Introduction of thermodynamics Chapter- 1

Introduction of thermodynamics

It is a branch of applied science, which involves the study of energy its form and transformation and its interaction with matters. It has a many application such as heat engines , heat pump , petrol engine, heat exchanger, nozzle, turbine, fan, pump, compressor etc.

Value of energy in society:

  1. Basic requirements of life.
  2. Simplicity of life.
  3. Increase reliability and versatility of machines.
  4. Energy consumption pattern of any country reflects in lifestyle(living condition)

Difference between microscopic and macroscopic viewpoint:

Microscopic viewpoint Macroscopic viewpoint
System is analyzed reference to its molecular structure or molecular behavior. System is analyzed with reference of certain measurable and observable properties.
It involves large number of variables. It contains less number of variables.
It is difficult and time consuming. It is easy simpler and faster.
It is used by pure scientists. It is used by engineer.
It is used in pure thermodynamics. It is used in applies thermodynamics.
Eg: volume of room = volume of one molecule * total number of molecule Eg: volume of room= length * breadth * height

Thermodynamics system, surrounding, boundary and universe:

It is system which is analyzed by the thermodynamics viewpoint is called thermodynamics system.

Everything outer of system is called surrounding.

The medium which separates the system and surrounding is called boundary.

A system and surrounding is together called universe.

Mode  of interaction between system and surrounding there are three types of system:

  1. Open system: the system which transfer a mass and energy system to surrounding is called open system. It is also called control volume. Eg: turbine, compressor etc.
  2. Closed system: the system which transfer energy system to surrounding but not mass called closed system. It is also known as control mass. Eg:piston cylinder device.
  3. Isolated system: the system which neither transfer mass nor energy called isolated system. Eg: thermo- flask ,universe etc.

Thermodynamic properties:

Any parameter or variable which are used to describe a thermodynamic system is called thermodynamic properties. Eg: pressure,temperature, volume, entropy, enthalpy etc. there are two types of thermodynamic properties that is given below:

Intensive properties:

Thermodynamic properties which are independent on a part of extent or extent of mass of a system is called intensive properties. Eg: pressure, temperature etc.

Extensive properties:

Those thermodynamic properties which are dependent of extent of mass or extent of pare are called extensive properties. Eg: temperature, entropy, enthalpy etc. extensive properties per unit mass called specific properties. Eg: specific volume(v), specific entropy(s) etc. where v=V/m and s=S/m.

Properties of thermodynamic properties:

  1. Variable is a thermodynamic properties if and only if it has single value at each equilibrium state.
  2. Variable is a thermodynamic properties if and only if it changes its value between two prescribed state independent of path.

Difference between path and state function:

State/ point function Path function
Variable which depends on a end state. Variable which independent on a end state or depend on a path.
They are thermodynamic properties. They are not thermodynamic properties.
Cyclic integral of function is zero. Cyclic integral of function is not zero.
They have exact differential. They have inexact differential.
Eg: temperature, pressure etc Eg: heat and work.

Thermodynamic equilibrium:

A system is said to be the thermodynamic equilibrium if it has no change in any properties of system when it is isolated from surrounding. It is also defined as it has same value of intensive properties throughout the system. There are three types of thermodynamic equilibrium:

Chemical equilibrium: a system is a chemical equilibrium if there should not be any chemical reaction during the observation interval.

Thermal equilibrium:  a system is a thermal equilibrium if there should not be any temperature difference within a system.

Mechanical equilibrium: a system is a mechanical equilibrium if there should not be any pressure difference within a system.

Thermodynamic state:

Each unique condition in a thermodynamic system is called thermodynamic state.

Thermodynamic process:

Path fallowed by system which undergoes from one equilibrium state to another equilibrium state is called thermodynamic process. Eg: p-v diagram, T-S diagram, P-T diagram, T-V diagram.

Reversible process:

Any process which passes from series of equilibrium state such that each intermediate state is located on a property diagram is called reversible process. It is represented by continuous line.

Irreversible process:

Any process which passes through series of intermediate state which cannot be located on a property diagram is called irreversible process. It is represented by broken line.

Quassi static process:

To make the process completely reversible infinite number of blocks having very small weights are using such process are called quassi static process.

Cyclic process:

A process is said to be cyclic process if initial state of the system is restored by number of different process in series is called cyclic process.

Equality of temperature:

Two system is said to have a equal temperature if and only if no change in any properties of both system when they are brought in contact with each other.

Zeroth law of thermodynamic:

When two system are thermal equilibrium with third system separately then two system also a thermal equilibrium each other. It is called zeroth law of thermodynamics. It has used to measure a temperature of multiple objects.

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