Thermodynamic is the branch of the mechanical engineering which is deals with heat, work, and temperature and also relation between them. Thermodynamic also concern with enery, radiation, and physical properties of the matter(you can learn all things using computer).
To study the matter thermodynamics gives you the four law of thermodynamic which is the application of thermodynamic. Thermodynamic used in the variety of the topic in the science and engineering. Also thermodynamic used in the physical properties , chemical properties , chemical engineering , mechanical engineering, and also in the other field . So the use of thermodynamic is verstile which means the importance of the thermodynamic is very crucial .
In earlier days , thermodynamic is used to increase the efficiency of the steam engine . French physicist Nicolas leonard sadi carnot (1854) believed that the engine efficiency was the main key that could help french win the Napoleonic wars. Scots-irish physicist lord kelvin was the first physicist to develope the formulation of the thermodynamic in 1854.
Which state that ” thermodynamics is the subject of the relation of the heat to forces acting between contiguous parts of bodies and the relation of the heat to the eletrical agency” .
The earier application of the thermodynamics to mechanical heat engines was quickly is used to study of the chemical componds and chemical reactions . Chemical thermodynamic studies the nature of entropy in the process of expansion and the khownledge of the field . So the other formulation of thermodynamics include , ” statistical thermodynamics and statistical mechanics concern itself with statistical predication of the collective motion of particales .
In 1909 , constanten caratheodory present purely mathematical approach in an aximatic formulation so called as geomaterial themodynamic.
Content
1) Introduction of thermodynamics
2) History
3) Branches of thermodynamics
4) Laws of thermodynamics
5) system models
6) states and processes
7) conjugate variables
8) potentials
Introduction of thermodynamics
In thermodynamics system , Four law of thermodynamics which forms that aximatic basis . The first law of thermodynamics state that energy can be transfer from one form of energy to the another form of energy by using heat and work .
The second law state that energy can be transfer from upper sink to lower sink to producing work and also state that energy can be transfer from lower sink to upper sink by consuming work . The second law define entropy .
In thermodynamic , intereaction between surrounding and system is studied . System called as particle or object and surrounding called atmosphere through this we can studied the properties of the system (e.g particles). So internal energy and thermodynamics potential is used to determine condition of equilibrium and spontaneous process.
Using this type of application of thermodynamics , we can determine the respond of the system during change in the environments . Thermodynamics applied variety of applications such as the engine, phase transitiors , chemical relations , transportions , black holes .
It also used in the following applications such as physicals , chemistry , chemical engineering , corrosion engineering , mechanical engineering , cell biology, biomedical engineering , material science and economics .
This article anly focus on the basic priciple of thermodynamics like system ,entropy , thermodynamics equilibrium and non-equilibrium.
Branches of thermodynamics
Thermodynamic systems has several related branches, each of branches uses a different fundamental model as a theoretical analyzed method or experimental basis method. The principles to varying types of systems.
Classical thermodynamics means the states of thermodynamic systems at nearly equilibrium, so the classical thermodynamic that uses macroscopic method to measure properties. Classical thermodynamics is used to exchanges of energy, work and heat based on the laws of thermodynamics . The subject developed in the 19th century and discover the changes of a system in terms of macroscopic (large scale, and measurable) parameters. A microscopic interpretation of these concepts was developed by statistical mechanics.
Statistical mechanics, also called statistical thermodynamics, atomic and molecular theories was devepoled in the late 19th century and early 20th century. Classical thermodynamics with an interpretation of the microscopic interactions between individual particles or quantum-mechanical states. Statistical mechanics field relates the microscopic properties of individual atoms and molecules to the macroscopic, bulk properties of materials can be observed by this method so classical thermodynamics as a natural result of statistics, classical mechanics, and quantum theory at the microscopic level.
Chemical thermodynamics is branch of thermodynamics which show that interrelation of energy with chemical reactions and physical change in state with discovered by the laws of thermodynamics.
