Calculating Energy Loss Due to Friction in Polyethene Pipe
How can we calculate the energy loss due to friction in a polyethene pipe?
Calculate the energy loss due to friction using:
- Hazen-William equation
- Scooby equation
- Darcy-Weisbach equation
Calculation of Energy Loss Due to Friction
When water flows through a pipe, it encounters friction which causes the energy of water to dissipate. The energy loss due to friction is an important factor that must be taken into account in any engineering calculations. The energy loss due to friction can be calculated using various equations such as the Hazen-William equation, Scooby equation, and Darcy-Weisbach equation.
Given data: Length of pipe (L) = 250 m, Diameter of pipe (d) = 120 mm = 0.12 m, Water flow rate (Q) = 20 litres/sec = 0.02 m3/sec.
Hazen-William Equation
The Hazen-William equation is given by: ƒ = 0.2083 × (C)1.85 × (d)-4.87 × (L)-1.85, where ƒ is the friction factor, C is the Hazen-Williams coefficient, d is the diameter of the pipe, and L is the length of the pipe. The Hazen-Williams coefficient for polyethylene pipes is 150.
By substituting the given values, we calculate the friction factor as ƒ = 0.0191.
The energy loss due to friction can then be calculated as ΔE = 4097.5 Joules using the given formula.
Scooby Equation
The Scooby equation is an empirical equation used to calculate the friction factor. It is given by: 1/√ƒ = 2.0 × log10(3.7 × d/ε) + 1.74/Re^0.9, where ε is the roughness of the pipe and Re is the Reynolds number. The roughness of polyethylene pipes is 0.0001 mm.
The Reynolds number can be calculated using Re = (ρ × d × v)/μ, where μ is the dynamic viscosity of water (0.001 N-s/m2).
Substituting the values and calculating, we can determine the energy loss due to friction.