Thermodynamics - Dryness fraction Equations

AI Thread Summary
The discussion revolves around calculating the dryness fraction and enthalpy in thermodynamics. A specific volume of 0.2 m^3/kg leads to a dryness fraction (x) of 0.4311. The user initially questions whether to use h = hf + (x.hfg) or h = x.hg + (1-x).hf for calculating h1. After further clarification, it is revealed that the user mistakenly entered values into the calculator, leading to confusion over the enthalpy results. The inquiry is ultimately resolved, and the user retracts the question.
maserati1969
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Homework Statement
A cylinder fitted with a piston has a volume of 0.1 m3 and contains 0.5 kg of steam at 0.4 MPa. Heat is transferred to the steam until the temperature is 300 °C, while the pressure remains constant. Determine the heat transfer and work done for this process. Neglect the change in kinetic and potential energies.
Relevant Equations
Q-W = Delta U
Q = m(h2 - h1)
h = hf + (x.hfg)
I found the specific volume to be 0.2 m^3/kg (0.1 / 0.5), this gives me a dryness fraction (x) of 0.4311
Then I can use Q = m(h2 - h1)
h2 is just enthalpy for superheated steam at 400kPa and 300 Celsius = 3066.8 kJ/kg
but for h1 do I now use:
h = hf + (x.hfg)
or do I use
h = x.hg + (1-x).hf
I get a different enthalpy value for each and not sure which to use?

Thanks in advance for any help
 
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Sorry, it's the same equation, and I don't get a different answer, I entered it into the calculator incorrectly. Sorry, ignore this question !!
 
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