of internal energy and its relationship to temperature. If a system has
a definite temperature, then its total energy has three distinguishable components. If
the system is in motion as a whole, it has kinetic energy. If the system as a whole is
in an externally imposed force field (e.g. gravity), it has potential energy relative to
some reference point in space. Finally, it has internal energy, which is a fundamental
quantity of thermodynamics. The establishment of the concept of internal energy
distinguishes the first law of thermodynamics from the more general law of
conservation of energy.
Etotal = KEsystem + PEsystem + Usystem
The internal energy of a substance can be explained as the sum of the diverse kinetic
energies of the erratic microscopic motions of its constituent atoms, and of the potential
energy of interactions between them. Those microscopic energy terms are collectively
called the substance's internal energy (U), and are accounted for by macroscopic
thermodynamic property. The total of the kinetic energies of microscopic motions of the
constituent atoms increases as the system's temperature increases; this assumes no other
interactions at the microscopic level of the system such as chemical reactions, potential
energy of constituent atoms with respect to each other.
 Work is a process of transferring energy to or from a system in ways that can be
described by macroscopic mechanical forces exerted by factors in the surroundings,
outside the system. Examples are an externally driven shaft agitating a stirrer within
the system, or an externally imposed electric field that polarizes the material of the
system, or a piston that compresses the system. Unless otherwise stated, it is
customary to treat work as occurring without its dissipation to the surroundings.
Practically speaking, in all natural process, some of the work is dissipated by
internal friction or viscosity. The work done by the system can come from its overall
kinetic energy, from its overall potential energy, or from its internal energy. For
example, when a machine (not a part of the system) lifts a system upwards, some
energy is transferred from the machine to the system. The system's energy increases
as work is done on the system and in this particular case, the energy increase of the
system is manifested as an increase in the system's gravitational potential energy.
Work added to the system increases the Potential Energy of the system:
W = ∆PEsystem
Or in general, the energy added to the system in the form of work can be partitioned to
kinetic, potential or internal energy forms
W = KEsystem + PEsystem + Usystem
 When matter is transferred into a system, that masses' associated internal energy and
potential energy are transferred with it.
(u∆M)in = ∆Usystem
where u denotes the internal energy per unit mass of the transferred matter, as measured
while in the surroundings; and ΔM denotes the amount of transferred mass.
 The flow of heat is a form of energy transfer. Heating is a natural process of moving
energy to or from a system other than by work or the transfer of matter. Direct
passage of heat is only from a hotter to a colder system. If the system has rigid walls
that are impermeable to matter, and consequently energy cannot be transferred as
work into or out from the system, and no external long-range force field affects it
that could change its internal energy, then the internal energy can only be changed
by the transfer of energy as heat:
∆Usystem = Q
where Q denotes the amount of energy transferred into the system as heat.
Combining these principles leads to one traditional statement of the first law of
thermodynamics: it is not possible to construct a machine which will perpetually output
work without an equal amount of energy input to that machine. Or more briefly, a perpetual
motion machine of the first kind is impossible.
The second law of thermodynamics states that the total entropy of an isolated
system always increases overtime, or remains constant in ideal cases where the system is
in a steady state or undergoing a reversible process. The increase in entropy accounts for
the irreversibility of natural processes, and the asymmetry between future and past.
The second law of thermodynamics gives a precise definition of a property called
entropy. Entropy can be thought of as a measure of how close a system is to equilibrium;
it can also be thought of as a measure of the disorder in the system. The law states that the
entropy—that is, the disorder—of an isolated system can never decrease. Thus, when an
isolated system achieves a configuration of maximum entropy, it can no longer undergo
change: It has reached equilibrium. Nature, then, seems to “prefer” disorder or chaos. It
can be shown that the second law stipulates that, in the absence of work, heat cannot be
transferred from a region at a lower temperature to one at a higher temperature.
The second law is applicable to a wide variety of processes, reversible and
irreversible. All natural processes are irreversible. Reversible processes are a useful and
convenient theoretical fiction, but do not occur in nature.
A prime example of irreversibility is in the transfer of heat by conduction or
radiation. It was known long before the discovery of the notion of entropy that when two
bodies initially of different temperatures come into thermal connection, then heat always
flows from the hotter body to the colder one.
The second law tells also about kinds of irreversibility other than heat transfer, for
example those of friction and viscosity, and those of chemical reactions. The notion of
entropy is needed to provide that wider scope of the law.
