Flow devices thermodynamics problems?

[haley5p]

thermodynamics tutorial on flow devices

Q1)

 

Air at 150Kpa and 300K is compressed to 1.5 MPa At 400 K

The air flows at 0.5 Kg/s and heat is lost from the compressor at a rate of 16KJ/kg during the process

Determine the power input to the compressor

Past exam questions

 

Q2)

 

Water at 15 ˚C is fed to the top of a spray column by a centrifugal pump from a bulk storage tank at a rate of 50 kg/min. The storage tank is 15 m in diameter 3 m deep and the level within the tank is maintained at 2 m by a float valve connected to the mains water supply.

The pump draws water from the bottom of the bulk storage tank at ground level and discharges it though a nozzle mounted in the roof of a spray tower 25m high. The pipes connecting the tank, pump and nozzle are all 5cm bore. The nozzle has an outlet diameter of 1 cm and is 3 cm long. The spray tower is vented to atmosphere and is drained at its base.

 

a) Draw a diagram of this process

b)The outlet velocity of the nozzles.

c) The pressure at the inlet of the nozzle

d) Power input by the pump assuming 100% efficiency.

e) The pump actually operates at 80 % efficiency, recalculate the power input to the pump.

 

Q3)

A fire engine pumps water a a rate off 1000 kg/min from a river 3m below the fire engine to put out a fire on the 5^th floor of a building 15m above the fire engine. The water is pumped through a hose 100 mm in diameter to a nozzle outlet diameter 15mm and 60 cm long.( assume outlet at 298 K and 1 atm pressure)

 

Calculate( Stating all assumptions):

 

a)The outlet velocity of the nozzles

b)The pressure at the inlet of the nozzle

c)Power input by the pump assuming 100% efficiency

d)The pump actually operates at at 80 % efficiency recalculate the power input to the pump

e)What could have happened to the 20 % of energy lost during the pumping stages. Explain your comments and state wheather this could have affected your previous calculations

[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.