Dear Mr. Kar, and to other Stovers.
Mr. Kar asked me a question, and I am sending the response to the larger audience of the Stoves Listserv and for posting onto my www.drtlud.com website.
while Jetter et al., 2012 (attached) classifies both HD4012 (Philips forced draft) and Oorja as “variations of gasifier stove”, some experts (Mukunda et al., 2011) are of the opinion that HD4012 is an in-situ combustion design while Oorja is a gasifier stove.
About your question, I basically agree with Dr. Mukunda, to whom I also send my warmest regards. The term “in-situ” correctly distinguishes the combustion from that of the TLUD gasifiers that have the migratory pyrolysis front. They can all be gasifiers (depending on the definition of gasifier), but they are not in the same categories.
There is a stove type that I call “fan-jet” stoves because high turbulence of limited air is the key feature. And they are not really top-lit. Those stoves are: Philips forced air, WorldStove Lucia forced air, Ecococina of El Salvador, and the new BioLite stoves (all have forced air, but Philips and WorldStove also have natural draft units that are sometimes confused if we do not emphasize the forced air versions.) The developers of each of those four stoves have patent claims and are for-profit companies. They are quite distinct from the TLUD stoves with fans or without.
If others want to propose a different name instead of “fan-jet”, that is fine. But do not call them “fan stoves” because there are simply too many ways to have forced air. So many different stoves with fans should not be lumped together.
The high turbulence is the way the fan-jet stoves get clean emissions, but they do NOT function (at least not very well) as a TLUD stove with the pyrolysis front moving downward in a stationary fuel pile. Fan-jet stoves have their fire (hot spot) down near the bottom, even from the beginning. That is why they can accept new amounts of fuel onto the top of the hot spot.
Note that the Oorja stove is commonly ignited as a TLUD, but once the pyrolysis front reaches the bottom, the forced air allows people to add in small amounts of fuel (I call that “trickle fueling”). But it is NOT operating any longer as a TLUD combustion device. It would be a bottom-burning stove with well controlled air. And the bottom burning is of hot charcoal, so the bottom of the stove is endangered. That is why the Oorja stoves have a cast iron cup, to prevent destruction of the lower part of the stove. The Tom Reed WoodGas Campstove is similar, but without the cup.
The above comments will be clear to those who have seen these various stoves in operation. And there does need to be a clear distinction between the various types of stoves.
[To Mr. Kar:It is a pleasure to meet you via email. At what TERI facility are you located? I am a friend of Dr. Srinivas who was in southern India (Bangalore ??) with TERI, but is now in Delhi.]
Paul / Dr TLUD
Paul S. Anderson, PhD aka "Dr TLUD" Email: psanders@ilstu.edu Skype: paultlud Phone: +1-309-452-7072 Website: www.drtlud.com
On 10/30/2012 8:42 AM, abhishek kar wrote:
Dear Dr. Anderson,
I am an Associate Fellow with The Energy and Resources Institute (TERI www.teriin.org ), India. I have been working on various technical and dissemination aspects of improved cook-stoves in India and Kenya with focus on black carbon and market value chain. I have recently published a paper on the linkage between black carbon and cookstoves (attached-Kar et al., 2012). I was also the site manager of a field research project related to black carbon mitigation- Project Surya www.projectsurya.org
As the world’s foremost authority on gasifiers for cooking applications, can you share your approach for classification of stoves as there seems to be grey areas in the classification.
For example, while Jetters et al., 2012 (attached) classifies both HD4012 (Philips forced draft) and Oorja as “variations of gasifier stove”, some experts (Mukunda et al., 2011) are of the opinion that HD4012 is an in-situ combustion design while Oorja is a gasifier stove.
Based on my limited understanding of micro-gasification, I wonder if original design intent is more relevant or style of operations that drives the
classification approach. How do we distinguish between HD4012 and Oorja if both stoves have batch fuel loading and top lit operations using same fuel type? I keenly look forward towards your expert views in this regard.Warm Regards,
Abhishek Kar
Dear Dr. Anderson,
Oorja stoves have a cast iron cup, to prevent destruction of the lower part of the stove, uses of cast iron cup to ash storage and ash collection chamber absent in HD4012 (Philips forced draft) why it absent ? it might be complete combustion of Solid fueland internal combustion chamber deign in HD4012 with ceramic tiles and these combustion chamber make it retention of heat and prevention of losses. Time of gasification period very shorter thus some people called as in- situ combustion that will be wrong.
HD4012 cook stoves also based on gasification technology ( Biomass thermal energy pathway ) and clear gas combustion flames observation can view at secondary Air after 10- 15 min at ignition of Cook Stove .
Regards
VK Singh
Dear VK Singh,
[Please note that discussions should be sent directly to my address psanders@ilstu.edu and/or via the Stoves Listserv. This website (www.drtlud.com) is not intended as a venue for discussions. Thanks.]
The use of ceramic tiles is an appropriate substitute for the cast iron cup. I do not have access to a Philips HD4012 and have only a reasonable idea of its operation. It is not a TLUD gasifier. And Philips has not provided much scientific information (not that I have seen).
Dr. Anderson
Paul S. Anderson, PhD aka “Dr TLUD”
Email: psanders@ilstu.edu
Skype: paultlud
Phone: +1-309-452-7072
Website: http://www.drtlud.com