An Introduction to Thermodynamics: Main Principles and Gas Laws

Compressed Air Wiki Thermodynamics Physics of Air Compressors Basic Theory

One very interesting branch of physics is thermodynamics, especially for getting insight in air compressors. This article tries to give you a short introduction to thermodynamics, discussing the main principles and Boyle’s and Charles’ gas laws.

What are the laws of thermodynamics?

Energy exists in various forms, such as thermal, physical, chemical, radiant (light etc.) and electrical energy. Thermodynamics is the study of thermal energy, i.e. of the ability to bring about change in a system or to do work.

The first law of thermodynamics expresses the principle of conservation of energy. It says that energy can be neither created nor destroyed, and from this, it follows that the total energy in a closed system is always conserved, thereby remaining constant and merely changing from one form into another. This, heat is a form of energy that can be generated from or converted into work.

The second law of Thermodynamics states that there is a tendency in nature to proceed toward a state of greater molecular disorder. Entropy is a measure of disorder: Solid crystals, the most regularly structured form of matter, have very low entropy values. Gases, which are more highly disorganized, have high entropy values. The potential energy of isolated energy systems that is available to perform work decreases with increasing entropy. The Second Law of Thermodynamics states that heat can never of "its own effort" transfer from a lower-temperature region to a higher temperature region.

Boyle’s and Charles’ gas laws

Boyle's law states that if the temperature is constant (isotherm), then the product of the pressure and volume are constant (formula)

Boyle's law states that if the temperature is constant (isotherm), then the product of the pressure and volume are constant.

Charles's law says that at constant pressure (isobar), the volume of a gas changes in direct proportion to the change in temperature (formula)

Charles's law says that at constant pressure (isobar), the volume of a gas changes in direct proportion to the change in temperature.

The general law of state for gases is a combination of Boyle's and Charles's laws. This states how, pressure, volume and temperature will affect each other. formula

The general law of state for gases is a combination of Boyle's and Charles's laws. This states how, pressure, volume and temperature will affect each other. When one of these variables is changed, this affects at least one of the other two variables.

The individual gas constant R only depends on the properties of the gas. If a mass m of the gas takes up the volume V, formula

The individual gas constant R only depends on the properties of the gas. If a mass m of the gas takes up the volume V, the relation can be written:

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