Lecture 1 Flashcards
can be defined as the science of
energy.
Thermodynamics
can be viewed as the ability to cause changes
Energy
most descriptive of the early efforts to convert heat into power
Thermodynamics
broadly interpreted to include all aspects of energy and
energy transformations including power generation,
refrigeration, and relationships among the properties of
matter
Thermodynamics
It simply states that during an interaction, energy can
change from one form to another but the total amount
of energy remains constant. That is, energy cannot be
created or destroyed
Conservation of Energy Principle
simply an expression
of the conservation of energy principle, and it asserts
that energy is a thermodynamic property.
first law of thermodynamics
asserts that energy
has quality as well as quantity, and actual processes
occur in the direction of decreasing quality of energy
second law of thermodynamics
study of thermodynamics
that does not require a knowledge of the behavior of
individual particles.
classical thermodynamics
based on the average
behavior of large groups of individual particles
statistical thermodynamics
characterized by any physical quantity can be
dimensions
The magnitudes assigned to
the dimensions
units
basic dimensions
such as mass m, length L, time
t, and temperature T
primary or fundamental
dimensions
expressed in terms of the
primary dimensions ex.
velocity, energy, volume
secondary dimensions or
derived dimensions
also
known as the United States
Customary System (USCS)
English system
(from Le Système International d’ Unités) also
known as the International system
metric SI
can simply be defined
as force times distance;
Work
defined as the energy
required to raise the temperature of 1 lbm of water at
68°F by 1°F.
Btu
(British thermal unit)
the amount of energy
needed to raise the temperature of 1 g of water at 14.5°C
by 1°C is defined as
1 calorie (cal)
unit for time rate of energy
joule per second (J/s) which is called watt (W)
every term in an equation must
have the same unit
Dimensional Homogeneity
defined as a
quantity of matter or a region in
space chosen for study.
System
The mass or region outside the
system
Surroundings
The real or imaginary surface that separates the system
from its surroundings
Boundary
The boundary of a system can be
Fixed or movable
contact surface shared by both the system and the surroundings. Mathematically
speaking, the blank has zero thickness, and thus it
can neither contain any mass nor occupy any volume in
space.
Boundary
consists of a fixed amount of
mass, and no mass can cross its
boundary
closed system (also known as a
control mass)
properly selected region in
space.
open system, or a control
volume
It usually encloses a device
that involves mass flow such as
a compressor, turbine, or
nozzle.
Open system or control volume
If, as a special case, even energy is not allowed to cross
the boundary, that system is called an
Isolated system
Any characteristic of a system. Pressure P,
temperature T, volume V, mass m
Property
those
that are independent of the
mass of the system
Intensive Properties
values
depend on the size or extent of
the system
Extensive Properties
extensive properties per unit
mass
Specific Properties
defined as mass
per unit volume
Density
The reciprocal of density, which
is defined as volume per unit mass
specific volume v
defined as the
ratio of the density of a substance to the density of
some standard substance at
a specified temperature
(usually water at 4°C, for
which ρH2O = 1000 kg/m3).
specific gravity or relative
density
weight of a unit volume of a substance
specific weight
condition of the system
State
implies a
state of balance
Equilibrium
there are no
unbalanced potentials (or
driving forces) within the
system.
Equilibrium State
the temperature
is the same throughout the entire
system.
Thermal equilibrium
related to
pressure; no change in pressure at any
point of the system with time
Mechanical Equilibrium
when the mass of
each phase reaches an equilibrium level
and stays there
Phase Equilibrium
chemical composition does not
change with time, that is, no chemical reactions occur
Chemical equilibrium
The state of a simple
compressible system is
completely specified
by two independent,
intensive properties.
The state postulate
Any change
that a system undergoes
from one equilibrium
state to another
Process
series of states through
which a system passes
during a process
Path of the process
a
process proceeds in such a manner that the system
remains infinitesimally close
to an equilibrium state at all
times
quasi-static (quasiequilibrium) process
used to designate a process for which a particular
property remains constant
Iso
is a process during which the
temperature T remains constant
Isothermal Process
is a process during which the pressure
P remains constant
Isobaric process
during which the
specific volume v remains constant
isochoric (or isometric) process
Implies no change
with time
steady
opposite of steady
unsteady (or transient)
implies no change
with location over a specified
region
Uniform
a
process during which a fluid
flows through a control
volume steadily
steady-flow process
states that if two bodies
are in thermal equilibrium with a third body, they are
also in thermal equilibrium with each other.
zeroth law of thermodynamics
two bodies are in thermal equilibrium if both have the
same temperature reading even if they are not in contact
Zeroth law of thermodynamics
Is defined as a normal force exerted by a fluid
per unit area.
Pressure
The counterpart of pressure in solids
Normal stress
The actual pressure at a given position is called
absolute pressure
indicate the
difference between the absolute pressure and the local
atmospheric pressure
Gage pressure
pressures below atmospheric pressure
vacuum pressures
The pressure is the same at
all points on a horizontal plane in a given fluid regardless
of geometry, provided that the points are
interconnected by the same fluid
hydrostatic conditions
Atmospheric pressure is
measured by a device
called
barometer
atmospheric
pressure is often
referred to as the
barometric pressure
it is
commonly used to measure small
and moderate pressure differences
Manometer
A system is called ________ in the absence
of electrical, magnetic,
gravitational, motion, and surface tension effects
simple compressible
system
