Engineering Thermodynamics: Work And Heat Transfer

Where:

| Aspect | Work | Heat | |--------|------|------| | Driving potential | Force (pressure, torque, voltage) | Temperature difference | | Mechanism | Macroscopic, directional | Microscopic, random | | Convertibility to work | 100% convertible (in principle) | Limited by Carnot efficiency | | System boundary requirement | Often requires moving boundary or shaft | Requires temperature gradient | | Path dependence | Yes (area under ( p-V ) curve) | Yes (area under ( T-S ) curve) | engineering thermodynamics work and heat transfer

They are not properties of a system. You cannot look inside a pressure cooker and say, "This contains 50 joules of heat." You can only say, "Heat transferred into the cooker." Once the energy crosses the boundary, it becomes part of the system’s internal energy. Where: | Aspect | Work | Heat |