Answer:
a) , b)
, c)
Explanation:
a) The tank can be modelled by the Principle of Mass Conservation:
The mass flow rate exiting the tank is:
b) An expression for the specific enthalpy at outlet is derived from the First Law of Thermodynamics:
Properties of water are obtained from tables:
The specific enthalpy at outlet is:
c) After a quick interpolation from data availables on water tables, the final temperature is:
Answer:
Mechanical Efficiency = 83.51%
Explanation:
Given Data:
Pressure difference = ΔP=1.2 Psi
Flow rate =
Power of Pump = 3 hp
Required:
Mechanical Efficiency
Solution:
We will first bring the change the units of given data into SI units.
Now we will find the change in energy.
Since it is mentioned in the statement that change in elevation (potential energy) and change in velocity (Kinetic Energy) are negligible.
Thus change in energy is
As we know that Mass = Volume x density
substituting the value
Energy = Volume * density x ΔP / density
Change in energy = Volumetric flow x ΔP
Change in energy = 0.226 x 8.274 = 1.869 KW
Now mechanical efficiency = change in energy / work done by shaft
Efficiency = 1.869 / 2.238
Efficiency = 0.8351 = 83.51%
