[Stoves] Help! Are there insulated biogas stoves?

Thu Nov 16 13:36:34 CST 2017

Dear Dr. Karve, Ron:

A dumb question: if the purpose of insulation is heat retention, would it
help to create a class of heat retention and/or heat transfer options
separate from stove types as such?

Heating water for bathing and laundry is one thing. I had wood- and
charcoal "samovars" with an exhaust in the middle when I was growing up. I
have also seen samovars in Afghanistan and probably Mongolia.

Smaller-scale samovars or tiffins with insulation keep the food warm and
save energy otherwise needed to re-heat the food.

Enameled cast-iron cooking pots got me thinking last night - for some types
of cooking, are they more energy-efficient (ignoring the energy in making
cast iron and enameling it)?

Another, far out, idea of energy storage is dried cooked foods, whether
dried by solar/wind, or hot gases, or some other means.

For heat transfer, I think there was some discussion here a few months ago
about steam, fuel- or solar-based.

The overall point may well be that considering the diversity of cooking and
water heating needs, we must stop boiling water or any "standard" stove
performance protocols based on metrics that are irrelevant to cooks.

Inasmuch as the distinction between cooking, water heating, and stove
heating stoves is blurry - many cookstoves serve space warming purpose
needed (i.e., in wintry weather) - some matrix of fuel quality, stove,
utensil type, insulation, heat transfer may help classify stoves better
than what Paul found in the World Bank report a couple of  years ago.

Nikhil

------------------------------------------------------------------------
Nikhil Desai
(US +1) 202 568 5831
*Skype: nikhildesai888*

On Thu, Nov 16, 2017 at 4:02 AM, Anand Karve <adkarve at gmail.com> wrote:

