(adsbygoogle = window.adsbygoogle || []).push({}); Need urgent help with thermo problems...

Here are my problems:

1) A rigid tank contains 5 lb of a two-phase liquid vapor mixture of water, initially at 260 F with a quality of .6 Heat transfer to the contents of the tank occurs until the temperature is 320 F. Determine the initial mass of vapor, in lb, initially present in the tank and the final pressure, in psi.

For T=260, vf (specific volume of saturated liquid) = .01708 and vg (specific volume of saturated gas) = 11.77

I know quality is .6, so I can use the equation x=(v-vf)/(vg-vf) to find v.

v=7.07

For T=320, vf=.01765 and vg=4.919.

*Can I assume quality is the same and use the same equation as above to solve for v? How do I find initial and final pressures? How do I know the initial mass of the vapor?*

Hints please!

2) Water vapor is heated in a closed, rigid tank from saturated vapor at 160 C to a final temperature of 400 C. Determine the initial and final pressures, in bar, and the initial and final specific volumes, in m^3/kg.

*Here i'm having trouble discerning the relationships between p, v, and t. Can someone clarify for me?*

Thanks in advance,

eku_girl83

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# Need help with thermo problems

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