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Polytropic Process

A polytropic process is any thermodynamic process that can be expressed by the following equation:

pVn = constant

The polytropic process can describe gas expansion and compression, which include heat transfer. The exponent n is known as the polytropic index, and it may take on any value from 0 to ∞, depending on the particular process.

There are some special cases of n, which corresponds to particular processes:


  • the case 1 < n < , in this process, heat and workflows, go in opposite directions, This process occurs, for example, in vapor compression refrigeration during compression
  • the case < n <, in this process, heat and workflows go in the same direction, This process occurs, for example, in an internal combustion engine (e.g.,, Otto cycle), in which there are heat losses through the cylinder walls during a gas expansion (power stroke).
Polytropic process - main characteristics
Polytropic process – main characteristics

For a polytropic process between two states:


p1V1n = p2V2n

polytropic process - pv diagram
Polytropic processes with various polytropic indexes.


Nuclear and Reactor Physics:
  1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
  2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
  3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
  4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
  5. W.S.C. Williams. Nuclear and Particle Physics. Clarendon Press; 1 edition, 1991, ISBN: 978-0198520467
  6. Kenneth S. Krane. Introductory Nuclear Physics, 3rd Edition, Wiley, 1987, ISBN: 978-0471805533
  7. G.R.Keepin. Physics of Nuclear Kinetics. Addison-Wesley Pub. Co; 1st edition, 1965
  8. Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.
  9. U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.

Advanced Reactor Physics:

  1. K. O. Ott, W. A. Bezella, Introductory Nuclear Reactor Statics, American Nuclear Society, Revised edition (1989), 1989, ISBN: 0-894-48033-2.
  2. K. O. Ott, R. J. Neuhold, Introductory Nuclear Reactor Dynamics, American Nuclear Society, 1985, ISBN: 0-894-48029-4.
  3. D. L. Hetrick, Dynamics of Nuclear Reactors, American Nuclear Society, 1993, ISBN: 0-894-48453-2. 
  4. E. E. Lewis, W. F. Miller, Computational Methods of Neutron Transport, American Nuclear Society, 1993, ISBN: 0-894-48452-4.

See above:

Thermodynamic Processes