Waterheating

[kilone]

I aim on getting my wind turbine to partually heat the water fir the rads in my house, Firstly I am thinking about fitting the closed pumped system a 48volt DC element, the water will be continously pumped through the tank with the element in it, after being slightly heated in this way the conventinal oil boiler will do the rest, resulting in lower fuel cost as everybody now desires.

The second possible way would be, because of the low heating given by the wind turbine used in this way, could a heat exchanger be used to heat the water, if so what liquid could be used in the primary side of the exchanger to give greater  heat in the secondary side containing the water.

Last question, Am I mad ?

[Nando]

Yes you are MAD !! :>}

If you are going to use the wind mill for heating purposes, then you need to have a heater controller with MPPT to harvest the maximum power the mill has at any moment.

You can not connect a load and expect the mill to rotate, unless you get a type of controller.

Regards

Nando

[kilone]

Thanks for your  reply (and honesty (mad) )

Will you explain for me what you mean by a heater controller with MPPT,

Would it be enough to use batteries with a charge controller and dump excess to element using a voltage regulater?

[Flux]

It all depends on what you want to do.

If you already charge batteries then you can use the excess power from your charge controller to provide useful heat, you will have to dump it somewhere as heat anyway.

Unless it is a large system and you have significant periods of excess power you may not get that much heat.

If you have no need for battery storage and you just want heat then don't go the battery route.

The power from the wind increases as the cube of wind speed and if your main product is heat then you need some sort of control that lets prop speed rise with wind speed. The prop operates best with the tip speed ratio constant and if you track the power to keep the prop speed at this ideal point it is called a maximum power point tracker. With heater loads this is fairly easy to achieve.

If you need a small amount of battery power but want to make good use of heat as well, you can design the mill for heating and make a clever battery charger to cope with the variable voltage or alternatively you can make your alternator much too powerful for your battery needs, in which case it will perform badly into a battery as the battery will hold the volts and speed down and stall the prop. If now you include your heater in series with the battery you will have better performance into the battery as the prop is running at a better tip speed, you will have low losses in the alternator but you transfer these losses to your heater and make use of them.

You will still need a charge controller and that can also dump as heat when the batteries are up.

Most people just charge batteries and are not too concerned with the heat, in which case they use a smaller and cheaper alternator that is sufficient to supply the batteries in low winds. In high winds they have more than the batteries need and dump the surplus and may or may not use the heat.

There is a case for mppt control for battery charging to raise the high wind efficiency, but unless you can do something with the extra power or need the heat, there is not a lot of benefit. There is a limit to the battery capacity and if the mill can cope with light winds there will be more than enough in high winds.

This is mainly why most people manage without mppt for battery charging, it is costly, adds things to go wrong and provides little benefit. Fine for a commercial manufacturer to Quote big outputs for a given prop size, but for home build it is easier to go for a bigger prop and have the gain in low winds where it really counts.

I hope you followed some of this. What is best for you depends on your wind resource, size of machine and what your main power use is.

Flux

[kilone]

Cheers,

Am I right in the asumption that if a battery is fitted to the system and a charge controller, and i use the excess for my heat, is it true that if the battery is never drawn upon than i will have continous "excess" , is this a cheaper option as i have not use for battery power, heat generation from the turbine is my main aim.

Flux,

What type of voltage regulator could i use if i didn't fit batteries

If I can get the setup right, I will try fitting a heat exchanger with the mill heating a good heat transfer liquid eg, Thermica from Shell, to heat the water.

My lack of experience in the wind turbine field is the reason for all the questions. ,which ye guys seem to have the answers.

If anybody has tried this before maybe you could share your sucess/failings.

[Flux]

If you don't need batteries for power it would be foolish to use them, they cost money ,have a limited life and make it difficult to track the maximum power.

The only thing you need to worry about is that the voltage does not exceed the maximum rating of your heaters. If you choose things such that the power available can only bring your heaters near to full voltage at full output then you don't need any voltage control.

Heating needs an entirely different approach. You will need some sort of control, you can't just connect heaters and forget it like a battery.

You need to start with no load and switch a first stage heater on when there is enough wind to make enough power to drive it. The voltage will rise with wind speed and the power will increase with volts squared and roughly wind speed squared.

As the wind picks up you will need to add more load as the power in the wind goes up with speed cubed. You can use relays operating in a series of steps or a more complicated electronic load control.

