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Build a 5m rotor diameter

Posted: Jun 09 2019 6:25am
by jlcortex
I'm thinking of starting a serious project
In my opinion if you build a wind turbine you have to make it big, What do you think?

Rotor diameter = 5m
A 5m rotor can get more than 5000W but I would like to optimize for slow wind, about 6m/s, I am calculating 2500W or so.
I am thinking to build blades in wood and use a multiplied hub motor as generator.

It has sense?

Re: Build a 5m rotor diameter

Posted: Jun 09 2019 10:59am
by Lebowski
I would go vertical, somehow seems easier for diy...

https://en.m.wikipedia.org/wiki/Vertica ... nd_turbine

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 2:00am
by jonescg
A hub motor would probably be a good match considering the low speeds. Hope to see this progress :)

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 3:53pm
by jlcortex
Captura2.PNG
Captura2.PNG (342.82 KiB) Viewed 168 times
I like horizontal wind turbines. About hub motor, I see hub motors very simple, reliable and cheap. I am thinking about use a 500W 12V hub motor at 5X the nominal speed to get 2500W, it is very big motor, i think 2500W is not problem if it spin 5 times faster.

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 4:18pm
by billvon
jlcortex wrote:
Jun 09 2019 6:25am
A 5m rotor can get more than 5000W but I would like to optimize for slow wind, about 6m/s, I am calculating 2500W or so.
I am thinking to build blades in wood and use a multiplied hub motor as generator.
A 5m diameter rotor, in 6m/s wind, is going to get 2500 watts at 100% efficiency. At more reasonable efficiencies expect 1000 watts or so. Also 6m/s is about 14mph which is a pretty strong wind. We rarely see winds above 12mph down here.

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 11:16pm
by Hillhater
jlcortex wrote:
Jun 10 2019 3:53pm
..... I am thinking about use a 500W 12V hub motor at 5X the nominal speed to get 2500W, it is very big motor, i think 2500W is not problem if it spin 5 times faster.
Why 12 volts ? ....you will be dealing with high amperage .
48 -60 v would be more practical.
Also check the efficiency of the motor at 5X normal operating speeds.
A 3kW hub at normal design speeds would seem to be more realistic and still cheap.?

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 4:16pm
by jlcortex
Hillhater, I am meaning 12V hubmotor spinning at 5X the nominal speed so it will be 60V, rated current will be about 42A.
The hub motor is a huge electric motor, the power is low because the RPM is very low, but I think nothing prevents the engine from spinning much faster than it does on a bike.

this is my wind:
weatherspark.PNG
weatherspark.PNG (39.29 KiB) Viewed 117 times
https://weatherspark.com/y/42614/Averag ... Year-Round

this other site is a map with wind power density
https://globalwindatlas.info/

136W/m2 in my area at 50m. I am not an expert but I think the calculation should be something like that:
Average Power = Wind power density * Area * turbine efficiency * generator efficiency = 136*19,64*0,4*0,86 = 918W
My tower will not 50m so I estimate near 700w average, about 6MWh/year

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 5:00pm
by jlcortex
I just realized that the 12V hub motors are not very popular, but some items can be found:
https://www.alibaba.com/product-detail/ ... 78a5MKzt68

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 5:38pm
by billvon
jlcortex wrote:
Jun 11 2019 4:16pm
My tower will not 50m so I estimate near 700w average, about 6MWh/year
I get 200w average, assuming 8mph wind average.

Tower minimum height is going to be 12.5 meters plus the height of the tallest object within 200 meters of the turbine.

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 6:19pm
by Hillhater
jlcortex wrote:
Jun 11 2019 5:00pm
I just realized that the 12V hub motors are not very popular, ....
That was one reason i suggested using a higher power/voltage rated motor ...
Another being the efficiency/heat build up if you use a 500W motor to regen at 5x its rating

Re: Build a 5m rotor diameter

Posted: Jun 12 2019 3:19am
by Punx0r
jlcortex wrote:
Jun 11 2019 4:16pm
The hub motor is a huge electric motor, the power is low because the RPM is very low, but I think nothing prevents the engine from spinning much faster than it does on a bike.
Unfortunately most hubmotors are built to spin slowly. They have high pole counts and thick laminations which mean core losses become large when the speed goes much above the nominal.