- Asked 2/15
- 2069 Bhadra · 5 marks
- 2069 Poush · 5 marks
Closed system vs open system
Short answer
A closed system (control mass) allows only energy transfer across its boundary, e.g., sealed piston-cylinder. An open system (control volume) allows both mass and energy transfer, e.g., turbine. An isolated system permits neither, e.g., an idealized thermos flask.
Explain different types of thermodynamic systems and differentiate between them with examples.
A thermodynamic system is a definite quantity of matter or a region in space chosen for study. Everything outside it is the surroundings, and the real or imaginary surface between them is the boundary. Systems are of three types.
1. Closed system (control mass)
No mass crosses the boundary, but energy (heat and work) can. The mass is fixed. Example: gas in a piston-cylinder device with the valve closed; a sealed pressure cooker before venting.
2. Open system (control volume)
Both mass and energy can cross the boundary. The boundary is the control surface and the region is fixed in space. Example: turbine, compressor, nozzle, boiler, a water pump.
3. Isolated system
Neither mass nor energy crosses the boundary. Example: a perfectly insulated and sealed thermos flask (ideal); the universe as a whole.
Closed Open Isolated
+--------+ +----------+ +----------+
| fixed | | mass in->| | no mass |
| mass | | ->out | | no heat |
+--------+ +----------+ +----------+
Q,W cross m, Q, W cross nothing crosses
| Basis | Closed system | Open system |
|---|---|---|
| Mass transfer | Not allowed | Allowed |
| Energy transfer | Allowed (Q, W) | Allowed (Q, W, flow energy) |
| Also called | Control mass | Control volume |
| Boundary | Moving or fixed | Usually fixed (control surface) |
| Examples | Gas in closed cylinder | Turbine, compressor, nozzle |
✓ Answer checked by Claude Opus 5.5 (high effort)
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