So here's my question, or questions I guess.. I terms of burner plates, what affects does the height have on overall operation? I've raised and lowered the burner plate on my Hiker+ to adjust the flame. Just bending the legs makes adjusting it really easy. But does the burner plate position adversely affect the burners overall operation? I mean besides flame spread.. And if it does what is the optimal positioning? Second question is, does the flash point of kerosene type fuels affect the burners operation? I've ran mine with white gas (not kerosene I know), regular kerosene and ultra pure parrafin. I'm going to try Klean-Heat tonight to see how it runs. I notice the Ultra pure is louder than most other fuels and I was wondering if it's because the flash point is higher than the other fuels, thus causing the more pronounced "buzzing".. I like how clean the Ultra-Pure runs but it's expensive and turns into a really cold candle in freezing temps.. These questions are all part of my ongoing research into the nova type burner. I'm the kinda person that's always thinking "how can I make this this just a little bit better?" Those pictures were when it was new. It's been used a lot since then and been torn apart many times.. I feel sad the Hiker+ got such a bad rap. Its a great stove it you have and handyman skills.
Hi, and welcome to CCS. Let me kick off with the first question and let other members tackle the second. With these basket or cone type burners the fuel exits the jet and mixes with air to form a flammable mixture which then burns, heating your food, and also maintaining the temperature of the burner, for further vaporisation of the fuel. The main effect of varying the burner plate height is its influence on the composition of the fuel-air mixture. Raising the burner plate allows more entrainment of air, and makes the mixture "leaner", whereas lowering the burner height gives less opportunity for air addition and mixing before burning, and results in a more "fuel rich" mixture. As you have found, for any given fuel, you can fine tune the mixture to get the ideal blue flame, by altering the flame-plate height. With multi-fuel stoves, and fixed flame plates there is an inevitable compromise, and it is unlikely that one will achieve perfect stoichiometry, and the elusive perfect atmospheric blue flame, for all fuels, over the whole power range. Hope this helps. Best Regards, Kerophile.
Kerophile has provided you with a brilliant reply, Brassaxe. Plus, I was able to learn two new words today - stoichiometry and entrainment. Excellent! I find the Hiker+ to be just fine as stoves in small boxes go despite of much maligning from other users/owners. I think what I would add to the discussion is that the single jet provided with the Hiker+ is a one-size-fits-all solution. When using the heavier fuels such as diesel or kerosene, the stove will run slightly rich. When using more volatile fuels such as white gas (aka Coleman fuel or naphtha) the stove will run slightly lean. When converted to run isobutane/propane gas mixtures, the Nova burner runs quite lean, but still will support a flame. (This conversion is possible with the Nova, not the Nova+ or Hiker+.) I believe it was ArcticFlame here at CCS who experimented with using certain MSR jets to dial in a more ideal mixture of fuel/air. Some of the jets from some of the MSR stoves will fit ( a little sloppy, perhaps) in the Nova burner. I suspect that Optimus went to the one-size-fits-all jet for ease in production and because most casual users can't really tell the difference anyway. I have zero evidence to provide to support that statement - so, just my opinion. Lastly, I've tried Kleen-Heat and found it less satisfactory than standard K-1 water-white kerosene. It tends to clog and foul more than the bog-standard kero in my experience. Your mileage may vary. Just for fun... you may wish to do a Google Site Search on the term "toroidal vortex".
Thanks Kero for the info. This also brings to mind other questions.. Does lowering the height of the plate then induce more or less heat into the gas generator? I would think more, but if its running leaner it could be quite the opposite. And would that loss or gain in heat inevitably affect the vaporization of a given fuel? And this kinda brings it back around to the flash point of different fuels. For different fuels with different flash points would there be a sweet spot in terms of what type of kerosene to use? I mean if one type of fuel has a flash point of 250 and another is 150, how does that affect burner operation? I guess this is all in a quest find the best fuel, have it obtain its maximum potential if the stove is tuned right, and how to tune the stove for any that fuel. In reality I am completely happy with Ultra-pure as long as I don;t have to use my stove every day or it'll get expensive. But I really want to scour all the possible fuels for the stove and really find the best one, no questions about it. Also thanks Bernie, Yeah the Hiker+ as a stove is actually a good stove. Very durable and it works. I like it because its not cheap and I could probably modify anything I wanted on it. I would 100% agree that Optimus made it general persons stove. But with a 111 lineage at least its more of a diesel truck than a plastic chinese spork. I bought 2 gallons of Klean-heat to fill a 5L jerrycan I have sitting around, a 1L bottle and my stove. If it doesn't work in the stove i'll just use it in my lanterns. The only K-1 I can get right now is Crown 1-K from Lowes. A bit expensive for ok quality kero. I also want to get jet fuel from work just to try it... In regards to the burner I wonder if I can find blank brass threaded inserts and have different sized holes drilled in them to test myself.
