Flashcards
Open Systems - Further
Cards in this deck (14)
- 1Difference between open and closed systems on the basis of per kg?
- 2What are compressors, how do they work? What kind of equipment do they use? Examples?Compressors are devices which use mechanical energy to raise the pressure of gases or vapours. There are many types of compressors such as reciprocating piston, radial vane, helical screw, etc.
E.g. air compressor, fridge compressor - 3What are turbines/expanders, how do they work? Example?Turbines or Expanders are devices used to convert thermal energy into mechanical work by expanding gases or vapours from a high to a low pressure.
E.g. gas turbine - 4A Steady-flow process of Compressors or turbines as Open systems (Control Volume):(qin - qout) + (win - out) = (h2 - h1)
- 5What do compressors/turbines typically undergo? What do the graphs look like?Compressors or turbines as Open systems typically undergo a Polytropic process.
- 6win or wout for compressor/turbine open systems:
- 7Work transfer (if frictionless and neglecting change of KE and PE):Be aware you don't need to remember this just be able to apply it
- 8Adiabatic compression / expansion with friction?No input of heat so (qin - qout) = 0, so either win or -wout = h2 - h1 = cp . (T2 - T1)
- 9What are nozzles and diffusers commonly used for?Nozzles and diffusers are commonly utilised in jet engines, rockets, spacecraft, and even garden hoses
- 10What does a nozzle do? What does a diffuser do? Examples?A nozzle is a device that increases the velocity of a fluid at the expense of pressure. A diffuser is a device that increases the pressure of a fluid by slowing it down.
E.g. air nozzle, water nozzle, nozzle in aircraft engines. - 11For nozzles and diffusers, what is the steady-flow process of open systems...
- 12Energy balance for compression and how to figure out the work-qout + win = h2 - h1 = cp . (T2 - T1)
- 13What if you did not have a temperature or pressure?Note that this is in the formula book
- 14Energy balance for expansion and how to figure out the workqin - wout = h2 - h1 = cp . (T2 - T1)
However if there is heat rejection then you would use -qout instead
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- 2nd year Thermodynamics (Information and Exam Qs) Flashcards on Open Systems - Further, created by Alice Kimpton on 28/02/2019.
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- Alice Kimpton
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