2. A presentation on
“ Basic
Thermodynamics
Cycle”
Presented By:
A. S. M Muhtasim Fuad Sohan
Department Of EEE
Student ID: 151061
3. What is Thermodynamics ?
Thermodynamics is a branch of physics
concerned with heat and temperature and
their relation to energy and work. It defines
macroscopic variables, such as internal
energy, entropy, and pressure, that partly
describe a body of matter or radiation. It
states that the behavior of those variables is
subject to general constraints, that are
common to all materials, beyond the peculiar
properties of particular materials. These
general constraints are expressed in the four
laws of thermodynamics.
4. “
Basic Thermodynamics Cycle
Isobaric process: occurs at constant pressure
Isochoric process: occurs at constant volume (also called isometric/isovolumetric)
Isothermal process: occurs at a constant temperature
Adiabatic process: occurs without loss or gain of energy as heat
5. “o Isentropic process: a reversible adiabatic process occurs at a constant
entropy, but is a fictional idealization. Conceptually it is possible to actually
physically conduct a process that keeps the entropy of the system constant,
allowing systematically controlled removal of heat, by conduction to a cooler
body, to compensate for entropy produced within the system by irreversible
work done on the system. Such isentropic conduct of a process seems
called for when the entropy of the system is considered as an independent
variable, as for example when the internal energy is considered as a
function of the entropy and volume of the system, the natural variables of the
internal energy as studied by Gibbs.
“
6. “
Isenthalpic process:
occurs at a constant
enthalpy
Isolated process: no
matter or energy
(neither as work nor as
heat) is transferred into
or out of the system
“
7.
8. A thermodynamic cycle is a series of thermodynamic processes which returns
a system to its initial state. Properties depend only on the thermodynamic
state and thus do not change over a cycle. Variables such as heat and work
are not zero over a cycle, but rather depend on the process. The first law of
thermodynamics dictates that the net heat input is equal to the net work output
over any cycle. The repeating nature of the process path allows for continuous
operation, making the cycle an important concept in thermodynamics.
Thermodynamic power cycles are the basis for the operation of heat engines,
which supply most of the world's electric power and run almost all motor
vehicles. Power cycles can be divided according to the type of heat engine they
seek to model. The most common cycles that model internal combustion
engines are the
10. The Otto cycle efficiency becomes
th Otto
T
T
, 1 1
2
Since process 1-2 is isentropic,
1
2 1
1 2
1 1
1 2
2 1
1
k
k k
T V
T V
T V
T V r
where the compression ratio is
r = V1/V2 and th Otto k
r
,
1
1
1
11. Thermodynamic Cycle
Otto and Diesel Cycle
Engines working on Otto and diesel cycle in an automoblibe
although form in a cycle, are not reversible cycle as the working
medium changes changes after each cycle. Otto and diesel are
much similar to each other except the heat addition process. In otto
heat addition is by constant volume process where as in diesel the
heat addition is by constant pressure process. These cycles are not
as efficient as carnot cycle as process are not reversible
12. Applications of Thermodynamics
Thermodynamics in common usage in engineering is the study of energy and
its various interconversions from one form to another. Thermodynamics has
several types of Applications in our daily life: Fossil-fueled steam power
plants, Spark-ignition engines and Jet engines .All types of vehicles that we
use, cars, motorcycles, trucks, ships, aero planes, and many other types work
on the basis of second law of thermodynamics and Carnot Cycle.
13. No Questions Please
ou
r
off
ice
Thermodynamics is not the study of heat
and work alone. Thermodynamics is the
study of the dynamics and behavior of
energy and its manifestations. Energy is
the only thing that keeps things going.
You are energy.
You are thermodynamics.