Equilibrium thermodynamics is discovered matter and energy can be transfer into systems or bodies that, during surroundings, matter and energy can transfer from one state of thermodynamic equilibrium to another. Thermodynamic equilibrium indicates a state of balance, in which all macroscopic moments are zero. Equilibrium means intensive properties of body or system are homogeneous, and system or body pressures are perpendicular to their boundaries. In an equilibrium state , there are no unbalanced potentials and driving forces, between macroscopically distinct parts of the system. Equilibrium thermodynamics is given a system in a well-defined initial equilibrium state, and given its surroundings, and given its constitutive walls.
Non-equilibrium thermodynamics is a branch of thermodynamics which deals with systems they are not in thermodynamic equilibrium. Lots of systems found in nature which are not in thermodynamic equilibrium because system are not in stationary states . And these system continuously and discontinuously subject to flux of matter and energy to and from other systems. Non-equilibrium systems requires more fundamental concepts than are dealt with by equilibrium thermodynamics. Many natural systems still today remain beyond the scope of currently known macroscopic thermodynamic methods.
Laws of thermodynamics
Basically Thermodynamics is based on four laws which are valid to universally , when this four law applied on the systems that fall within the constraints. In thermodynamic descriptions , these laws may be expressed in differents forms, but the most prominent formulations are the following.
Zeroth Law
The zeroth law of thermodynamics states :
If two systems are thermal equilibrium to each other. so third system are also in thermal equilibrium with them.
This statement state that thermal equilibrium is an equivalence relation on thermodynamic systems under consideration. These thermodynamic Systems are said to be in equilibrium if the small, random exchanges between them .means that temperature of two
System is similer to third system and do not lead to a net change in energy. This law is used in every measurement of temperature. Thus, if to decide whether two bodies are at the same temperature, then bring them into contact and measure any changes of their observable properties in time . The law provides a definition of temperature, and also
show the law for the construction of practical thermometers.
The zeroth law did not initially recognized , its basis in thermodynamical equilibrium was implied in the other laws. The first, second, and third laws had been explicitly stated already, and we got acceptance in the physics community before the importance of the zeroth law for the definition of temperature was realized. it was named the zeroth law.
First Law of thermodynamic
The first law of thermodynamics states:
In a process, the change in internal energy, ΔU with constant matter of a thermodynamic system is equal to the energy gained as heat, Q, less the thermodynamic work, W, done by the system on its surroundings.
U=Q-W
In this processes, matter can be transfer , further statement is needed. when two systems, which may be different chemical compositions, which initially separated by an impermeable wall, and otherwise system is isolated. These system are combined into a new system by the thermodynamic operation of removal of the wall, then
U = U1 +U2
where U0 denotes the internal energy of the combined system, and U1 and U2 denote the internal energies of the respective separated systems.
this law is an expressed by the principle of conservation of energy, which states that energy cannot be created nor be distroyed it can transfer from one form of energy to another form of energy .
So Internal energy is a property of the thermodynamic state, while heat and work are modes of energy transfer by process may change this state. A change of internal energy of a system may be occured by any combination of heat added or removed and work performed on or by the system is called as change in internal energy . the internal energy does not depend on the path through intermediate steps, by which the system in its state position.
Second law of thermodynamics
The second law of thermodynamics states: Heat cannot spontaneously flow from a colder body to a hotter body.
This law is state that the universal principle of decay observable in nature. Differences in temperature, pressure, and chemical potential tend to even out in a physical system that is isolated from the outside world by this law. Entropy is used to measure of how much change in the process has progressed.
The entropy of an isolated system which is not in equilibrium state so entropy will tend to increase over time, approaching a maximum value at equilibrium. One of such principles is the maximum entropy production principle. So It states that non-equilibrium systems behave such a way as to maximize its entropy production.
