Tuesday, February 8


Thermodynamics is the branch of science or physics that studies various forms of energies and their conversion from one form to the other like electrical energy to mechanical energy, heat to electrical, chemical to mechanical, wind to electrical etc. Thermodynamics is an important subject area studied under Mechanical Engineering.

Important laws of thermodynamics namely first law of thermodynamics, second law of thermodynamics, third law of thermodynamics and Zeroth law of thermodynamics.

System is the system of hot liquid water and solid table salt in a sealed, insulated test tube held in a vacuum (the surroundings). 

Open systems may exchange any form of energy as well as matter with their environment. A boundary allowing matter exchange is called permeable. The ocean would be an example of an open system.

Closed systems are able to exchange energy (heat and work) but not matter with their environment. A greenhouse is an example of a closed system exchanging heat but not work with its environment. Whether a system exchanges heat, work or both is usually thought of as a property of its boundary.

§  Adiabatic boundary – not allowing any heat exchange
§  Rigid boundary – not allowing exchange of work

Isolated systems are completely isolated from their environment. They do not exchange heat, work or matter with their environment. An example of an isolated system is a completely insulated rigid container, such as a completely insulated gas cylinder. As time passes in an isolated system, internal differences in the system tend to even out and pressures and temperatures tend to equalize, as do density differences. The second law of thermodynamics is only true for isolated systems. It is important to note that isolated systems are not equivalent to closed systems.

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