[Stoves] the 150 gasifier in operation in Vietnam

Paul Olivier paul.olivier at esrla.com
Sat Mar 10 17:06:20 CST 2012


Matthew,

I wanted to compare how long it would take to bring water to a boil using
the same pan without a lid:
 one test using the 150 gasifier and the other test using a the propane
stove in my kitchen.
The propane stove in my kitchen represents an ideal premix burner.

Ron Larson asked precisely the same thing: that I try to boil water without
the dome.
I feel strongly the boiling time will at least double.
Convective heat transfer is so inefficient (as I demonstrated with my
propane burner),
 and since my burner is not a premix burner,
 the transfer of heat will far worse than my propane burner.

The big problem with a diffusion flame, as you well know,
 is that the pot has to be situated at the end of the diffusion tail.
If the pot is placed too close to the flame, the flame flares out and only
hits the edges of the bottom of the pot.
Things are quite different with the dome.

The dome rises about two inches above the gas burner, and the flame does
not flare out underneath the dome.
It does precisely the opposite: the diffusion tail comes to a single point
right at the apex of the dome.
Wind barely has an influence on what happens within the dome,
 although the dome does draw in some secondary air.
This means that the height of the dome above the burner holes is not a
major issue.

Also a dome-shaped emitter has more surface area than a flat emitter of the
same diameter.

Thanks.
Paul

On Sun, Mar 11, 2012 at 4:48 AM, Matthew Redmond <mredmond3 at gatech.edu>wrote:

> Paul,
>
> I looked into ray tracing more to see if I have access to the necessary
> software.  I have access to some, and some is open source, but either one
> would take too much time to learn right now. As the stove is (without the
> reflective aluminum foil) view factor analysis is probably plenty and ray
> tracing is overkill anyway.
>
> One question: as you stated in the biostoves list, you used a propane
> stove in your kitchen for the ~ 6 min boil test, but your gasifier for the
> ~ 3 min burn test.  Why the switch? Could you try running the gasifier
> without the screen and see how long it takes for water to boil? I'm sure
> the biostoves list would be interested in this as well.
>
> Regards,
> Matt
>
>
> On Wed, Mar 7, 2012 at 3:33 PM, Paul Olivier <paul.olivier at esrla.com>wrote:
>
>> Matthew,
>>
>> See comments.
>>
>> On Wed, Mar 7, 2012 at 7:52 PM, Matthew Redmond <mredmond3 at gatech.edu>wrote:
>>
>>> Paul,
>>>
>>> Good luck with the experiment.
>>>
>>
>> I did not have time yesterday to do the experiment with the aluminum foil.
>>
>>
>>> Though view factor can give you a good approximation, only ray tracing
>>> can give you a really accurate solution for radiation reflection, etc. This
>>> requires complex and expensive software.
>>>
>>
>> I do not know what ray tracing is.
>>
>>
>>> If all goes well with the experiment and the aluminum reflection
>>> produces good results, I could try to find a numerical estimate using ray
>>> tracing for you and see how it matches the experiment.
>>>
>>
>> I would appreciate you help with this.
>> I think that two means of reflection are needed here.
>> The first would receive the laterally emitted thermal radiation and
>> reflect it back to the pot.
>> The second would receive the downwardly reflected thermal radiation and
>> reflect it back to the pot.
>>
>> To give you a better idea of how the burner assembly is constructed, take
>> a look at the following jpegs.
>> Here you see the burner and burner housing:
>> http://dl.dropbox.com/u/22013094/150%20Gasifier/Jpegs/013.jpg
>> Here you see the wire mesh dome that it is placed on top:
>> http://dl.dropbox.com/u/22013094/150%20Gasifier/Jpegs/012.jpg
>> Here you see a close-up of the two:
>> http://dl.dropbox.com/u/22013094/150%20Gasifier/Jpegs/006.jpg
>>
>> For the laterally emitted radiation, we need an angled funnel that would
>> surround the dome.
>> For the downwardly emitted radiation, we need a slightly concave plate
>> that would sit on top of the burner.
>>
>>
>>> This will have to wait though as I am very busy right now with my
>>> studies.
>>>
>>> By the way, I see you are based in Vietnam.  Do you know Marc Pare
>>> there? Marc was a classmate of mine a few years back at Georgia Tech.
>>>
>>
>> I had invited Marc to come to Vietnam.
>> I paid his hotel each month along with most of his basic expenses.
>> He ate lunch each day at my house.
>> Then one fine day he decided to start working with several key contacts
>> of mine and left.
>> This was a strange experience.
>>
>> Thanks.
>> Paul
>>
>>
>>>
>>> Regards,
>>> Matthew
>>>
>>> On Tue, Mar 6, 2012 at 3:40 PM, Paul Olivier <paul.olivier at esrla.com>wrote:
>>>
>>>> Matthew,
>>>>
>>>> Yes, I will try today ordinary aluminum foil from my kitchen.
>>>> It will be raised a few mm's off the bottom of the burner.
>>>>
>>>> Paul
>>>>
>>>>
>>>> On Wed, Mar 7, 2012 at 3:09 AM, Matthew Redmond <mredmond3 at gatech.edu>wrote:
>>>>
>>>>> Paul,
>>>>>
>>>>>  In response to your post on using tin foil (is this the same as
>>>>> aluminum foil?) to reflect radiation from the wire mesh back up to the pot,
>>>>> it should make a difference for the better. How much of a difference is
>>>>> more complicated.  If you interested in calculating it, you should consider
>>>>> looking up some information on "View Factor Algebra."  This will help you
>>>>> approximate the difference.
>>>>>
>>>>> -Matthew
>>>>>
>>>>>
>>>>> Message: 8
>>>>> Date: Tue, 6 Mar 2012 16:45:14 +0700
>>>>> From: Paul Olivier <paul.olivier at esrla.com>
>>>>> To: Discussion of biomass cooking stoves
>>>>>        <stoves at lists.bioenergylists.org>
>>>>> Subject: Re: [Stoves] the 150 gasifier in operation in Vietnam
>>>>> Message-ID:
>>>>>        <CAOreFvbEXLfdF=
>>>>> HZPkg3-EOh5yZ_WUeD0DFqgn0e9JaYfees1Q at mail.gmail.com>
>>>>> Content-Type: text/plain; charset="iso-8859-1"
>>>>>
>>>>> Crispin,
>>>>>
>>>>> You've seen the video of the dome that is red hot.
>>>>> http://www.youtube.com/watch?v=80REBVTwpMo
>>>>> The dome emits radiant energy in all directions.
>>>>> I placed a shield on the sides of the dome to stop the lateral loss of
>>>>> radiant energy.
>>>>> You can see the shield clearly in the video.
>>>>>
>>>>> But there is a lot of radiant energy (perhaps half) that goes down to
>>>>> burner and does not heat the pot.
>>>>> I want to put a piece of tin foil about 4 mm above the burner.
>>>>> If it does not touch the burner, it should be more reflective.
>>>>> The idea is to reflect radiant energy back up in the direction of the
>>>>> pot.
>>>>> Does this make sense?
>>>>> What difference should this make?
>>>>>
>>>>> Paul
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> 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/
>>
>
>


-- 
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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