Short Answer
The difference between an open system, closed system, and isolated system is based on how they exchange energy and matter with their surroundings.
An open system allows both energy and matter to move in and out, like a steam turbine or human body. A closed system allows only energy exchange but does not allow the transfer of matter, such as a piston-cylinder arrangement. An isolated system does not allow any exchange of energy or matter, like a thermos flask or the universe.
Detailed Explanation
Difference Between Open, Closed, and Isolated Systems
Thermodynamic systems are classified based on how they interact with their surroundings. The three types of thermodynamic systems—open, closed, and isolated systems—play an essential role in engineering applications.
- Open System
An open system is a system that exchanges both energy and matter with its surroundings. These systems involve a continuous flow of mass in and out, which makes them useful in various mechanical and industrial applications.
Characteristics of an Open System:
- Allows the transfer of both matter and energy.
- Found in systems where fluids or gases enter and exit continuously.
- Work and heat transfer occur along with mass flow.
Examples:
- Steam Turbines: Steam enters the turbine, performs work, and exits.
- Car Radiators: Hot coolant releases heat and exchanges mass with air.
- Human Body: Takes in food and oxygen, releases waste and heat.
- Closed System
A closed system allows only energy exchange, but not mass transfer. The mass inside remains constant, but heat or work can be transferred across the system boundary.
Characteristics of a Closed System:
- No mass transfer, only energy exchange.
- Found in systems where heat or work is transferred, but no material enters or exits.
- Common in mechanical and thermal systems requiring controlled environments.
Examples:
- Piston-Cylinder System: The gas inside expands or compresses without changing mass.
- Refrigerators: The refrigerant cycles within a closed loop, transferring heat.
- Pressure Cookers: Heat is added, but the mass remains constant unless the valve is opened.
- Isolated System
An isolated system does not allow any exchange of energy or matter with its surroundings. These systems are rare in real-world applications but serve as theoretical models in thermodynamics.
Characteristics of an Isolated System:
- No exchange of mass or energy.
- Used in cases where maximum insulation is needed.
- Theoretically ideal but difficult to achieve in practical applications.
Examples:
- Thermos Flask: Prevents heat transfer, keeping liquid hot or cold for long periods.
- The Universe: Considered an isolated system because no external matter or energy enters or leaves.
- Perfectly Insulated Containers: Used in scientific experiments to minimize energy loss.
Conclusion
The difference between an open system, closed system, and isolated system is based on how they exchange energy and matter. Open systems exchange both, closed systems exchange only energy, and isolated systems exchange neither. These classifications are fundamental in mechanical engineering for analyzing heat transfer, energy conservation, and system efficiency in power plants, refrigeration, and industrial processes.