Rankine cycle thermodynamics problems?

[haley5p]

Rankine cycle exam questions

Q1 A steam plant is designed on the basis of an idealised Rankine cycle where the plant raises steam at 3MPa and 350 °C. The steam is then expanded through a turbine and fed to a condenser that operates at a pressure of 12 kPa.

i) Draw a flow diagram and sketch a temperature–entropy diagram for the process. You should ensure that you label the four key stages of the process on each diagram.

ii) Determine the thermal efficiency of the process

iii) In reality the pump and turbine are found to operate with efficiencies of 60% and 70% respectively. Given this determine the thermal efficiency of the actual plant

iv) State how the thermal efficiency of the plant could be increased (use diagrams to support your answer).

Q2 real rankine power cycle question

 

A steam plant is operated on a real cycle shown below. The pump operates on a efficiency of 75% and the turbine operates on an efficiency of 70% determine the thermal efficiency of the cycle. And the plant power output for a mass flow of 10kg/s

 

 

 

 

Q2a

The real steam plant is redesigned and its is discovered that the plant can be run at 20MPa by adding a second pump (efficiency 90%) Calculate the change in efficiency of the modified plant The new heat input to the system and the heat lost in the condenser comment on the quality of the steam in the turbine

 

 

 

 

[CaptainPanic]

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Moderator Note

haley5p,

 

Please note that this is obviously homework. You will not get any answers, unless you show what you have so far done to solve these problems. Posting only the questions is not sufficient. You are obviously doing some engineering course, not a management course, so asking other people to do your work is not going to teach you the necessary skills to pass the class.

 

Everybody,

Please do not answer any questions until our OP has shown any efforts into solving these problems.