In an adiabatic throttling process of ideal gas:

I understand that mathematically lost work is given by Tsurr * entropy generated.

But intuitively I can't understand if there is not heat exchange between system and surroundings how can the temperature of surrounding affect the work obtained by system.

  • $\begingroup$ adiabatic means no heat exchange so you assume a perfect system. $\endgroup$
    – Solar Mike
    Sep 15, 2018 at 9:13
  • $\begingroup$ You have the cart before the horse as the saying goes. Systematic analysis gives understanding. Intuition supports it. Do you have an example of your analysis? Can you show a picture of the system, define all variables, and state the governing equations. $\endgroup$ Sep 15, 2018 at 14:34
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    $\begingroup$ @SolarMike I have never seen a proof that an adiabatic process means a perfect system (whatever "perfect system" means). I am curious to see yours. $\endgroup$ Sep 15, 2018 at 14:36
  • $\begingroup$ @JeffreyJWeimer is that how theoretical systems are solved then we adjust for reality... if not how can we “solve” for turbulent flow ie the Navier-Stokes equations without makng loads of assumptions... $\endgroup$
    – Solar Mike
    Sep 15, 2018 at 15:44
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    $\begingroup$ I do not doubt that we make assumptions. I doubt that an adiabatic process means a perfect system, and in any case the term "perfect system" has no coherent, unambiguous, consistent meaning to define systems in thermodynamics. $\endgroup$ Sep 15, 2018 at 17:02

1 Answer 1


If the system is isolated, Tsurr not going to affect.

If the system is isolated, (no mass and energy transfer between the system and the surrounding ) then the work could be extracted from the system will be still less than what it contains in terms of energy. This is due to the irreversible path of the work extraction from the system.

To calculate how much work could be extracted from the system, you could do exergy (not energy) analysis.


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