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Home > Forums > Mechanical Engineers > Activities > Pipelines, Piping and Fluid Mechanics engineering Forum

Submersible pump heat gain

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DeltaH (Industrial) (OP)

30 Jan 09 11:08

Looking for a rule of thumb to estimate heat gained from a submersible pump in a temperature sensitive aquatic system. Have a 17.6 KW pump sized @ 75% efficiency, what precentage of wasted energy can I assume or calculate will be transmitted to the water system as heat?

DeltaHydro

hydtools (Mechanical)

30 Jan 09 11:36

25% ? The inefficiency.

Ted

DeltaH (Industrial) (OP)

30 Jan 09 11:52

That is what I assumed, the obvious. I guess any sound power and vibration energies would be transmitted into the submerged water environment too oppossed to a dry mounted pump installation. So I'll assmue all wasted energy ~ 25% THANKS

DeltaHydro

hydtools (Mechanical)

30 Jan 09 14:04

That would be worst case. Some heat will be removed by product that leaves the system.

Ted

DeltaH (Industrial) (OP)

30 Jan 09 14:27

THANKS hydrotools

All water is recirculated within the system, and will be subject to ambient conductive and convection surface area losses which I need to calculate.

DeltaHydro

badservo (Industrial)

30 Jan 09 21:23

hydtools answered your question correctly, but you only asked about the wasted energy, where is the other 75% going?

BigInch (Petroleum)

31 Jan 09 3:31

Maybe .. increasing the water pressure.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

Bribyk (Mechanical)

31 Jan 09 12:19

I think badservo's hinting that, if it's a recirculating system, isn't 100% of the input energy going into the water?

hydtools (Mechanical)

31 Jan 09 13:01

If the pump is recirculating, all the energy goes into the system and you are not dealing with only the inefficiency.

Ted

unclesyd (Materials)

31 Jan 09 13:04

Looking at BigInch's tag line what % of the input is the motor given up as heat, etc.?

IRstuff (Aerospace)

31 Jan 09 14:18

Sure, the VitaMix can just about boil water just from the churning of its blades, so ALL of the power consumption would go into the water, either kinetic energy or as heat.

TTFN

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BigInch (Petroleum)

31 Jan 09 21:19

Assuming a closed hydraulic system, he's only losing energy by evaporation from the surface of the aquarium and conduction through the floor and walls, which is probably a considerable amount, but he needs to calculate the possible minimum and maximum stabilization temperatures.

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