[Stoves] Powering a TLUD Fan

Thu Aug 30 19:11:59 CDT 2012

It seems that bike-powered battery chargers do exist:
http://t3.gstatic.com/images?q=tbn:ANd9GcRhAnAGE38vKDupFRBvagyVB2kgTCUZUygKHq0phUMFSx1OIGP12w&t=1
http://www.phonedog.com/2008/12/30/seriously-green-mobile-tech-the-bike-powered-battery-charger/

Thanks.
Paul Olivier

On Fri, Aug 31, 2012 at 4:29 AM, Paul Olivier <paul.olivier at esrla.com>wrote:

> Crispin,
>
> On Thu, Aug 30, 2012 at 10:22 PM, Crispin Pemberton-Pigott <
> crispinpigott at gmail.com> wrote:
>
>> Dear Friends of Fans (FoF)
>>
>> Thanks Frans and Phil. I think the fan power can be reduced on Paul O's
>> stove by increasing the length of the outer sleeve providing secondary
>> air.
>>
>
> I have experimented with changing the length of the burner housing,
>  and this is such a delicate undertaking.
>
>
>> There is little flow resistance to secondary air flow and it can be used
>> to
>> draft primary air flow to a certain extent.
>>
>> The vertical height of a stove directly affects the requirement to provide
>> primary air pressure. As the fuel packing also affects this, several
>> solutions are available to reduce the need for pressure. My point is that
>> 2
>> watts is a lot of power for a stove fan and it is worth looking at the
>> overall design to see if it is needed at all, and when. For example, it
>> may
>> be required for 5 minutes in the beginning but not after that, or 15
>> minutes, or for 1/2 the burn etc. This need impacts the battery life
>> requirement. It may be that a 'fan powered stove' only needs fan power
>> part
>> of the time. That being the case, a super capacitor might be a worthy
>> candidate because it can be charged in a few seconds.
>>
>
> In the case of rice hulls, very little power is required at the beginning
> of the burn.
> But toward the end of the burn, the power requirement at least doubles.
> Rice hull biochar provides far more resistance to the flow of air than
> rice hulls.
> Thanks.
> Paul Olivier
>
>
>
>>
>> Regards
>> Crispin
>>
>>
>>
>> Phil,
>>
>> 3x LiION  =3,7Vx3=11,1V  Charger needs 4,2x3=12,6 maximum or EXPLOSION
>> RISK
>> 2W motor at 12V-------->0,1666 A 8h xO,166A =1,8Ah Laptop cells are 3,6 Ah
>> and more Sun cell 15,6V---------> 12,6 V +3V for charging  regulator LM317
>>
>> PC  uP fans exist at 5V x0,2A=1W you could power with 2 cells; Also a dual
>> fan of 2x 1W
>>
>> Regards
>> Frans
>>
>> I see Paul Oliver's work to be excellent and appreciate how a variable
>> speed
>> fan can offer excellent control over TLUD operation. My reservation is
>> that
>> there are many places where even the small power requirement (Paul says
>> 1-2
>> watts) just isn't available. Lots of people here in Nicaragua are totally
>> off-grid and don't have reasonable access to a way to charge a battery.
>> So,
>> I am been thinking about options. Being, among other things, an
>> electronics
>> geek, here is what I have been thinking about.
>>
>>
>> Running the TLUD 8 hours a day at "average" fan speed means 12 watts per
>> day. At 12 volts that's one ampere hour. I have been thinking about a
>> couple
>> of approaches. One is "higher tech" but may be a better solution at an
>> equivalent or lower cost. In both cases I am just thinking of a
>> photovoltaic
>> panel to charge the battery. The difference is the battery voltage.
>>
>> Small PV panels are pretty common on the surplus market. For example,
>> Electronic Gold Mine (http://www.goldmine-elec.com/) offers an
>> assortment.
>> The specifications vary from 7 to 35 volts open circuit with output power
>> in
>> the range of 1-3 watts. Prices are from $4.50 to $15. As this is quantity
>> one retail price information, it is likely the could be found at
>> significantly lower costs.
>>
>>
>> As any PV-based system will need some sort of charge controller for the
>> battery and what PV cells (in particular, what voltage) will be available
>> at
>> the best price point, I am thinking that using a single-cell Lithium Ion
>> battery (3.7 volts nominal) would make the most sense. Units with a
>> capacity
>> of 2.2 ampere hours and more are commonly used in laptop computers. They
>> offer reasonable life, low cost and the possibility of finding them on the
>> surplus market. The cells can be paralleled if higher capacity is needed.
>>
>> A switching "up-converter" would be needed to supply the 12 volts needed
>> for
>> the fan. The speed control could be incorporated into the up converter
>> which
>> would reduce the cost and increase the efficiency.
>>
>> The alternative would be to use a more or less 12 volt battery (three
>> Li-Ion
>> cells in series) so that the up-converter could be eliminated. My initial
>> guess is that the reduced electronics cost would not be as much as the
>> increased battery cost but it is a viable alternative as long as higher
>> voltage surplus PV panels are available.
>>
>> While this sounds like a lot of electronics, this is all very common stuff
>> that you find in, for example, cellular phones. There is some design work
>> needed but the actual component costs will be very low.
>>
>> Comments?
>>
>> --
>> Phil Hughes
>> nicafyl at gmail.com
>>
>>
>>
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>>
>
>
> --
> Paul A. Olivier PhD
> 27C Pham Hong Thai Street
> Dalat
> Vietnam
>
> Louisiana telephone: 1-337-447-4124 (rings Vietnam)
> Mobile: 090-694-1573 (in Vietnam)
> Skype address: Xpolivier
> http://www.esrla.com/
>

-- 
Paul A. Olivier PhD
27C Pham Hong Thai Street
Dalat
Vietnam

Louisiana telephone: 1-337-447-4124 (rings Vietnam)
Mobile: 090-694-1573 (in Vietnam)
Skype address: Xpolivier
http://www.esrla.com/
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