Yet another Uphill water pumping Situation :)

[congoRiver]

Hello All

I am pretty new in a project that we have started in Congo (DRC).
We want to bring water from the lake (lac in French) to the water tower we installed uphill (3000 Liters Cistern).

height water tower = 8 meters above 'ground'
distance lake to 'ground' = 150 meters
height lake to 'ground' = 60 meters
attached you will find a small visual illustration of the situation.

Ideally, we would like to work with solar power. The GPM/LPH is not really important if we can fill in the cistern in approx. 4 hours-time a day.

What pump would you recommend us to get? /Is there a good solar pump or system we can find ?

Thanks in advance for the help!

 

[LittleInch]

Well let's look at power because that usually is the key here.

You need to raise your water say 70m.
Add a generous 10m losses for the fluid flow ( what size / sort of pipe are you thinking of?)
So 80m

Flow of 3000 litres in 4 hours is quite low, 3000 l / x 4 x 3600 = 0.2L/sec / 12l/min / 0.75 m3/hr

but 80 m is quite high for such a system, so the power is still quite decent - say 300W.

That's probably what your average large Solar panel will give you. ( say 1.6m x 1m)
Solar power though needs to be treated right and use the correct volatages to get you possible to convert to AC and you can have losses if you don't get it right.

However finding a pump which does this might get more interesting.

I've had a quick look around and to get the required head you may need to up the flow rate by 3 or 4, hence need more solar panels or have three or four stages / pumps up the hill.

Try searching for borehole or water well pumps. something like this might do but has more power required.

https://www.amazon.co.uk/MosaicAL-0-75KW-Submersible-Wells-Cordon/dp/B07CLYJS3C?ref_=fsclp_pl_dp_12

Remember - More details = better answers
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[IRstuff]

One panel in the US is often specified at 250W, but that's peak power, not average. Should probably figure on using 4 panels to maintain sufficient pump power. The other option would be 2 panels plus batteries, where the batteries are driving the pump and the panels only charge the batteries

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[fel3]

You have a high head/low flow/low power situation. I'm in the USA and all my calculator programs for this type of stuff use US Customary (English) units, so I'm going to use both unit systems here to help me debug the calculations we need to do before we get to a pump. In some cases I am using a soft conversion, but the differences here are slight. If someone finds a mistake, please correct me.

Your minimum desired flow rate is 3,000 l / 240 min => 12.5 l/min (3.3 gpm). If we round up to 15 l/min (4.0 gpm), use a 50-mm pipe (2.0 in), and assume a Hazen-Williams C of 130 (probably slightly conservative), the head loss in the 150 m (492 ft) of discharge piping would be less than 0.1 m (0.3 ft). This is small enough to ignore. However, the flow velocity (0.12 m/s or 0.4 fps) is probably far too low for this situation since you are pumping raw water. I just don't know how "raw" your raw water is.

If we use a 25-mm pipe, the head loss would be 2.5 m (8.2 ft) and the flow velocity would be 0.5 m/s (1.6 fps). You might want an even smaller pipe, so as to increase the velocity, but I don't know what sizes you have available. In any event, the penalty for using a smaller pipe would be higher head losses. However, for this discussion, I will keep the pipe at 25 mm. On this basis, we can estimate a total dynamic head of about 60 m + 8 m + 2.5 m = 70.5 m (231 ft), plus a little for minor losses. Let's say the TDH with everything is 71 m (233 ft).

Assuming a pump hydraulic efficiency of 70%, the power requirement for a pump flowing at 15 l/min and generating 71 m of head is 0.25 kW (0.34 hp). IIRC, the smallest pump I have used was 0.5 hp or maybe 1 hp for a sump in a truck loading dock. I don't know what efficiency to assume on the electrical side (IIRC, most of my systems have been in the 92%-94% electrical efficiency range). Regardless, I would think that if a solar power system that generates at least 0.3 kW would be OK. I would probably target 0.4 kW or 0.5 kW just to be sure. However, since I am not an electrical engineer and I have never used solar power for this type of installation, take this part of the discussion with a grain of salt.

My first thought is some sort of submersible pump. I have seen (but not designed) two installations for pulling raw water directly out of a lake. Others on this forum will certainly have more experience with this type of project. One installation used a submersible sewage pump hung beneath a raft (see

https://www.xylem.com/en-us/brands/flygt/flygt-products/c-3085

for an example of a pump that I have used for sewer service). The other installation used a multi-stage submersible pump mounted to a raft. I didn't actually see this pump, but it was described to me as being similar to a vertical turbine booster pump or a vertical turbine well pump with a short shaft. I suspect it was something like this:

https://www.pumpproducts.com/goulds...IsuSlv9LE5QIV4SCtBh1f_w9ZEAYYASABEgJc1PD_BwE.

The problem with the sewage-type submersible pumps that I am familiar with (which have only one impeller) is that I don't think any exist that can pump as little as 15 l/min at a head as high as 71 m. You are more likely to find a pump that do something like 150 l/min at 10.5 m TDH.

On the other hand, there should be multistage submersible pumps that can meet these service conditions, although I didn't find a perfect match in my limited search.

If you don't go the submersible route, then the project gets more complicated, so I won't go there now.

I did find some solar powered pumps, but none that would meet these service conditions. So, I suspect you are going to have to get the pump and solar panel separately and integrate the two. Again, someone with more experience in what you are trying to do may have the perfect solution that I wasn't able to come up with. But, I hope this is still useful to you.

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[LittleInch]

congo,

This should give you some numbers to work with.

somewhere like the DRC, you really just need to find out what you can get locally and adapt it / work with it to achieve your aims.

One thing you could try is using an air operated pump (AODD)

Normally these are limited to about 70m, but there are some higher pressure ones, but you then need to find a solar power air compressor good for at least 8 bar discharge and a decent air vessel....

e.g.

https://www.graco.com/gb/en/products/process/husky-1050hp.html

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

The most efficient solar water pumps for wells are “positive displacement” pumps. However, what is economical for you will depend on the specifics of the installation. Review the following:

Pumps

 

[congoRiver]

Hello guys

With all the combined info, I am now sure we can think of a system that will work over there.

I guess our main concern is the head height and the distance. So this will require a powerful power enough source to support the type of pump required. We are now on a good track.

thanks a lot to each of the contributors!

 

[Artisi]

Check

http://www.lorentz.de.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

Interesting pumps and systems but look rather big for this duty unfortunately, even the smallest one.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[itsmoked]

How'd I miss this fun thread?

congo; How's the project going?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[3DDave]

Dammit - missed this was for a lake.
This might be an aid -

https://lurkertech.com/water/pump/tailer/

It should lower the electrical requirements.