Thermodynamics - Energy analysis of piston-cylinder device

AI Thread Summary
The discussion revolves around a thermodynamics homework problem involving a piston-cylinder device, specifically focusing on energy analysis and boundary work calculations. The user has successfully solved part (a) and identified the saturation temperature for part (c) but is struggling with part (b), needing clarification on the given properties and the appropriate formulas to use. They confirm the volume relationship and seek guidance on how to approach boundary work for real gases, noting their professor's comment about numerical integration for the work calculation. The conversation highlights the challenges of applying theoretical concepts to practical problems in thermodynamics. Understanding the numerical approach for real gases is crucial for solving the problem accurately.
eh87
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Hello :)

I'm having trouble working on this homework question (please see attachment). The answers are supposed to be
a) 22.61 KJ
b) 36.79 KJ
c) 151.8*C

I solved (a) and I noticed that the answer to (c) is that saturation temperature at 500kPa, but I just cannot get (b)! In fact, I'm not really sure I even know what's given for part (b). Obviously P=500kPa, but what else is known? Would Vb = 0.6(Va) = 0.0551898 m^3 ? It seems like I need another intensive property (other than P) to identify the state as a start.

help :confused:
 

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I just read the sticky about homework. Sorry.
 
So I worked on it some more, just trying to understand the darn thing.. and yes, V_{b} = 0.0551898 m^3. Now which formula to use for boundary work?

For constant temp and an ideal gas, I know the formula:
W_{b} = \intmRT/VdV = mRT*ln(V_{2}/V_{1})

But prof said that for real gases undergoing an isothermal process, the integral in the boundary work equation "would be done numerically." What does that mean??
 
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