A 280-km-long pipeline connects two pumping stations. If 0.56m3/s are to be pumped through a 0.62-m-diameter line, the discharge
station is 250m lower in elevation than the upstream station, and the discharge pressure is to be maintained at300,000Pa,determinethepowerrequiredtopumptheoil.The oilhas akinematic viscosity of4.510"6m2/s anda density of 810kg/m3.Thepipeisconstructedofcommercialsteel.Theinlet pressure may be taken as atmospheric.
1 answer:
Answer:
Explanation:
(a) we take the free surface of the lake to point 1 and the free surfaces of the storage tank to point 2. We also take the lake surface as the reference level (z1= 0), and thus the potential energy at points 1and 2 are pe1= 0 and pe2= gz2. The flow energy at both points is zero since both 1 and 2 are open to the atmosphere (P1= P2= Paytm). Further, the kinetic energy both points is zero (ke1= ke2= 0) since the water at both locations is essentially stationary. The mass flow rate of water and its potential energy at point 2 kg/s70/s)m070.0)(kg/m1000(33===V&&rmkJ/kg196.0/sm1000kJ/kg1m)20)(m/s(9.8122222===gzpe
Then the rate of increase of the mechanical energy of water becomes kW13.7kJ/kg)6kg/s)(0.1970()0()(22inmech,outreach,fluid mech,===-=-=DpempemeemE&&&&The overall efficiency of the combined pump-motor unit is determined from its definition,67.2%or 0.672
NB:
Please check the attached file for clearer work.
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Answer:
a)120C
b)29kg
Explanation:
Hello!
To solve this exercise follow the steps below
1. we will call 1 the initial state, 2 the steam that enters and 3 the final state
2. We find the quality of the initial state, dividing the mass of steam by the total mass.
3 Find the internal energy in the three states using thermodynamic tables
note:Through laboratory tests, thermodynamic tables were developed, these allow to know all the thermodynamic properties of a substance (entropy, enthalpy, pressure, specific volume, internal energy etc ..)
through prior knowledge of two other properties such as pressure and temperature.
u1=IntEnergy(Water;x=0,6(quality);P=200kPa) =1719KJ/kg
u2=IntEnergy(Water;t=350;P=5000kPa) =2808KJ/kg
u3=IntEnergy(Water;x=1;P=200kPa) =2529KJ/kg
4. use the internal energy and pressure to find the temperature in state 3, using thermodynamic tables
T3=Temperature(Water;P=200kPa;u=u3=2529KJ/kg)=120C
5. Use the first law of thermodynamics in the system, it states that the initial energy in a system must be equal to the final
m1u1+m2u2=(m1+m2)u3
where
m1=inital mass=10kg
m2=the mass of the steam that has entered.
solve for m2
(m1)(u1-u3)=(m2)(u3)-(m2)(u2)