In classical thermodynamics, the second law is a basically applicable to any system involving heat energy transfer. In statistical thermodynamics, the second law is a consequence of the assumed randomness of molecular chaos. There are many versions of the second law, but they all have the same effect, which is to express the phenomenon of irreversibility in nature.
Third Law of thermodynamics
The third law of thermodynamics states:
As the temperature of a system reaches to absolute zero, all processes and the entropy of the system also reach to the a minimum value.
Third law of thermodynamics is a statistical law of nature regarding entropy and the impossible to reach absolute zero of temperature. This law used to determine entropy of a system. The entropy determined relative to this point is the absolute entropy. Alternate definitions include “the entropy of all systems and of all states of a system is smallest at absolute zero,” or equivalently “it is impossible to reach the absolute zero of temperature by any finite number of processes”.
System models
System model is a important concept in thermodynamics. In the thermodynamic system, which is a defined everything in the universe except the system is called the surroundings. system and surrounding is separated by a boundary which may be a physical or imaginary , system has finite volume. Boundary are described as walls; they have respective defined ‘permeabilities’. Transfers of energy(work, heat, mass) between the system and the surroundings, take place through the boundary.
If Matter or energy of system that pass through the boundary this effect cause change in the internal energy of the system for energy is balance by this system models . The body of steam or air in a steam engine, such as Sadi Carnot defined in 1824.
Boundaries has a four types, they may be fixed, movable, real, and imaginary. E.g, In an engine, a fixed boundary means the piston is locked at its position, within which a constant volume process might occur. If the piston is allowed to move that boundary is movable while the cylinder and cylinder head boundaries are fixed.
For closed systems, boundaries are real while for open systems boundaries are often imaginary. In the case of a jet engine, a fixed imaginary boundary might be assumed at the intake of the engine, fixed boundaries along the surface of the case and a second fixed imaginary boundary across the exhaust nozzle.
Generally, thermodynamics distinguishes three classes of systems, defined in terms of what is allowed to cross their boundaries.
States and processes
When a system is at equilibrium state with a certain conditions, so the system is in a definite thermodynamic state. The state of the system can be formed by a number of state quantities which doesnot depend on the process in which the system reach at its state. They are two properties called intensive properties or extensive properties. According to change in properties when the size of the system changes. The properties of the system can be form by an equation of state which specifies the relationship between these properties.
Several commonly studied thermodynamic processes are:
Adiabatic process: this process occurs without loss or gain of energy by heat, this process occurs at a constant enthalpy
Isentropic process: this process is a reversible adiabatic process, which occurs at a constant entropy
Isobaric process: this process occurs at constant pressure
Isochoric process: this process occurs at constant volume (also called isometric/isovolumetric)
Isothermal process: this process occurs at a constant temperature
Steady state process: this process occurs without a change in the internal energy
Conjugate variables
The important concept of thermodynamics is that of energy, the ability to do work by using energy and thermodynamics principles. By the First Law, the total energy of a system and its surroundings is conserved. Energy can be transferred into a system by heating, compression, or addition of matter, and so extracted happen from a system by cooling, expansion, or extraction of matter. In mechanics, e.g energy transfer is to equals the product of the force applied to a body and displacement of the product.
Conjugate variables are pairs of thermodynamic concepts, e.g force applied to any thermodynamic system, and then displacement of the system occurs and the product of the two equaling the amount of energy transferred.
The common conjugate variables are:
Pressure-volume
(the mechanical parameters);
Temperature-entropy (thermal parameters);
Chemical potential-particle number (material parameters).
Potentials
Thermodynamic potentials are different from other concept of thermodynamics . Potentials is used to measures of the stored energy in a system. Potentials are used to measure the energy changes in systems during initial state to a final state. The potential used depends on the constraints of the system, e.g constant temperature or pressure. For example, the Helmholtz and Gibbs energies are the energies available in a system to do useful work when the temperature and volume or the pressure and temperature are fixed, respectively.