Hand Crank Dynamo - http://tiny.cc/2sqo5
I have 4 whirlybirds and each will have a Hand Crank Dynamo from jaycar running.
the wiring is auto wire & battery to charge up.
Does anyone know where to obtain what i need next?
thanks
steven
Hand Crank Dynamo - http://tiny.cc/2sqo5
I have 4 whirlybirds and each will have a Hand Crank Dynamo from jaycar running.
the wiring is auto wire & battery to charge up.
Does anyone know where to obtain what i need next?
thanks
steven
You need to know a fair bit more. It is unlikely a whirlybird will produce enough 'power' to turn the dynamo and charge a battery. A small solar module around 10W may be a better choice.
What size battery are you intending to connect?
I already have the 4 Wirlybirds installed.
I'd like to know is where can i get a coil of auto wire & how do i wire the 3 dynamos together and finally to the battery, with clips? so where do i get these things along with a suitable battery?
The coil would need to be 20-30 meters, and id don't know about the battery, are charged down batteries, enough to fit my requirements, at the second hand shop ?
The Dick Smith Dynamo Small 6.0-9.0VDC 220mA
Whilst the 3 Jaycar ones are larger than that.
thanks
steven
Hate to say it but this won't work, the reason whirlybirds turn is because they have virtually no load on them. As soon as you place a load like a generator on them they will stall. This type of wind turbine is very low efficiency, they are not designed to produce much energy, just move a small amount of air. Further, you are using low grade plastic gearboxes which have high transmission losses, making thing more inefficient still. If you do get any energy, it will be only in high winds, and it won't me much, less than a watt.
For the money you are spending you could have bought a 20 watt solar panel which will produce over an amp in good sun, a much better proposition than a whirly bird generator...
Steven,
Had the same idea myself, and did some searching. Check this out:
http://www.learnonline.com/pdf/Whirlybird%20Wind%20Turbine%20User%20Manual.pdf
let us know if you get it working.
That's simply a learning tool, it can't produce any usable energy, trying to charge batteries etc from a whirlybird is simply a waste of time...
Looks like a working example of what Steven was after.
Also found a number of kits which you can buy, here's one example:
http://www.picoturbine.com/search.php?search_query=whirlybird&x=0&y=0
At 30MPH that picoturbine gives you 1.2W. The mean wind speed at a weather station near me is 15km/h at 3pm, which would give you 3% of 1.2W = 0.036W. At that rate a 3.6V 1.6AH battery (mobile phone) stores 5.7WH, would take 5.7 / 0.36 = 160 hours to charge. Most modern phones need to be recharged every 24 - 72 hours.
As Lance said, trying to charge batteries from a whirlybird is a waste of time.
Back to the topic of this thread, keeping the house cool is a better objective than keeping the roof cool. You don't spend much time on the roof or just below it.
15km/h = 9.3mph , so thats 31% of 1.2W which is 0.37W. You dropped a zero somewhere....
I believe these whirlybirds would spin (slightly) faster due to convection - hot air rising out of the roof.
Also they can do something at night c.f solar.
Is it still a waste of time? don't mean to be picky but I really have no idea!
Power in wind goes up with the cube of velocity. So (15 / 48) ^ 3 = 0.0305, or 3%.
The specifications for that picoturbine use a wind velocity much higher than in urban areas to make it look good.
Thanks Ghostgum.
I see these things spinning on roofs, and know a lot of heat energy gets trapped in roof spaces, and thought maybe....
Saying it is a waste of time is a bit harsh... perhaps it is a learning experience? Either way Steven, do some more research before you spend the money on the bits from jaycar. Perhaps you could hook something up to one of the whirley birds so simulate how much load will be on it to see if it will actually spin? Stuff from around the house say, like a bike cog or something turning a chain. Stuff that wont cost you anything but time to test it out before you go out spending cash on dynamos, wiring and batteries.