> Dear Ron.
>
> The gadget described by me was designed to be used as a water heater,
> using charcoal as fuel. People normally use a water heater of 20 to 40
> litre capacity. These traditional water heaters generally work on the
> principle of a samovar.  Because people use agricultural waste or garden
> waste as fuel, the traditional water heater produces a lot of smoke, and it
> is therefore operated outdoors. But in order to avoid its getting stolen,
> one brings it into the house after use and carries it out again in the next
> morning. We therefore developed a water heater which uses charcoal as fuel.
> Because charcoal burns without smoke, our device can be used indoors. But
> because indoor space is a constraint, I designed a heater having a
> relatively small water pot and a small stove. One starts the fire in the
> evening, before going to bed. The hot water in the pot gets transferred by
> heat siphon process into an insulated overhead tank. The charcoal fire does
> not need tending and it gets automatically extinguished when the charcoal
> in the stove has burned itself out. When one gets up in the morning, one
> has a barrel full of hot water.  We made various models based on this idea.
> In some, the water pot was of aluminum and in some others we used a
> stainless steel pot.  The jacket was insulated with rock wool, which is
> fire proof. The jacket enclosed the flame completely and extended for about
> 10 mm above the pot.  The gap between the water container and the jacket
> ranged from 10mm to 15mm. We never used a jacket without insulation. For
> ease of testing, we used a LPG stove. The efficiency always ranged between
> 80 and 90 percent. Two Japanese students from Nihon University worked with
> us as interns for about a month in July/August, 2017. They did the actual
> work of fabricating and testing under my guidance. I am 81 and too old and
> infirm to work with my hands.  This water heating device is still in its
> prototype stage.
>
> Yours Karve
>
> ***
> Dr. A.D. Karve
>
> Chairman, Samuchit Enviro Tech Pvt Ltd (www.samuchit.com)
>
> Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)
>
> On Thu, Nov 16, 2017 at 1:44 AM, Ronal W. Larson <
> rongretlarson at comcast.net> wrote:
>
>> AD:
>>
>> Thanks.  I can now see why this 90% value is possible with a bath water
>> heater.  One could fairly easily separate the losses associated with the
>> two water containers - by using an electric immersion heater on the larger
>> unit.  So my interest is mainly on the smaller unit and its jacket.  What
>> is the gap separation and height and the radial thickness dimension of the
>> jacket?  That should be transferable to regular cooking geometries.  Might
>> the 10% thermal loss have about 8% in this part of the heating geometry?
>> Any idea what the losses would have been if there were no jacket?
>>
>> Ron
>>
>>
>> On Nov 15, 2017, at 12:16 AM, Anand Karve <adkarve at gmail.com> wrote:
>>
>> Dear Ron,
>> I fabricated a bath water heater in which the water was heated in a 3
>> litre container. The container was sealed at the top with only the inlet
>> and outlet jutting out of the top. The inlet and outlet were joined to an
>> insulated plastic barrel of 40 litre capacity. The container to be heated
>> was surrounded by an insulated
>> jacket. Starting temperature of water was 28 C. The pot was heated on a
>> LPG stove. Hot water got transported into the insulated barrel by heat
>> siphon. Experiment was stopped when water in the barrel reached 50C.
>> Calories used were calculated on the basis of reduction in weight of LPG
>> cylinder. Calories utilised were calculated on the basis of rise in water
>> temperature in the barrel and volume of water in the barrel. Experiment was
>> repeated for 5 days, one expt a day.
>> Yours Karve
>>
>> On 15-Nov-2017 09:32, "Ronal W. Larson" <rongretlarson at comcast.net>
>> wrote:
>>
>>> AD:  cc list
>>>
>>> The 90% number here is extraordinarily high.  Ca you give more details?
>>>
>>> Ron
>>>
>>>
>>>
>>> On Nov 14, 2017, at 4:29 PM, Anand Karve <adkarve at gmail.com> wrote:
>>>
>>> Dear Karolina,
>>>
>>> The pot, which is kept on the stove, should be provided with a well
>>> insulated jacket which makes the flue gases pass through the gap between
>>> the pot and its jacket.  We obtained 90% efficiency with such pots, when
>>> tested on stoves using either LPG or charcoal. I am quite sure that it
>>> would work in the case of biogas too. The practical difficulty with this
>>> solution is that one has to have a jacket for every pot.
>>>
>>> Yours
>>>
>>> A.D.Karve
>>>
>>> ***
>>> Dr. A.D. Karve
>>>
>>> Chairman, Samuchit Enviro Tech Pvt Ltd (www.samuchit.com)
>>>
>>> Trustee & Founder President, Appropriate Rural Technology Institute
>>> (ARTI)
>>>
>>> On Mon, Nov 13, 2017 at 12:51 PM, Karolina Hagegård <
>>> karolinahagegard at gmail.com> wrote:
>>>
>>>> Hi
>>>>
>>>> I'm currently in Kenya, trying to start up a biogas company:
>>>>
>>>> https://karolinabiogas.wordpress.com/present-project/
>>>>
>>>> I'm having problems finding proper biogas stoves!
>>>>
>>>> Yesterday I had a meeting with a local stoves expert. He sells
>>>> extremely efficient insulated stoves for firewood, or the husks of
>>>> coconuts, or "any solid combustible material that you want to put in", and
>>>> he also sells completely uninsulated biogas burners. So I asked if he
>>>> wouldn't be interested in developing an insulated biogas stove for me, by
>>>> the same principle as the firewood stove he had, and I'd be selling it
>>>> together with my digesters. To my surprise, he wasn't!... He said that in
>>>> his experience, gas needs lots of air, so you couldn't insulate it... Is it
>>>> true? I told him I'd think about it and get back to him.
>>>>
>>>> This morning, I googled, WITH quotation marks, "insulated biogas
>>>> stove". There were no direct hits. I tried "insulated biogas cooker" and
>>>> "insulated biogas burners" but still no hits...
>>>>
>>>> So how is it? Is it really true that you can't make an insulated biogas
>>>> stove? What's the most energy efficient alternative I can go for?
>>>>
>>>> Most grateful for any advice!
>>>>
>>>> /Karolina
>>>> Kenya
>>>>
>>>>
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