Thermodynamic system

A system is a group of things.

It can be in a box. The walls of the box change how it works.

One box is an open system. Things and heat can move in and out.

Another box is a closed system. Heat can move through the walls. But the things inside stay inside.

A third box is an isolated system. Nothing can move in or out. It stays the same for a long time. This is called being in balance.

Systems can also change energy. Some systems just move energy around. Other systems change one kind of energy into another. It is fun to see how they work!

A thermodynamic system is a group of matter or energy.

It is separate from everything else around it. We call the space outside the system the surroundings.

The walls of the system decide what can move in or out.

There are three main types of systems. An open system lets both matter and energy move through its walls. A closed system lets energy move, but keeps the matter inside. An isolated system is different. It does not let any matter or energy pass through.

Systems can also act in two ways. Passive systems just move energy around. For example, heat might move from a warm end to a cold end. Active systems change one type of energy into another. This can happen in a motor or a chemical reaction.

Sometimes, a system reaches a state called thermodynamic equilibrium. This means the system is in balance. At this point, things like heat and pressure stop changing. The system stays steady over time. In nature, things are rarely in perfect balance. However, thinking about balance helps us study how the world works.

A thermodynamic system is a group of matter or energy. It is kept separate from everything else around it. We call the space outside the system the surroundings.

The system is defined by its walls or boundaries. These walls can be real objects like a metal container. They can also be imaginary lines used for study. The properties of these walls decide what can pass through. Some walls allow things to move, while others block them. This helps scientists study how energy and matter behave.

Systems are grouped by how they interact with their surroundings. An open system can exchange both matter and energy. A closed system can exchange energy, but it keeps its matter inside. It can experience forces or exchange heat. An isolated system is the most restricted type. It does not exchange any matter or energy with its surroundings.

In an isolated system, things eventually reach a stable state. This happens as internal changes slowly finish over time. Pressure and temperature will eventually become the same everywhere inside.

Scientists also look at how energy moves inside a system. A passive system only redistributes the energy it already has. For example, heat moves from a warm end to a cold end. This makes the temperature equal throughout the whole object. An active system is different because it converts energy. It changes one type of energy into another type. This can happen during chemical reactions or in a motor.

These active processes often push a system away from balance.

People have studied these ideas for a long time. Sadi Carnot from France studied heat engines in 1824. He looked at how steam or air works in engines. Later, Ilya Prigozhin from Belgium studied dissipative structures in 1971. In 2010, Boris Dobroborsky proposed a new way to classify systems. He divided them into passive and active systems based on energy.

These different ideas help us understand how the world works. They help us move from simple ideas to complex ones.

Understanding these systems helps us see how the world stays steady. Most things in nature are not in perfect balance. However, we use the idea of equilibrium to make helpful guesses. Equilibrium means there are no visible flows of matter or energy.

It is like a calm lake with no moving waves. When a system is in equilibrium, its properties do not change over time. This idea is a fundamental part of all thermodynamics. It allows us to study everything from tiny atoms to huge engines.

A thermodynamic system is a specific body of matter or radiation. It is separated from its surroundings by a boundary or a wall. Scientists study these systems to understand how energy and matter behave. The space outside the system is called the surroundings or the environment.

The properties of the walls determine what can pass between the system and its surroundings. These walls can be real, like a metal container. They can also be imaginary surfaces used for mathematical study. A wall might be fixed, like a constant volume reactor. It might also be moveable, such as a piston in an engine.

Thermodynamic systems are classified by how they interact with their environment. There are three main types based on the permeability of their walls. An open system allows both matter and energy to pass through its boundaries. A closed system allows energy to pass as heat or work, but it does not exchange matter.

An isolated system is the most restrictive type. It does not exchange any matter or energy with its surroundings. In practice, an isolated system is an idealization. Some transfer, such as through gravitational forces, is almost always possible in nature.

Internal processes allow for another way to categorize these systems. In 2010, Boris Dobroborsky proposed a classification based on how energy behaves inside. He identified passive systems and active systems. A passive system only redistributes its available energy. For example, if one end of a metal rod is warmer than the other, heat will transfer until the temperature is equal. An active system actually converts one type of energy into another. This occurs during chemical reactions or when an electric motor operates. Active processes often cause a system to move away from a state of balance.

Thermodynamic equilibrium is a central concept in this field of science. A system is in equilibrium when there are no macroscopic flows of matter or energy. This means there is no visible tendency toward change on a large scale. In such a state, the physical properties of the system do not change over time. For instance, pressures and temperatures will eventually equalize. Matter may also arrange itself into a few stable, homogeneous phases.

Equilibrium states are easier to describe using deterministic math than non-equilibrium states.

Scientists study two main branches of this subject. Equilibrium thermodynamics looks at bodies that are in a state of internal balance. It uses the concept of thermodynamic processes to describe how bodies move from one equilibrium state to another. This field relies on a well-defined quantity called entropy. Non-equilibrium thermodynamics is a more complex and growing field. It studies systems that are not in balance and involve the flow of matter and energy. These systems often have spatial gradients, such as a change in temperature over a distance. Because these systems are changing, it is difficult to find an exactly defined entropy for them.

History shows how our understanding of these systems has evolved. The study of thermodynamic processes began with early theories of heat engines. Sadi Carnot from France published work on this in 1824. Later, Ilya Prigozhin from Belgium studied dissipative structures in 1971. These studies focused on how systems interact with their surroundings. The classification of systems into open, closed, and isolated grew alongside the science itself. This progression has allowed us to model everything from tiny atoms to massive steam engines.

Understanding these systems is vital for many scientific and engineering tasks. In engineering, many processes are described as flow processes. These approximate equilibrium concepts to make practical calculations possible. Even though nothing in nature is in strict thermodynamic equilibrium, the idea is a very useful tool. It provides a way to create models and perform experiments. By using these idealizations, we can predict how energy will move and how matter will react in the real world.