METEO 300 Lecture Notes - Lecture 28: Isentropic Process, Superheating

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4 Jan 2018

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Me 300 - lecture 28 - isentropic efficiency. Efficiency of a process: the amount of work that can be converted to heat. *this is optimized when the process is isentropic (adiabatic and reversible), where no work is loss due to irreversibilities such as friction. Isentropic efficiency for steady flow devices: found by comparing the actual work produced (by turbines for example) or needed (by compressors or pumps) to the optimal power (isentropic power). A superheated steam (t=800 k, p = 2 mpa, flow rate = 100 kg/s) is used to drive a turbine. The steam leaves the turbine at a temperature of 660 k and a pressure of 0. 3. Using saturation tables and 1 = 800 k and 1 = 2 mpa, you should find that. Using saturation tables and 2 = 660 k and 2 = 0. 3 mpa, you should find that. = 100 [3527. 6 3248. 1] = 27. 95 mw. Now, we want to find the isentropic power out:

Related Questions

An adiabatic air compressor is to be powered by a direct-coupled adiabatic steam turbine that is also driving a generator. Steam enters the turbine at 12.5 MPa and 500°C at a rate of 25 kg/s and exits at 10 kPa and quality of 0.92. Air enters the compressor at 98 kPa and 295 K at a rate of 10 kg/s and exits at 1 MPa and 620 K. Determine the net power delivered to the generator by the turbine

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Propane question

A quantity of propane is contained in a piston-cylinder assembly. This working fluid undergoes a process starting from an initial state of 2.0 MPa and 60oC. At the end of the process the pressure of the propane is 1.0 MPa and the specific entropy is 0.089 kJ/kgK higher than at the start of the process.

Determine the temperature of the propane at the end of the process.

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

Do the following: (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

METEO 300 Lecture Notes - Lecture 28: Isentropic Process, Superheating

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