According to the second law of thermodynamics, in a theoretical and fictive
reversible heat transfer, an element of heat transferred, δQ, is the product of the temperature
(T), both of the system and of the sources or destination of the heat, with the increment
(dS) of the system's conjugate variable, its entropy (S)
δQ = T dS.
Entropy may also be viewed as a physical measure of the lack of physical
information about the microscopic details of the motion and configuration of a system,
when only the macroscopic states are known. The law asserts that for two given
macroscopically specified states of a system, there is a quantity called the difference of
information entropy between them. This information entropy difference defines how much
additional microscopic physical information is needed to specify one of the
macroscopically specified states, given the macroscopic specification of the other - often a
conveniently chosen reference state which may be presupposed to exist rather than
explicitly stated. A final condition of a natural process always contains microscopically
specifiable effects which are not fully and exactly predictable from the macroscopic
specification of the initial condition of the process. This is why entropy increases in natural
processes - the increase tells how much extra microscopic information is needed to
distinguish the final macroscopically specified state from the initial macroscopically
specified state.
The third law of thermodynamics is sometimes stated as follows:
The entropy of a perfect crystal of any pure substance approaches zero as the temperature
approaches absolute zero. At zero temperature the system must be in a state with the
minimum thermal energy. This statement holds true if the perfect crystal has only one state
with minimum energy. Entropy is related to the number of possible microstates according
S = kB lnΩ
Where S is the entropy of the system, kB, Boltzmann's constant, and Ω the number
of microstates (e.g. possible configurations of atoms). At absolute zero there is only 1
microstate possible (Ω=1 as all the atoms are identical for a pure substance and as a result
all orders are identical as there is only one combination) and ln(1) = 0.
A more general form of the third law that applies to a system such as a glass that
may have more than one minimum microscopically distinct energy state, or may have a
microscopically distinct state that is "frozen in" though not a strictly minimum energy state
and not strictly speaking a state of thermodynamic equilibrium, at absolute zero
The entropy of a system approaches a constant value as the temperature approaches
zero. The constant value (not necessarily zero) is called the residual entropy of the system.
 The zeroth law of thermodynamics provides the basis for the measurement of
temperature. It enables us to compare temperatures of two bodies ‘1’ and ‘2’ with
the help of a third body ‘3’ and say that the temperature of ‘1’ is the same as the
temperature of ‘2’ without actually bringing ‘1’ and ‘2’ in thermal contact. In
practice, body ‘3’ in the zeroth law is called the thermometer. It is brought into
thermal equilibrium with a set of standard temperature of a body ‘2’, and is thus
calibrated. Later, when any other body ‘1’ is brought in thermal communication
with the thermometer, we say that the body ‘1’ has attained equality of temperature
with the thermometer, and hence with body ‘2’. This way, the body ‘1’ has the
temperature of body ‘2’ given for example by, say the height of mercury column in
the thermometer ‘3’.
 Application of the First Law to Flow process:
When a process is executed by a system, the change in stored energy of the
system is numerically equal to the net heat interactions minus the net work interaction
during the process.
E2 – E1 = Q – W
[or Q = ∆ E + W]
= ∆E = E2 – E1
where E represents the total internal energy.
If the electric, magnetic and chemical energies are absent and changes in potential
and kinetic energy for a closed system are neglected, the above equation can be written as
= ∆U = U2 – U1
Q – W = ∆U = U2 – U1
Generally, when heat is added to a system its temperature rises and external work is
performed due to increase in volume of the system. The rise in temperature is an indication
of increase of internal energy.
Heat added to the system will be considered as positive and the heat removed or
rejected, from the system, as negative.
 All types of vehicles that we use, cars, motorcycles, trucks, ships, aeroplanes, and
many other types work on the basis of Second law of thermodynamics and Carnot
Cycle. They may be using petrol engine or diesel engine, but the law remains the
Carnot Engine
The idealized Carnot engine was envisioned by the French physicist Nicolas Léonard Sadi Carnot, who
lived during the early 19th century. The Carnot engine is theoretically perfect, that is, it converts the
maximum amount of energy into mechanical work. Carnot showed that the efficiency of any engine
depends on the difference between the highest and lowest temperatures reached during one cycle. The
greater the difference, the greater the efficiency. An automobile engine, for example, would be more
efficient if the fuel burned hotter and the exhaust gas came out of the cylinder at a lower temperature.
