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Thermodynamic processes in closed systems

Polytropic processes in a volume-pressure diagram

Polytropic process in a closed system

Learn more about polytropic thermodynamic processes in closed systems in this article. Particular processes shown in a volume-pressure diagram The figure below shows the course of the pressure as a function of the...
Summary of formulas and equations of polytropic processes

Derivation of the formulas for work and heat of a polytropic process

In this article you will learn more about the derivation of the formulas for calculating work, heat and change of internal energy for polytropic processes. Polytropic equations In the article Polytropic Process in...

Derivation of the formulas of the isentropic “adiabatic” process

In this article, learn more about the derivation of the formulas and equations describing the isentropic (adiabatic) process. Basic equations For the derivation of the equations describing the isentropic process, the first law...
Rapid changes of state in the cylinder of a combustion engine as an example of an approximate isentropic process

Isentropic (“adiabatic”) process in a closed system

An isentropic process is a reversible process of an adiabatic system. Definition Whereas in an isochoric process no pressure-volume work is done by the system or on the system (Wv=0) and in an...
Isothermal compression of the air in an air pump

Isothermal process in a closed system

In this article, learn more about the calculation of pressure, volume, work and heat in an isothermal process in a closed system. A change of state of a gas in which the...
Isobaric process by heating a gas-filled cylinder (constant pressure)

Isobaric process in a closed system

In this article, learn more about the calculation of volume, temperature, work, and heat in an isobaric process in a closed system. A change of state of a gas in which the...
Isochoric process by heating a gas bottle (constant volume)

Isochoric process in a closed system

In this article, learn more about the calculation of pressure, temperature, work and heat in an isochoric process in a closed system. A change of state of a gas in which the...
Phase diagram describing liquefaction of a real gas using carbon dioxide as an example

Explanation of liquefaction using the Van der Waals equation

In this article, learn how the Van der Waals equation can be used to explain the liquefaction of gases at high pressures. Van der Waals equation The ideal gas law describes the behavior...
Dissipation of energy by friction using the example of a toy car in a roller coaster

What is meant by dissipation of energy?

Dissipation is the (partial) conversion of a certain form of energy into thermal energy that cannot be fully converted back into the original form of energy. Definition Dissipation of energy means that when...
Conversion of heat into work

Concept of pressure-volume work (displacement work)

The pressure-volume work (displacement work) is the work don on the gas or by the gas due to the acting gas pressure during a change in volume. Heat engines and heat pumps Gases...
Energy flow diagram considering friction (dissipative process)

Dissipation of energy in closed systems

Learn in this article why, in thermodynamic processes with dissipation of energy, the pressure-volume work of the gas does not correspond to the work done by the system. Pressure-volume work (displacement work) In...
Considering a small change in volume at nearly constant pressure

Derivation of the pressure-volume work (displacement work)

Learn in this article why the area under the curve in a volume-pressure diagram corresponds to the pressure-volume work (displacement work). In the article concept of pressure-volume work, it was said without...
Experiment demonstrating the temperature increase during compression (adiabatic process)

Why do pressure and temperature increase during the compression of a gas?

The energy added as work during the compression of a gas leads to an increase in pressure and temperature. Learn more about this in this article. While an increase in temperature due...
Taking into account the attractive force between the molecules

Van der Waals equation (gas law for real gases)

The Van der Waals equation describes the relationship between pressure, volume and temperature for real gases. Ideal gas law In thermodynamic processes, gases are often considered as ideal gases for simplicity. Depending on...
Increasing the air temperature by doing work on the gas while inflating a bicycle tire with an air pump

Internal energy of ideal gases

In ideal gases, the change in internal energy is directly related to the change in temperature. Learn more about the relationships in this article. Simplified assumptions for ideal gases In thermodynamics, gases play...
Experiment to investigate the relationship between change of internal energy and temperature change in ideal gases

Calculation of the internal energy for ideal gases

Learn more about calculating the internal energy for ideal gases in this article. First law of thermodynamics In the article Internal energy of ideal gases it was explained in detail that in ideal...
Experiment to investigate the relationship between temperature and volume at constant pressure

Law of Gay-Lussac for ideal gases (Charles’s law)

The law of Gay-Lussac describes the relationship between an increase in temperature and the resulting increase in volume at constant pressure (isobaric process). Isobaric process If a thermodynamic process takes place at constant...
Experiment to investigate the relationship between pressure and temperature at constant volume

Law of Amontons for ideal gases

The law of Amontons describes the relationship between an increase in temperature and the resulting increase in pressure at constant volume (isochoric process). Isochoric process If a thermodynamic process takes place at constant...
Experiment to investigate the relationship between volume and pressure at constant temperature

Law of Boyle-Mariotte for ideal gases

The law of Boyle-Mariotte describes the relationship between a decrease in volume and the resulting increase in pressure at constant temperature (isothermal process). Isothermal process If a thermodynamic process takes place at constant...
Operating principle of a heat pump (conversion of work into heat)

The process quantities: Heat and work

Work and heat are process quantities that describe the process of a supply of energy ("energy in transit")! Learn more about it in this article. Work and heat transferred to a substance Energy...
Energy transfer done on a gas by heat and work (compression)

Internal energy & first law of thermodynamics

Internal energy is the sum of the different forms of energy on a microscopic level inside a substance. Learn more about it in this article. Energy transfer as heat and as work In...
Turbofan engine of an airplane

Thermodynamic systems

A thermodynamic system is a confined space of matter (e.g. gas) within which thermodynamic processes take place. The system boundary separates the system from the environment. Definition of the term thermodynamic system In...
Cylinder with a movable piston

Ideal gas law (explained and derived)

The ideal gas law describes the relationship between pressure, volume, mass and temperature of ideal gases. Parameters influencing the gas pressure The figure below shows a gas-filled cylinder closed with a piston. If...