A polytropic process is a type of thermodynamic process that follows a specific relationship between pressure PP and volume VV of a gas, described by the equation: PVn=constantP V^n = \text{constant}
Here, nn is called the polytropic index, which can take any real value and characterizes the nature of the process.
Key points:
- If n=0n = 0, the process is isobaric (constant pressure).
- If n=1n = 1, the process is isothermal (constant temperature).
- If n=γn = \gamma (ratio of specific heats Cp/CvC_p/C_v), the process is adiabatic (no heat exchange).
- For other values of nn, the process is somewhere in between, involving heat transfer and work done.
Physical meaning:
- A polytropic process models many real-world processes where heat transfer occurs but not enough to be purely isothermal or adiabatic.
- It’s useful because it generalizes many processes into one formula and can describe compression or expansion of gases in engines, compressors, or turbines.
Would you like me to explain the derivation or some example applications?