Is anyone else currently taking thermo I and wants to share thoughts on the HW, let me know. Im in need of assistance.

[Edited on July 10, 2006 at 10:10 PM. Reason : 3]

7/10/2006 10:10:41 PM

everyone has taken thermo

post the question(s)

7/10/2006 10:13:19 PM

are you in Roberts's class? I am sitting here completely lost. I definitely thought danby was a better teacher

is there a solutions manual for this book?

[Edited on July 10, 2006 at 10:18 PM. Reason : slns man]

7/10/2006 10:18:18 PM

4-40, 5th edition

A piston cylinder device initally contains .8 m^3 of saturated water vapor at 250kPa. At this state the piston is resting on a set of stops and the mass of the piston is such that a pressure of 300kPa is required to move it. Heat is now slowly transferred to the steam until the volume doubles. Show the process on a P-v diagram with respect to saturation lines and determin the final temperature, the work don during this process and the total heat transfer.

7/10/2006 10:18:53 PM

if you post the question many people on here could help you with the problem

[Edited on July 10, 2006 at 10:19 PM. Reason : just did]

7/10/2006 10:19:14 PM

^^^ im in Danby's class

7/10/2006 10:21:50 PM

no thoughts?

7/10/2006 11:48:10 PM

It's a constant volume process until the pressure reaches 300kPa, then it is a constant pressure process until the volume is doubled. It might help to think of it as two separate problems, then figure up the totals at the end.

7/10/2006 11:53:50 PM

Ok that definitely helped my visualizing the problem.

So im trying to figure out how to find the temperature increase while knowing that the volume increases .8m^3 and the pressure stays at 300kPa....what am i missing?

7/11/2006 12:03:55 AM

You can calculate the mass of the water from the first step because you know the initial volume of water vapor (.8m^3) and the specific volume (vg @ 250 kPa). Then you can use the mass to calculate the specific volume at the end when the volume of the cylinder has doubled. This means you know the final pressure and specific volume and because only two intensive properties are required to completely specify the state, you can find the final Temperature from the tables. You may have to interpolate to find the answer though. Hope that helps.

7/11/2006 12:14:15 AM

thanks so much.

7/11/2006 12:53:06 AM