Basic Concepts in Thermodynamics

Construction of Simple Premises …..

P M V SubbaraoProfessor

Mechanical Engineering Department

I I T Delhi

Albert Einstein`s Definition of Best Theory

• A Theory is more impressive /useful

– the greater the simplicity of its premises is,

– the more different kinds of things it relates,

– and the more extended is its area of applicability.

Therefore, the deep impression which Classical Thermodynamics made upon me.

It is only physical theory of universal content concerning which I am convinced that ,

within the framework of the applicability of its basic concepts, it will never be overthrown.

A Thermodynamic System

A thermodynamic system is a collection of matter which has distinct boundaries.OR

A real or imaginary portion of universe which has distinct boundaries is called system.OR

A thermodynamic system is that part of universe which is under thermodynamic study.

Thermodynamic System and Surroundings

System: the material in a portion of space whose thermodynamic study is to be made

Surroundings: Everything exterior to the system

Boundary: A separator, real or imaginary, between system and surroundings.

Basis for Classification of Thermodynamic Systems

• Nature of interaction with its surroundings.

• Mass interactions.

• Momentum & Energy Interactions.

• Species Interactions.

Classification of Thermodynamic Systems : Mass Interactions.

Control Mass (Closed system): fixed mass (solid or fluid) within the boundary.

Control Volume :(Open (flow) system): A volume with partly solid boundaries and imaginary boundary sections through which fluid moves

Conjugate Systems : Timed switching from CM to CV or CV to CM

Manufacturing System as a Control Mass or Control Volume

• Case study : Fabrication of ceramic products

• Most popular process : Sintering

Sintering (Firing) of ceramic materials is the method involving consolidation of ceramic powder particles by heating the “green” compact part to a high temperature below the melting point, when the material of the separate particles diffuse to the neghbouring powder particles.

Sintering System : Control Mass

Continuous Sintering System : Control Volume

Continuous Sintering System : Control Volume

Momentum Interactions….

Also facilitate Energy transactions ….

Isolated system

Isolated system: An isolated system is one that is not influenced in any way by the surroundings.

A Control Mass through which no heat interactions and which does no work interactions (rigid).

This means that no mass, heat, or work cross the boundary of the system.

Adiabatic Control Mass

Adiabatic Control Mass : A control mass through which no heat interactions with surroundings but can do other actions equivalent to work.

Adiabatic control volume

A Control Volume which has no heat interactions, but can have work interactions.

Second Level Thermodynamic Analysis

•In a solid is heated, strains and stresses develop.•Conversely if body is strained rapidly, then heat is generated inside the body.•The changes undergone by this system can be characterized by some functions.•What kind functions can be used for correct recognition of these changes.