© Microsoft Corporation. All Rights Reserved.
Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.
 All the refrigerators, deep freezers, industrial refrigeration systems, all types
of air-conditioning systems, heat pumps, etc work on the basis of the Second
law of thermodynamics.
 All types of air and gas compressors, blowers, fans, run on various
thermodynamic cycles.
 One of the important fields of thermodynamics is heat transfer, which relates
to transfer of heat between two media. There are three modes of heat transfer:
conduction, convection and radiation. The concept of heat transfer is used in
wide range of devices like heat exchangers, evaporators, condensers,
radiators, coolers, heaters, etc.
 Thermodynamics also involves study of various types of power plants like
thermal power plants, nuclear power plants, hydroelectric power plants,
power plants based on renewable energy sources like solar, wind,
geothermal, tides, water waves etc.
 Renewable energy is an important subject area of thermodynamics that
involves studying the feasibility of using different types of renewable energy
sources for domestic and commercial use.
Everyday Examples:
 Melting Ice Cube
Every day, ice needs to be maintained at a temperature below the freezing
point of water to remain solid. On hot summer days, however, people often take out
a tray of ice to cool beverages. In the process, they witness the first and second laws
of thermodynamics. For example, someone might put an ice cube into a glass of
warm lemonade and then forget to drink the beverage. An hour or two later, they
will notice that the ice has melted but the temperature of the lemonade has cooled.
This is because the total amount of heat in the system has remained the same, but
has just gravitated towards equilibrium, where both the former ice cube (now water)
and the lemonade are the same temperature. This is, of course, not a completely
closed system. The lemonade will eventually become warm again, as heat from the
environment is transferred to the glass and its contents.
 Sweating in A Crowded Room
The human body obeys the laws of thermodynamics. Consider the experience
of being in a small crowded room with lots of other people. In all likelihood, you'll
start to feel very warm and will start sweating. This is the process your body uses to
cool itself off. Heat from your body is transferred to the sweat. As the sweat absorbs
more and more heat, it evaporates from your body, becoming more disordered and
transferring heat to the air, which heats up the air temperature of the room. Many
sweating people in a crowded room, "closed system," will quickly heat things up.
This is both the first and second laws of thermodynamics in action: No heat is lost;
it is merely transferred, and approaches equilibrium with maximum entropy.
 Taking a Bath
Consider a situation where a person takes a very long bath. Immediately
during and after filling up the bathtub, the water is very hot -- as high as 120 degrees
Fahrenheit. The person will then turn off the water and submerge his body into it.
Initially, the water feels comfortably warm, because the water's temperature is
higher than the person's body temperature. After some time, however, some heat
from the water will have transferred to the individual, and the two temperatures will
meet. After a bit more time has passed, because this is not a closed system, the bath
water will cool as heat is lost to the atmosphere. The person will cool as well, but
not as much, since his internal homeostatic mechanisms help keep his temperature
adequately elevated.
 Hot Steam
Steam is the gaseous form of water at high temperature. The molecules
within it move freely and hence it has high entropy. If you cool this steam to below
100 degrees Celsius it will get converted into water, where the movement of the
molecules will be restricted resulting in decrease in entropy of water. When this
liquid is further cooled to below zero degrees Celsius, it gets converted into solid
ice, where the movement of molecules is further reduced and the entropy of the
substance further reduces. As the temperature of this ice goes on reducing the
movement of the molecules and along with it the entropy of the substance goes on
reducing. When this is ice is cooled to absolute zero ideally the entropy should
become zero. But in practical situations it is just not possible to cool any substance
to absolute zero temperature, nor does entropy become zero, but it remains always
above zero.
Zeroth Law
The limitation of zeroth law is that it cannot be derived from other laws and cannot
be applicable for other kinds of equilibrium i.e., It is only applicable for thermal
First Law
It has been observed that energy can flow from a system in the form of heat or work.
The first law of thermodynamics sets no limit to the amount of the total energy of a system
which can be caused to flow out as work. A limit is imposed, however, as a result of the
principle enunciated in the second law of thermodynamics which states that heat will flow
naturally from one energy reservoir to another at a lower temperature, but not in opposite
direction without assistance. This is very important because a heat engine operates between
two energy reservoirs at different temperatures. Further the first law of thermodynamics
establishes equivalence between the quantity of heat used and the mechanical work but
does not specify the conditions under which conversion of heat into work is possible,
neither the direction in which heat transfer can take place. This gap has been bridged by
the second law of thermodynamics.
