Energy Losses , Classification

Energy losses :

-  when a fluid is flowing through a pipe , the fluid experiences some resistance . This cause loss of some energy of the fluid  . 

This Loss of the Energy is classified as  :

- Friction losses

- Loss in fitting 

- Enlargement loss

- Contraction Loss

1. Friction Loss :

- Pressure Drop due to friction in a fluid .

- Fanning Equation :

Pf  = 2*f*u*u*L*(rho) / D

f =  friction factor '

u = Velocity

(rho) = density

D = diameter of pipe 

L =  Length of pipe 

Value 'f ' depends on nature of flow of fluid and roughness of the inner surface of the pipe .

For Viscous flow pressure drop can be calculated by Hagen- Poiseuille equation .

P = 32Lu(mue) / D*D  

2. Losses in Fitting :

- when fittings are introduced into a straight pipe they cause disturbance in the flow which results in addition loss of energy .

3. Enlargement Loss :

1.  gradual Enlargement ( no loss of energy )

2. sudden Enlargement ( Loss of energy )

He = ( u1 - u2 )^2 / 2g

4. Contraction Losses :

- Cross section of the pipe is reduced suddenly , the fluid is disturbed 

u2 >> u1

He = Ku2^2 / 2g

K = constant depends upon relative area of two section .