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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsINTRODUCTION AND BASIC CONCEPTS
Thermodynamics and Energy Importance of Dimensions and Units
System and Control Volume Properties of A System State and
Equilibrium Processes and Cycles Temperature and Zeroth Law of
Thermodynamics Pressure The manometer The barometer and Atmospheric
Pressure
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.1 Thermodynamics & Energy Thermodynamics can be
define as the science of energy. Conservation of energy - it state
that during an interaction, energy can change from one form to
another but the total amount of energy remains constant. Energy
cannot be created or destroyed.
A rock falling off a cliff
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsA person has a greater energy input (food) than
energy output (exercise) will gain weight (store energy in the form
of fat) The change in energy content of a body or any other system
is equal to the difference between the energy input and the energy
output. Energy balance is expressed Ein Eout =E
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsApplication Areas of Thermodynamics
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.2 Importance of Dimensions and UnitsThe seven
fundamental dimensions and their units in SI
DimensionUnitLengthMeter (m)MassKilogram (kg)TimeSecond
(s)TemperatureKelvin (K)Electric currentAmpere (A)Amount of
lightCandela (cd)Amount of matterMole (mol)
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsThey are standard for all units and the student is
encouraged to memorize them because of their widespread use.Some SI
and English units
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.3 Systems and Control Volumes Surrounding the mass
or region outside the system Boundary the real or imaginary surface
that separates the system from its surrounding Close system
(control mass) consists of a fix amount of mass, and no mass can
cross its boundary Isolated system a special case, even energy is
not allowed to cross boundary
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsAn open system or a control volume, is a properly
selected region in space. It usually enclose a device that involves
mass flow such as a compressor or turbine. Flow through these
devices is best studied by selecting the region within the device
as the control volume. Both mass and energy can cross the boundary
of a control volume.
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.4 Properties of A System Property any
characteristic of a system, e.g. pressure, P temperature, T volume,
V and mass m Intensive properties those that are independent of the
mass of a system, such as temperature, pressure and density
Extensive properties - those whose values depend on the size _or
extent_ of the system such as total mass, total momentum and total
volume
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.5 State and Equilibrium State set of properties
that completely describe the condition, at the given state all the
properties of the system have fix values, if the value of even one
property changes, the state will change to different one
Equilibrium implies a state of balance, e.g. thermal equilibrium,
the temperature is the same throughout the entire system, the
system involves no temperature differential.
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.6 Processes and Cycles Process any change that a
system under goes from one equilibrium state to another Path the
series of states through which a system passes during a process
Quasi-equilibrium process as a sufficiently slow process that
allows the system to adjust itself internally so the properties in
one part of the system do not change any faster than those at other
parts
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to Thermodynamics
Thermodynamics cycle when a system starts at an initial state and
undergoes a sequence of changing states and then returns to its
initial state Chapter 1: End of first part
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.7 Temperature and The Zeroth Law of Thermodynamics
Temperature as a measure of hotness or coldness Zeroth Law of
Thermodynamics if two bodies are in thermal equilibrium with a
third body, they are also in thermal equilibrium with each
other
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsTemperature Scales Kelvin scale is related to the
Celsius scale byT(K) = T (oC) + 273.15 Rankine scale is related to
the Fahrenheit byT(R) = T (oF) + 459.67 The temperature scales in 2
units systemT(R) = 1.8T(K)T (oF) =1.8T (oC) +32
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.8 Pressure Pressure a normal force exerted by a
fluid per unit area, it has the unit of newtons per square meter
(N/m2), which is called a pascal (Pa)
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1 bar = 105 Pa = 0.1 MPa = 100 kPa1 atm = 101,325 Pa
= 101.325 kPa = 1.01325 bars
Pgage = Pabs PatmPvac = Patm - Pabs
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.9 The ManometerManometer commonly used to measure
small and moderates pressure differences
P2 = Patm + gh
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsDetermine the absolute pressure, P Determine the
absolute pressure, P1
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics1.10 The Barometer and Atmospheric Pressure
Atmospheric Pressure is measured by a device called a barometer
and is referred to as the barometric pressure
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
ThermodynamicsEffect of piston weight on pressure in a
cylinderDetermine the absolute pressure, P Chapter 1: End of second
part
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EPT 201 THERMODYNAMICS Chapter 1: Introduction to
Thermodynamics