- #1

rock.freak667

Homework Helper

- 6,223

- 31

## Homework Statement

Wet steam at 0.5Mpa, quality 0.84 is to be heated to dry saturated steam. Determine the heat required if it is heated at constant volume and at constant pressure.

## Homework Equations

h=h

_{f}+xh

_{fg}

u=u

_{f}+xu

_{fg}

s=s

_{f}+xs

_{fg}

v=v

_{f}+xv

_{fg}

## The Attempt at a Solution

WET STEAM

Sat. pressure 500.0000 kPa

Sat. temperature 151.8438 C

Quality 0.8400

Moisture 0.1600

Enthalpy 2410.3480 kJ/kg

h

_{f}640.1158 kJ/kg

h

_{fg}2107.4194 kJ/kg

h

_{g}2747.5351 kJ/kg

Internal energy 2252.8966 kJ/kg

u

_{f}639.5693 kJ/kg

u

_{fg }1920.6277 kJ/kg

u

_{g }2560.1970 kJ/kg

Entropy 6.0258 kJ/kg/C

s

_{f}1.8604 kJ/kg/C

s

_{fg}4.9588 kJ/kg/C

s

_{g}6.8192 kJ/kg/C

Specific volume 0.3149 m3/kg

v

_{f}0.0011 m

^{3}/kg

v

_{fg}0.3736 m

^{3}/kg

v

_{g}0.3747 m

^{3}/kg

this is what I found so far from the tables

At constant volume: (W=0)

1st law: Q-W=U

therefore Q=U=m(u

_{2}-u

_{1})

I can get the specific entropies, internal energies, volumes,enthalpies from the tables.

But how do I get the mass?