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Adiabatics with OTTO CYCLE

  • #1
hey guys, just wanted to know, in the graph of the OTTO cycle in the link

http://www.qrg.northwestern.edu/thermo/design-library/otto/Otto-Pv-diagram.gif

are stage (2-3) and (1-4) adiabatic or not, if so why are they

the reason i ask is that i have a graph showing that these stages are adiabatic, however, adiabatic processes are where no heat is exchanged QIN = 0
 

Answers and Replies

  • #2
kuruman
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Adiabatic and isentropic are one and the same thing. The adiabats on your diagram are 1-2 and 3-4. The other two, 2-3 and 1-4 are isochoric (constant volume).
 
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  • #3
Andrew Mason
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Adiabatic and isentropic are one and the same thing.
Isentropic processes are always adiabatic. Adiabatic processes, however, are not always isentropic. A non-isentropic adiabatic process, such as free expansion of a gas, should not be referred to as adiabatic, in my view. However, I seem to have lost that battle.

AM
 
  • #4
kuruman
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Isentropic processes are always adiabatic. Adiabatic processes, however, are not always isentropic. A non-isentropic adiabatic process, such as free expansion of a gas, should not be referred to as adiabatic, in my view. However, I seem to have lost that battle.

AM
Thanks for pointing out the subtle difference. I should have confined myself to answering the original question instead of trying to generalize.
 

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