Does hot air require more work to compress than cold air?

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Discussion Overview

The discussion centers on the question of whether hot air requires more work to compress than cold air. Participants explore the implications of temperature on the energy required for compression, considering both theoretical and practical aspects.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions whether hot air needs more energy to compress than cold air, seeking clarity on the relationship between temperature and compression work.
  • Another participant suggests using the ideal gas law (PV=nRT) to calculate the work needed for compression, indicating a theoretical approach to the problem.
  • A different participant asserts that warmer gas requires more power to compress at given pressure and flow rates, implying a direct relationship between temperature and energy requirements.
  • Further inquiry is made regarding whether the difficulty in compressing air is due to its proximity to absolute zero or if it is proportional to temperature changes, indicating a desire for deeper understanding.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between temperature and the work required for compression, with no consensus reached on the specifics of the underlying mechanisms.

Contextual Notes

The discussion involves assumptions related to ideal gas behavior and does not resolve the complexities of real gas behavior under varying temperature conditions.

Nabo00o
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Okey, simple question. As written in the title, I'm really not sure how this should work.
Should hot air need more energy to compress than cold air, is it the other way around or is there no difference?

This is asked because I need to find out if a physical system could work or not...
Any help appreciated!

Naboo
 
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Hi Nabo00o, welcome to PF. One way to tackle this is to assume ideality (i.e., PV=nRT) and calculate the work needed to compress the gas, \int -P\,dV. Does this help?
 
Yes, the warmer the gas, the more power needed to compress given any pressure inlet and outlet and flow rate.
 
@Mapes
Thank you Mapes.
Yes I think that will help me as soon as I understand the formula correctly.

@Q_Goest
Okey. But is this only because air closer to total zero is harder to expand, or is it more or less proportional with the change of temperature?
Sorry if this is a dumb question, I just need to understand it correctly.
 

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