Heat Cycles, Work, and Efficiency

AI Thread Summary
The discussion focuses on calculating work and efficiency in a thermodynamic process. The initial attempt to use W=-∫PdV resulted in confusion regarding the correct integration method. Participants suggest using the integral of PdV consistent with the provided diagram for accurate results. One participant calculated work as W=2P1V1, leading to an efficiency of 17%. The conversation emphasizes the importance of proper integration techniques in thermodynamic calculations.
Marcin H
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Homework Statement


New Doc 13_1.jpg


Homework Equations


W=-∫PdV
ε=W/Q
PV=nRT
COP=Q/W

The Attempt at a Solution


Using the first equation for work, I got W=-nrT*ln(3V1/V1) but I don't think that is right. Is this the wrong formula to use for this problem? My answer should be in terms of P1 and V1.
 
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That is not the correct integration of PdV for the process shown in the figure.
 
Chestermiller said:
That is not the correct integration of PdV for the process shown in the figure.
What equation can I use to find the work then?
 
Marcin H said:
What equation can I use to find the work then?
You can use the integral of PdV. Just do it in a way that is consistent with what you see in the diagram.
 
Chestermiller said:
You can use the integral of PdV. Just do it in a way that is consistent with what you see in the diagram.
I just took the area of the rectangle. So W=2P1V1. I got an efficiency of 17% with that.
 

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