REVIEW OF THERMODYNAMICS CYCLES RELATED TO POWER PLANTS
Thermodynamics is the
science of many processes involved in one form of energy being changed into
another. It is a set of book keeping principles that enable us to understand
and follow energy as it transformed from one form or state to the other.
The zeroth law of
thermodynamics was enunciated after the first law. It states that if two bodies
are each in thermal equilibrium with a third, they must also be in thermal
equilibrium with each other. Equilibrium implies the existence of a situation
in which the system undergoes no net charge, and there is no net transfer of
heat between the bodies.
The first law of
thermodynamics says that energy can?t be destroyed or created. When one energy
form is converted into another, the total amount of energy remains constant. An
example of this law is a gasoline engine. The chemical energy in the fuel is
converted into various forms including kinetic en-ergy of motion, potential
energy, chemical energy in the carbon dioxide, and water of the exhaust gas.
The second law of
thermodynamics is the entropy law, which says that all physical processes
proceed in such a way that the availability of the energy involved decreases.
This means that no transfor-mation of energy resource can ever be 100%
efficient. The second law declares that the material economy necessarily and
unavoidably degrades the resources that sustain it. Entropy is a measure of disorder
or chaos, when entropy increases disorder increases.
The third law of
thermodynamics is the law of unattainability of absolute zero temperature,
which says that entropy of an ideal crystal at zero degrees Kelvin is zero. It?s
unattainable because it is the lowest temperature that can possibly exist and
can only be approached but not actually reached. This law is not needed for
most thermodynamic work, but is a reminder that like the efficiency of an ideal
engine, there are absolute limits in physics.
The steam power plants
works on modified rankine cycle in the case of steam engines and isentropic
cycle concerned in the case of impulse and reaction steam turbines. In the case
of I.C. Engines (Diesel Power Plant) it works on Otto cycle, diesel cycle or
dual cycle and in the case of gas turbine it works on Brayton cycle, in the
case of nuclear power plants it works on Einstein equation, as well as on the
basic principle of fission or fusion. However in the case of non-conventional
energy generation it is compli-cated and depends upon the type of the system viz., thermo electric or thermionic
basic principles and theories et al.