Off Grid Micro Hydro Power Generator Part 2 - Planning 2.0

After deciding to look into a micro hydro power generator we are still experimenting with water flow. Knowing that we need around 10litres a second, i sourced some 45mm irrigation pipe x 2 to make 90mm. The test results where hopeless, way too much friction within the the pipes. We are going to go back to the original idea and run a single 90mm pipe. Experiments - that's what it's all about, will it work?

[@andrewallason4530]

Yup. Two 45mm pipes is NOT the same as one at 90mm. More like 1/3 of the flow (with friction losses). You can get Blueline pipe 100m rolls at 110mm external diameter for about $1200 for the thin wall stuff (used in mining and some new subdivisions). It’s rated to about 85psi (well above what you are going to be getting).
Cheers from southern Tassie.

[@MarkRose1337]

Ah, I see you realised the PSI to meters of head connection in this video.

[@Mr.Engineer.]

Remember that doubling of diameter of a pipe 4x the cross sectional area.
So 2x 50mm pipes will flow half of 1x 100mm and even less as the 2x 50mm pipes will have more friction.

[@FatCowFarmTatong]

G'day LasseBB - your spot on. The friction ravelling through the 2 x 45mm was huge. We had to change the system over to a single 90mm to achieve our goal of 7 litres a second or greater. Thanks for watching, cheers!

[@Theodor857]

​@FatCowFarmTatong 2 x 45 mm will not equal 1 x 90 mm pipe even if you disregard pressure. Remember the surface area of a circle (amount of water it will let through) is πr², so if your radius (half diameter) halves the area is way less than half. As your diameter increases your volume increases exponentially, it is not linear. A 90 mm pipe will give you an area of 6361 mm² whereas a 2 x 45 mm pipe gives you a combined area of 3180 mm². In other words, you will need 4 x 45 mm pipes to get an equivalent of 90 mm pipe volume, and of course, the resistance factor comes in

[@chrisrhodes5464]

You may want to go with a 120 mm pipe it will give even more volume with not much deference in cost and I always say bigger is better it may also give you the extra wattage you may need for the electrical resistance you have yet to consider

[@Natreely747]

Easier to put your measurements into Ecoinnovation's Powerspout Advanced Calculator; use the TRG one for that sort of height.

[@kletusbobby7029]

The flow through 2x 45mm diameter is less than a single 90mm.

[@ktmrider7592]

The bigger the pipe the more power available. My creek will give me easily 500 gpm so I wanted the most power possible so I went with 8” pipe that was capable of giving me the most power. I will be running two turgo 1300 w turbines allowing me to make 3kw continuous.
You also have to account for friction loss of your pipe. There are also charts out on the web that will tell you .
If you can get 10 more meters down towards the house why not go for that? The more psi the better.

[@FatCowFarmTatong]

Hey KTM, 500gpm - wow! that's full on. Do you have any thoughts on how you are going to use or dump the excess power? That's 72 KWH a day, are you connected to the grid? Selling that power back into the grid you could retire. Fantastic system. Well done! cheers

[@TheBadweasel1975]

@@FatCowFarmTatong something off the beaten path but with that water flow if you cant get enough pressure concider a water wheel (piped into a short shute before it flows over wheel) or a vortex low head turbine that depends more on volume or even both use the waste water from a pelton tubine (high pressure) into a shute over a waterwheel
look up marty t as well he has a couple of vids on how to divert exess power to your hot water tank (or spa) on the cheap

[@ktmrider7592]

@@FatCowFarmTatong I am planning on using the power to also heat my house. That’s why I went so big. That kind of flow is only available in the winter months. I will probably just shunt the excess power to a electric garage heater.