[Stoves] kgharris stove test

Paul Anderson psanders at ilstu.edu
Wed Jun 8 08:34:12 CDT 2016


Kirk and Crispin,

I BELIEVE I understand Crispin's question of "How is the 6 kW power 
measured?"

I think the answer is that it is based on the amount of energy released 
in the measured time to bring the water to boil (that being the high 
power time-period, but the calculation has nothing to do with the 
increase in water temperature.   And that the energy measurement is 
based on the energy of the weighed fuel (adjusted for moisture content), 
and giving "credit" for the energy that is in the remaining charcoal.

Does that make sense?

Kirk and Aprovecho testing personnel:  Is that correct?

Crispin:  Were you expecting some other answer?   What other way might 
be used?

The Kirk Harris Wonderwerk TLUD stove with Strata combustor will 
certainly be a featured item at the 5-day Stove Camp on 15 - 19 August 
at Aprovecho.  Even if you cannot attend, you can give inputs and 
questions to Kirk (and to other attendees) via this Stoves Listserv.

Comment:  Kirk points out that this is a research device.   And that 
actual manufacturing with his advances is something that needs 
additional discussion and work.   THIS issue of how to put it into 
production will be an important topic at Stove Camp and here on the 
Listserv.

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu
Skype:   paultlud    Phone: +1-309-452-7072
Website:  www.drtlud.com

On 6/7/2016 11:38 PM, kgharris wrote:
> All,
> Our test stove has a power level of 1.6 to 6 kw.  What ever cooking 
> arrangment is placed on top of that will have its own 
> characteristics.  The power level experienced by the cook will depend 
> on these characteristics, and no doubt each arrangment will be 
> different from the test stove.  Each of these arrangments is valid for 
> the cooking techniques to be used.
> If anyone is interested in a very low emissions, clean TLUD-ND with 
> turn-down, then take a look at our test stove.  The principles may 
> work for you.  Test results have been presented on the list twice.
> The stove will be at Aprovecho during stove camp in August for all to 
> examine.  We will be there to answer questions about how it works and 
> to give demonstrations showing both low emissions and turn-down.  Come 
> and see for yourself.  The updated Aprovecho booklet will be available 
> soon.
> Kirk H.
>
>     ----- Original Message -----
>     *From:* Crispin Pemberton-Pigott <mailto:crispinpigott at outlook.com>
>     *To:* Stoves <mailto:stoves at lists.bioenergylists.org>
>     *Sent:* Tuesday, June 07, 2016 7:26 PM
>     *Subject:* Re: [Stoves] kgharris stove test
>
>     Dear Kirk
>
>     Thanks for those perspectives.
>
>     From your last message:
>
>     >The power level is 1.6 kw to 6kw with cushion on each end.
>
>     Do you know how these figures were obtained? You mentioned that
>     the mass change was noted every 5 minutes. It that the root of the
>     number?
>
>     You also mentioned that the high power during the test ‎was about
>     3.75 kW (?) if I recall near enough. Was this established in the
>     same manner as the 6 kW or was it taken from the WBT spreadsheet?
>
>     I would like to understand how they were determined so as to
>     compare them with future reports.
>
>     From the low power test result there should also have been a power
>     (average power) from the spreadsheet.
>
>     ‎>What ever cooking arrangment design you use is up to you and
>     heat flux will change accordingly.
>
>     Thanks for the ‎message on the side that the pot was 24.4 cm in
>     diameter. As you have a skirt on the pot the 'heated surface area'
>     is larger than the bottom's 467.6 cm^2. How high is the skirt, or
>     more exactly, how high is the portion of the pot that is enclosed
>     by the skirt when it is sitting on the stove (the skirt might
>     descend below the bottom of the pot).
>
>     For the calculation of the high power heat flux we will need to
>     know the rate of heat gain, either the peak or the average. If you
>     don't have any intermediate temperature readings that's not a
>     problem. We can use the total heat gained by the pot during the
>     hot start and the duration in seconds to get an average heat gain
>     rate. That, divided by the heated area, gives the heat gained per
>     sq cm.
>
>     If you remove the skirt, that value will change. Your comment
>     about people not using the skirt is relevant.  ‎If we are sure
>     some people will not use it, then knowing the performance in both
>     conditions would be helpful.
>
>     In the Indonesian CSI pilot there was a stove submitted with a
>     skirt. It tested well and was moved to the focus group testing.
>     The skirt was so inconvenient to use that it was rejected so the
>     stove had to be re-evaluated without it to get a new rating as the
>     subsidy level offered to the vendors is based on its performance.
>
>     The drop in performance without the skirt was statistically
>     significant so the subsidy level changed.
>
>     If you have the WBT test spreadsheet the heat flux values can be
>     calculated for both high and low power. They are based only on the
>     pot size and the energy gained and have nothing to do with the
>     fire. ‎That is an important point. The number represents the
>     cooking power experienced by the cook. It can be obtained easily
>     in the field with little equipment.
>
>     >If the people in Java can use a stove with 1.6 to 6 kw, and can use that heat effectively, then
>     the power level is adequate for Java or anywhere else.
>
>     Well therein lies the problem. The firepower is not the cooking
>     power and without the cooking power number, we don't know in
>     advance if they will accept ‎it or not. If we factor out the pot
>     size (really, the heated area) we get a cooking power per sq cm
>     [Watts]. That can be applied across all pots, or certainly all
>     similar pots so we can estimate acceptance based on social science
>     surveys indicating acceptable performance.
>
>     Because the acceptable high and low power  heat flux is culturally
>     determined, and varies from place to place, the metric has a
>     special relevance for programme implementation agents. We would
>     like to know in advance what people expect and what a candidate
>     stove can offer.
>
>     To sum up I repeat the three most important questions:
>
>     How was the 6 kW determined?
>     What is the heated area of the pot?
>     What was the average cooking power?
>
>     The last number is available from the numerator of the efficiency
>     calculation cell for any test phase - just delete the denominator
>     portion of the formula and instead divide by elapsed time in
>     seconds. ‎ The answer is in Watts.
>
>     Usually the Hot Start phase will yield the highest value.
>
>     Thanks
>     Crispin
>
>
>
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