139k views
1 vote
Water having a density of 1000 kg/m3 and a viscosity of 1.55∗10−3Pa.s is pumped from an open tank as shown in the figure below. Pump supplies 44.33 J/kg of fluid in the pipe. Water is pumped through a line of commercial steel pipe having an inside diameter of 0.09 m. Length of the straight pipe is 25 m and pipe contains 90∘ elbows and a halfopen gate valve. Calculate volumetric flow rate of water at the exit pipe. (0.00572 m3/s)

1 Answer

1 vote

Answer:

To calculate the volumetric flow rate of water at the exit pipe, we can use the principle of conservation of mass. According to this principle, the mass flow rate of water at the inlet is equal to the mass flow rate of water at the exit.

First, we need to calculate the mass flow rate at the inlet. The mass flow rate (m_dot) is given by the equation:

m_dot = density * volumetric flow rate

The density of water is given as 1000 kg/m^3. Let's assume the volumetric flow rate at the inlet is Q. Therefore, the mass flow rate at the inlet is:

m_dot_in = 1000 * Q

Next, we need to calculate the pressure drop across the pipe. The pressure drop (ΔP) can be calculated using the Darcy-Weisbach equation:

ΔP = f * (L/D) * (ρ/2) * (V^2)

Where:

- f is the Darcy friction factor (which depends on the flow regime and pipe roughness)

- L is the length of the straight pipe (25 m in this case)

- D is the inside diameter of the pipe (0.09 m in this case)

- ρ is the density of water (1000 kg/m^3)

- V is the average velocity of water in the pipe

To calculate the average velocity (V), we need to know the cross-sectional area of the pipe (A). The area can be calculated using the equation:

A = π * (D/2)^2

Once we have the area, we can calculate the average velocity as:

V = Q / A

Now, we can substitute the values into the Darcy-Weisbach equation and solve for the pressure drop (ΔP).

Next, we need to calculate the work done by the pump (W). The work done is given by the equation:

W = m_dot_in * ΔP

Finally, we can calculate the volumetric flow rate at the exit pipe (Q_exit) using the equation:

Q_exit = W / (density * 44.33)

Substitute the known values and solve for Q_exit to find the volumetric flow rate at the exit pipe.

Please note that this is a simplified explanation and there might be additional factors or considerations depending on the specific problem and assumptions made.

User Mmd Amin
by
8.1k points