There seems to be a lot of interest in heating all of a sudden, I am sure someone must have done it other than using the overspill from a dump load.

For heating alone it would seem logical to use ac rather than dc. DC is difficult to switch with anything other than mosfets and they are more suited to lower power and voltage. Alternators are more efficient when the output is not rectified but for good efficiency you need 3 phase and it would be necessary to keep the load between phases roughly balanced.

Flux

[Propwash]

Hi Kilone,

  I have been posting similar questions on here. I think we both have the same ideas. I just found your thread. I'll keep in touch.

[Nando]

KILONE:

Without a battery to store the energy, the wind mill generates power following the wind, so for low wind, low power for high wind, high power.

The main problem in this case is that the heating load may have a fixed value, let's say 1000 watts for a 1000 watts wind mill.

This load can not be connected directly because at low wind speed or velocity the LOW Resistive VALUE load may stall the wind mill and NO power is harvested at all.

So you need a controller that reads the available power and load the wind mill just low enough to collect the available power at that just moment and if the power varies down, the controller unload the wind mill just enough to harvest the energy available and if the power increases, the controller increases its load to harvest the energy increment at that moment.

The controller in this case needs to have the capacity of read power and adjust following the principle of MPPT ( Maximum Power Point Tracking).

So the controller presents to the wind mill a variable resistive load, following the available power in the wind mill/generator.

Does this help to understand what you need to do.

I am designing a MPPT Heater controller that I am going to offer once the PC Board is made.

Regards

Nando

[hvirtane]

I am designing

a MPPT Heater controller

that I am going to offer

once the PC Board is made.

Regards

Nando

------------------

How big will your controller be?

I mean, how big power can it

control?

- Hannu

[Propwash]

Please be tolerant of my dumb questions. Does it make sense to set up the turbine to run into a bank of batteries at a lower voltage and then use 120 volt heating elements powered by an inverter for water heating during winter months. This would allow me to have inverter power for the many times that our grid power is out. This also would allow the turbine power to be used for grid power during summer months when water heating can be done mostly by solar water heaters. I would assume if the turbine is set up for 120volts there would be no way to store the power for inverter use.

[Flux]

Yes that would work ok. You could arrange a dump controller to switch the inverter to the heaters when the batteries are charged.

It is an expensive way of doing it but if you can justify the batteries and inverter for back up use that's fine.

Remember that if you want to make any serious impact on your heating bill you need to be in a good wind area and need a large turbine. For heating other than frost protection or making a few cups of coffee a day you need at least a kilowatt coming in most of the time.

I think that if I had to do it this way I would make the alternator much too large and efficient for battery charging so that it stalled badly, and use a series heater to obtain a speed match to the prop and get it out of stall. This series heater would need to be a low resistance thing. This would contribute a significant proportion of the heating. The inverter could then come in with the 120v heaters and provide the rest of the heat when the batteries are full.

This way you could have a high efficiency alternator without the usual heating problems in the stator and it would allow you to get away with a smaller inverter.

The batteries could be modest, just big enough to take you through a power cut.

Flux

[Propwash]

Thanks Flux!!

 

[Nando]

Hannu:

The controller is a MPPT Heater controller and/or ELC Controller to limit the maximum generated voltage.

It can be used with Solar, Wind Mill, of Hydro.

One can set it as a MPPT Heater controller with maximum voltage generated ( the ELC controls the maximum voltage) or the MPPT Heater section is disabled for operation as a ELC controller.

The controller has 2 additional capabilities.

The basic controller is a PWM DC voltage controller, which requires to have a full wave rectifier to convert the AC Voltage to DC. Up to 40 amps -- all depending on the MosFet or the IGBT used.

The basic controller has a connector to feed a secondary bi-directional shift register board for additional linear ballast loads, up to 8 ballasts loads.

Depending on the bi-directional shift register board piggy-back-ballast-drivers-Board, the , the ballast drivers can be IGBT / MosFets for DC ballast control or TRIACS with Zero crossing for full wave loading.

The maximum power depends on the number of ballast drivers and the current capability of the drivers.

So, a MMPT board, another bi-directional shift register Board and a piggy back board for the shift register.

I have not decided if I make 2 different bi-directional shift register boards, one for MosFet / IGBT and the other for TRIACS, eliminating the piggy back board.

Regards

Nando

[kilone]

Hi,

Can you explain to me what you want to do, and then maybe we can compare notes,

cause I'm getting a little lost.

Ps are you building a wind turbine or have you already got one