Effect of head loss in pump power calculation
Effect of head loss in pump power calculation
(OP)
Hello,
The output pump power(Watt) based on chaning the head (h) is:
Power=ro*g*h*Q
but how to take into account the effect of headloss(m) in the equation.
The output pump power(Watt) based on chaning the head (h) is:
Power=ro*g*h*Q
but how to take into account the effect of headloss(m) in the equation.





RE: Effect of head loss in pump power calculation
RE: Effect of head loss in pump power calculation
Pump curves without system curves are useless. Once you've drawn your system curve, its intersection with the pump curve will give you the operating point of the pump (Q,h). h is the head your pump has to produce to overcome the head loss of the system at the operating flow rate.
RE: Effect of head loss in pump power calculation
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.com
RE: Effect of head loss in pump power calculation
Ht = Hd – Hs (considering suction head)
With
Ht = Total differential head
Hd = Total discharge head
Hs = Total suction head
And
Hd = static discharge head + velocity discharge head + friction head in the discharge line
RE: Effect of head loss in pump power calculation
Let me raise again my question in this way:
For a pump-turbine in pump mode with maximum power input of 270MW, and 50 m3/s it is required to pump water to level i.e. 420m, with total head loss about, say 10m,
How to calculate efficiency of pump just base on above assumption?
I 've calculated in this way: I subtract head loss of total required head!
P out= ro*g*h*Q=1000*9.81*(420-10)*50=201.105 MW
so
e=P out/Pin= (201.1/270)*100= 74.48%
Please correct me.
RE: Effect of head loss in pump power calculation
The reason for this is because the head loss really creates more head for your pump to have to overcome (kind of ironic).
RE: Effect of head loss in pump power calculation
input power is that provided by the motor at the pump shaft.
Output power required can be calculated by your first power formula, if H is the differential head.
Nothing to do with inlet and outlet pressure as you've shown it. That could only be related to the equivalent differential head. As you can see, you've missed accounting for flowrate and density and the pump characteristics important for determining its ability to convert input energy into useful output energy into the fluid.
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.com
RE: Effect of head loss in pump power calculation
Dear "Biginch" the equation which I've wrote is based on Power input/ouput not pressure (Pin and Pout)
As tigerbEIT mentioned I think I need to add the head loss to the total head required to remedy the head friction in calculating the delived output power? What is your Idea Biginch?
RE: Effect of head loss in pump power calculation
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.com
RE: Effect of head loss in pump power calculation
Please be more specific next time as there are other efficiencies that involove the pump (i.e. volumetric, mechanical, hydraulic, etc.).
RE: Effect of head loss in pump power calculation
Is it required to have more information for determining efficiency of pump-turbine in pump mode?
Thank you again
RE: Effect of head loss in pump power calculation
Assuming you know the hydraulic power,
HP = ro * g * h * Q,
where h is the "differential head" of the pump,
NOT "head loss"
Differential head can be found from,
(pump outlet pressure - inlet pressure) / fluid_density
Then PUMP Eff = HP / Shaft_input_Power
Now have that read at Quarks' link.
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.com
RE: Effect of head loss in pump power calculation