Max efficiency (thermodynamics)

  • Thread starter pinsky
  • Start date
  • #1
96
0
I'm observing the circular process of a heat engine. It's p-v diagram is

heaengcyc.gif


So between points 3 and 4 the heat is extracted. That causes losses since the efficiency if given by
[tex] \eta =1- \frac {Q_c} {Q_h} [/tex]

Where Qh is the heat the heat source has given and Q_c the amount of heat that the "cold" container took.
If we don't cool down the engine in during the process between 3 and 4, the efficiency would grow to 100% (if friction is not consigered).
The process would then look like the picture below, and 3 and 1 we would do an isobaric contraction.

attachment.php?attachmentid=24297&stc=1&d=1268325038.gif


I've encountered isobaric processes through my studies, but only as a theoretical concept. What are the reasons why it couldn't be used here?
 

Attachments

  • why_not_thermodynamics.gif
    why_not_thermodynamics.gif
    2.8 KB · Views: 427

Answers and Replies

  • #2
QuantumPion
Science Advisor
Gold Member
902
42
How can you do compress the working fluid without changing its pressure or temperature?
 
  • #3
96
0
I don't know, how do you get an isobaric process ever? :)
 

Related Threads on Max efficiency (thermodynamics)

Replies
4
Views
1K
Replies
2
Views
742
Replies
10
Views
15K
Replies
8
Views
7K
  • Last Post
Replies
11
Views
3K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
2
Views
617
  • Last Post
Replies
3
Views
4K
  • Last Post
Replies
4
Views
2K
Top