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Steam Turbine Review

Steam Turbine Review. Steam turbine and its representation on a T-s diagram (Thermodynamics 4 th ed., Cengel and Boles, Figure 6-50). Basic Equations. Engine Basics. Dynamometer: Measures RPM and torque of steam turbine shaft and applies load.

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Steam Turbine Review

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  1. Slides forME 115 Steam Turbine Review Steam turbine and its representation on a T-s diagram (Thermodynamics 4th ed., Cengel and Boles, Figure 6-50)

  2. Slides forME 115 Basic Equations

  3. Slides forME 115 Engine Basics • Dynamometer: Measures RPM and torque of steam turbine shaft and applies load. • Torque: a force acting through a radius; common units ft lbf • Brake (shaft) horsepower: derives its name from the fact that the power output of an engine can be measured using a dynamometer to apply a torque to resist the turning of a shaft

  4. RPM1 Efficiency RPM2 Rated power Slides forME 115 Engine Basics • Efficiency changes with bhp. • The maximum efficiency will occur at different bhp’s for different RPM’s.

  5. Slides forME 115 Temperature and Pressure Measurements • Temperature • Thermocouples: voltage changes with temperature • Thermistors and RTDs: resistance change with temperature • Thermometers • Pressure • Manometers • Transducers

  6. Slides forME 115 Temperature Sensors Industrial thermocouples Various thermocouple bead styles Thermocouple probes Thermometers Thermistors

  7. Slides forME 115 Thermocouple Basics • Seebeck effect • If two wires of dissimilar metals are joined at both ends and one end is heated, current will flow. • If the circuit is broken, there will be an open circuit voltage across the wires. • Voltage is a function of temperature and metal types. • For small DT’s, the relationship with temperature is linear • For larger DT’s, non-linearities may occur.

  8. Slides forME 115 Thermocouple Basics • If you attach the thermocouple directly to a voltmeter, you will have problems. • You have just created another junction! Your displayed voltage will be proportional to the difference between J1 and J2 (and hence T1 and T2). Note that this is “Type T” thermocouple. www.omega.com

  9. Slides forME 115 External Reference Junction • A solution is to put J2 in an ice-bath; then you know T2, and your output voltage will be proportional to T1-T2. • Handheld thermocouple readers and computer data acquisition systems use something called an isothermal block instead to perform this task.

  10. Slides forME 115 Comparison of Pressure Instruments

  11. P1 P2 H Manometer fluid Slides forME 115 Manometer Basics • Pressure varies with depth for constant density fluid

  12. Slides forME 115 Manometers/MicromanometersExamples (b) Micromanometer (c) Inclined Source: www.dwyer-inst.com (a) U-tube

  13. Slides forME 115 Pressure Transducer Basics Diaphram strain • Strain on a diaphram is linearly proportional to pressure difference for the following conditions: • A strain gage changes in resistance with strain. • This resistance change can be indicated by the voltage output of a bridge circuit. Strain gage Bridge circuit

  14. Slides forME 115 Pressure Transducer Examples (c) General purpose • Low pressure • (Validyne DP103) (d) Miniature Source: www.omega.com (b) High performance

  15. Slides forME 115 Dial Gauges • A deformable pressure sensing element is attached to a pointer which rotates against a graduated dial--like these children’s party blowouts: • Sources of error include: human error, hysteresis Examples from: www.omega.com

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