There are generators made from coreless (ironless) rotors (needed to allow the whirlybird start without the magnetic coging effect standard generators exhibit) available out of china. Mounting one of these in a whirlybird does generate a small amount of power. Living near the sea I was expecting to be able to produce quite a bit of power from the sea breeze. Idea died when a block of flats appeared in front of us.
The other issue is that once some power is generated it reduces the effectiveness of the air extraction. There are solutions. Just need to find them.
Vertical axis wind turbines (VAWTs)of any type are inherently less efficient than horizontal axis wind turbines (HAWTs) because you have part of the 'blades' of the VAWT returning to the power 'stroke' against the wind. Yes I know there are ones that reduce this effect, but you can't seem to eliminate that problem.
Why do you think that almost all large commercial wind turbines are HAWTs?
If you think that whirlybirds have power to spare, try sitting next to one and applying some friction to the 'blades', it takes very little to stop them.
Then the dynamos will drive the whirlys until the battery is dead. This will teach you energy moves from higher to lower level.
sn00ze said:
Thanks Ghostgum.
I see these things spinning on roofs, and know a lot of heat energy gets trapped in roof spaces, and thought maybe....
The supposed benefit of fitting a whirlybird ventilator was once listed on the federal government's energy conservation website as one of the ten greatest urban myths. Essentially they do very little, apart from look like they are doing something.
You are right that there is a lot of trapped heat in roof spaces. The incident radiant energy is as high as 1 kW per square meter, say 100 kW even for a modest house. The trouble is that the small DIY hardware store whirlybirds don't make any significant difference to the roof temperature, even if they do help people feel like they have done something.
There is an eco architects office in Adelaide that has a properly designed ventilation system - it has 6 whirlybirds and they are over one meter in diameter and placed about 3 meters apart. I'd wager that this array actually does make a difference. Even then, if you tried to generate electricity from these, you would be negating their primary function which is to use the energy of the wind to drive a fan blade to extract the air from the roof space.
Johnmath
Excellent post.
I remember when the "Thinking Cap" roof ventilator was being advertised everywhere as the solution to house heating and cooling. I was thinking about getting a few of these installed.
Working inside my roof (drafty tiled roof with ceiling bats) on a cold but sunny Melbourne morning. It was hot in the roof even though the outside temperature as single digit. After an hour up their I was sweating a lot. A cloud moved in front of the sun and I became instantly cold and with all of the sweat on me I really felt it.
I realised that the air temperature was still single digit but I was being heated by the radiated heat from the roof tiles. As soon as the radiator is stopped the air temperature will catch up with you.
A few years later I replaced the 50 year old cement times with Terracotta and installed sarking (reflective foil) as well. The roof is no longer drafty, you cannot tell if its windy when inside the roof space. The roof space no longer varies greatly with outside air temperature.
Go for roof insulation not roof ventilation.
Thanks Baldrick.
I learn this from my own experiment. I was once living in a CBD townhouse with evaporative cooling. It had a huge Breezair unit on the corrugated iron roof. This cooler had so much capacity that I had to modify it to run at half its standard minimum speed.
I installed a “security vent” in the kitchen, both to draw the cooled air to that end of the house and to enable me to run the cooler without an open window. This of course is pressurising the air in the roof space.
I thought I would be smart and install ridge cap ventilation over the kitchen roof above the ceiling vent, and had a custom 1200 mm long ridge cap vent made. Well, bugger me, I could not feel the any air movement from this vent on a hot day with the cooler blasting at full speed!
Calculating the total open area of all of the flutes of the corrugations in the iron roof I estimated there was about one square meter of opening already in the roof. Adding another 5% open area made diddlysquat difference – doh.
My experiment was with forced ventilation. What hope has a whirlybird got? As we have seen earlier in this thread, a whirlybird has very poor ability to capture power from air movement, so has little to ability to do anything other than give the impression of doing something.
go sisalation. No holes in the roof. And if you manage to get the foil outside the wall you have the benefits that if your roof leaks the water does not drop down your ceiling or interior walls .-)