Types of Thermodynamic Systems
There are three mains types of system: open system, closed system and isolated system. All these have been described below:
1) Open system: The system in which the transfer of mass as well as energy can take place across its boundary is called as an open system. Our previous example of engine is an open system. In this case we provide fuel to engine and it produces power which is given out, thus there is exchange of mass as well as energy. The engine also emits heat which is exchanged with the surroundings. The other example of open system is boiling water in an open vessel, where transfer of heat as well as mass in the form of steam takes place between the vessel and surrounding.
2) Closed system: The system in which the transfer of energy takes place across its boundary with the surrounding, but no transfer of mass takes place is called as closed system. The closed system is fixed mass system. The fluid like air or gas being compressed in the piston and cylinder arrangement is an example of the closed system. In this case the mass of the gas remains constant but it can get heated or cooled. Another example is the water being heated in the closed vessel, where water will get heated but its mass will remain same.
3) Isolated system: The system in which neither the transfer of mass nor that of energy takes place across its boundary with the surroundings is called as isolated system. For example if the piston and cylinder arrangement in which the fluid like air or gas is being compressed or expanded is insulated it becomes isolated system. Here there will neither transfer of mass nor that of energy. Similarly hot water, coffee or tea kept in the thermos flask is closed system. However, if we pour this fluid in a cup, it becomes an open system.