Second Law
When a process satisfies the first law it implies that the process is possible in both
forward and reverse directions. The second law however, restricts that possibility only for
certain processes – the so called reversible processes. For irreversible processes, the second
law denies the possibility of occurrence of a process in a certain direction. For example,
the second law denies the direction of the process of conversion of energy in the form of
heat to energy in the form of work in a one-temperature (1-T) cyclic process; but not the
process per se, for, it allows the possibility of the process in the opposite direction - the
direction of conversion of energy in the form of work to energy in the form of heat in a 1T cyclic process. As a second example, we may consider transfer of energy in the form of
heat from a body at a given temperature to another body at a lower temperature. Second
law denies the possibility of occurrence of this process in the reverse direction.
The crux of the second law lies in the fact that it helps us to predict the direction in
which a process that satisfies the first law occurs under given conditions. It is the first law
that denies the process per se – when the process corresponds to perpetual motion of the
first kind – a process that produces energy as output with no input energy or more output
energy than the input energy. To conclude, the first law can deny the possibility of a
thermodynamic process, the second law can only deny the possibility of a cyclic process
in a certain direction. If a process AB is impossible, then the cycle ABA that takes the
system back to its original state, either in clockwise direction or anticlockwise direction,
becomes impossible. The second law is incapable of denying the occurrence of a cyclic
process that satisfies the first law, both in clockwise and anticlockwise directions.
Third Law
(1) Glassy solids even at 0oK has entropy greater than zero.
(2) Solids having mixtures of isotopes do not have zero entropy at 0oK. For instance,
entropy of solid chlorine is not zero at 0K.
(3) Crystals of CO, N2O, NO, H2O, etc. do not have perfect order even at 0K thus
their entropy is not equal to zero.
The laws of thermodynamics provide an elegant mathematical expression of some
empirically-discovered facts of nature. The principle of energy conservation allows
calculations to be made of the energy requirements for processes. The principle of
increasing entropy (and the resulting free-energy minimization) allows predictions to be
made as to the extent to which those processes may proceed.
Thermodynamics is considered to be one of the most important parts of our day-today life. Travelling in any vehicle, sitting comfortably in an air-conditioned room,
watching television etc., one will notice the applications of thermodynamics almost
everywhere directly or indirectly. When Sadi Carnot, who is considered to be the father
of thermodynamics, proposed theorem and cycle, hardly anybody had imagined that his
proposals will play such a major role in creation of automobiles that would become one of
most important parts of the human life. The development of almost all types of engines can
be traced to the Carnot Theorem and Carnot Cycle. One cannot forget the importance of
Stirling, Diesel, Otto and Ericsson also created their own independent cycles that resulted
in more innovations and betterment of the automobiles.
The study of thermodynamics involves various laws of thermodynamics that
include: First Law of Thermodynamics, Second Law of Thermodynamics, Third Law of
Thermodynamics, Zeroth Law of Thermodynamics, Boyle’s law, Charles Law, etc. The
foundation of these laws was laid by Sadi Carnot with his invention of the Carnot Cycle
and Carnot Theorem. Also, the study of the thermodynamics involves system and
surroundings where all the experimentation is done. There are various types of
thermodynamic processes (e.g. cyclic and flow processes) that help implementing
thermodynamic laws for various thermodynamic applications.
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2. Third law of thermodynamics – Wikipedia. Retrieved February 20, 2017 from
3. First law of thermodynamics – Wikipedia. Retrieved February 20, 2017 from
4. A Critique on Caratheodory Principle of the Second Law of Thermodynamics.
5. Applications of Thermodynamics Laws. Carnot, Stirling, Ericsson, Diesel cycles.
6. What Are Some Everyday Examples of the First & Second Laws of
Thermodynamics_ _ Education - Seattle PI. Retrieved March 2, 2017 from
7. Laws of thermodynamics – Wikipedia. Retrieved March 2, 2017 from
8. Thermodynamic process - Wikipedia. Retrieved March 2, 2017 from
9. Third law of thermodynamics, Limitations of Third law of thermodynamics,
10. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights
11. Rajput, R.K. (2007). ENGINEERING THERMODYNAMICS [For Engineering
Students of All Indian Universities and Competitive Examinations]. Darya Ganj,
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