- #1

ConnorM

- 79

- 1

## Homework Statement

The mass flow rate through a steam turbine operating under steady conditions is 100 kg/s. Steam enters the turbine at 12 MPa and 400

^{o}C. A mixture of vapour and liquid water exits the turbine at 10 kPa. At the exit state 93% of the mass of the water is in vapour form. The turbine loses heat to the surroundings at the rate

of 3 MW. Kinetic and potential energy effects can be ignored.

*a)*Draw a schematic of the system and clearly indicate the system boundary

using a dashed line. Indicate and label the mass flow inlets and outlets. Using

arrows, illustrate the energy transfers between the system and surroundings

by heat transfer and by work.

*b)*Write a 1st law energy balance for the system that agrees with your schematic. Cancel all unnecessary terms, providing justification for why these terms can be cancelled.

*c)*Draw the process on a T-s diagram, clearly indicating the state points and the isobars corresponding to the state points.

*d)*Calculate the power generated by the turbine in MW.

*e)*Calculate the change in specific entropy from inlet to exit in kJ/KgK.

## Homework Equations

**Question 2**s

_{1}=s

_{f}+ x[ s

_{g}- s

_{f}]

Also since there is one inlet and one exit,

m=m

_{1}=m

_{2}

I am pretty sure this equation will be useful as well,

0= Q - W + m[ (h

_{1}- h

_{2}) + ((v

_{1}

^{2}- v

_{2}

^{2})/2) + g(z

_{1}+ z

_{2}) ]

but since kinetic and potential energy is negligible I think I can cancel out ((v

_{1}

^{2}- v

_{2}

^{2})/2) + g(z

_{1}+ z

_{2})]

That would leave me with,

0= Q - W + m[ (h

_{1}- h

_{2}) ]

## The Attempt at a Solution

For the second question I'm not really sure what to do, I think that what I would have to do is find s

_{g}from using 12 MPa, 400

_{o}C and looking at the steam table for water.

I'm not sure what I could do next because I would have 2 unknowns for the equation,

s

_{1}=s

_{f}+ x[ s

_{g}- s

_{f}]

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