Stoichiometry Entrainment. Toroidal vortex Three new words! (or is it four?) Please, Sir, my brain is full, may I be excused?...
Okay, Baja. If you'd rather see the school nurse than play ball with the other boys... Nurse Duane will see you now.
Brassaxe asked: Does lowering the height of the plate then induce more or less heat into the gas generator? I would think more, but if its running leaner it could be quite the opposite. Kerophile said the opposite: Raising the burner plate allows more entrainment of air, and makes the mixture "leaner", whereas lowering the burner height gives less opportunity for air addition and mixing before burning, and results in a more "fuel rich" mixture. Ken in NC
could this work like engines , under fuel a petrol , ie lean burn it runs hot . over fuel a diesel (nearly kero) it runs hot . just a thought kerry
Hi, there seems to be a bit of muddled thinking going on here, so let's go back to first principles. Kerophile's Combustion science 101: 1. For fire to occur, you need the triangle of combustion; Fuel, Air, and Temperature, all present. Omit any one and you do not have fire. 2. There is no direct link between flash point and energy density of the fuel. Gasoline and Kerosene have a similar energy density (the amount of energy or heat per unit mass), but very different flashpoints. 3. We have to assume that the designer of the burner of a stove drew up his design so that the specified fuels would burn under the defined operating conditions. If the fuel cannot reach its flash point it will not burn. Similarly, if he had not designed the burner to adequately vaporise the fuel under all operating conditions, he will have failed. 4 So the repeated reference to flash point is irrelevant. 5. To achieve full energy release from the combustion of a fuel you need to satisfy the temperature and ignition requirements and then ensure that all the reactants; the fuel and oxygen (from the air supply) are available in the required amounts. 6. If we are spot-on and have the correct number of oxygen atoms to combine with all the fuel atoms, and no more, we achieve stoichiometry, and thus perfect combustion. 7. If there are too many oxygen atoms for the fuel supplied, we will have a "lean" burn and waste energy in heating oxygen/air which takes no part in the combustion reaction. 8. If there are too few oxygen atoms for the fuel supplied, we have a fuel-rich combustion, and waste energy in unburnt fuel, which escapes in the exhaust. 9. As Gary has explained, Multi-fuel stoves are always a compromise. Using a single jet aperture size for all specified fuels means that combustion conditions can never be optimal for any one fuel, over the whole power range of the stove. On the other hand it might be adequate for most applications, and you do not have the hassle of jet changes for each fuel type. 10. What you are doing is experimenting in practical combustion science, and fine tuning your stove for best flame chemistry and therefore heat output. You are, of course, doing this for a single fuel type (even within the kerosene family), and jet aperture. If you change fuel type or jet size, all bets are off and you will need to re-tune. 11. The above remarks are aimed primarily at open combustion of fuel. In internal combustion engines, energy is produced in both mechanical and heat forms. Consequently the fact that lean-burning engines can run hot is not down directly to combustion science, but also involves the relative proportions of the energy emerging as useful mechanical energy, or wasted heat energy Hope this helps. Best Regards, Kerophile.
Thoughts are always muddled until you wrap your head around everything. I understand external combustion and solid fuels better than most anyone, but refining the burn on my stove requires much more study. Well so I guess most of what I was thinking is means nill, but there still is jet size adjustment and the previously mentioned burner plate adjustment. I measured the threads on the jet for my Hiker+ (Nova+) and they are M10x1 so if I find some brass plugs and a machine shop that can drill holes below 0.4mm then maybe i'll get some experiments done there. Another question is, what exactly is the cause of the buzzing noise in the combustion area. Its more pronounced with Ultra-Pure than it is with kerosene or white gas. I originally associated this with the flashpoint of the fuels since there seemed to be a correlation. But now with your reply Kero, I guess flash point has nothing to do with the combustion. So what would the source of the noise?
Hi, there is some debate as to whether it is kerosene vapour, kerosene liquid, or a mixture of the two which exits the jet. This kerosene must mix with air in the toroidal vortex before reaching the correct air-fuel mixture for combustion. It is suggested that it is the multiple separate detonations of packets of the correct mix which we hear as a buzz. In perhaps simpler burners, such as the Svea 123 the frequency of the pressure pulses is lower and the noise is more like a Helicopter. The pulse engines of the German V1 (doodlebug) rockets had an even lower frequency of detonation, and very characteristic noise...or so I am told as I haven't heard one live! http://m.youtube.com/watch?v=Q1qsBGTkVSk http://m.youtube.com/watch?v=QY308O42Ur4 Best Regards, Kerophile
I study aviation and have worked in the field for a while so maybe this will be interesting info. The engine in the V1 actually has valves that pulsate with the detonation. As the gas detonates the gasses accelerate out of the engine providing thrust and at the same time it created a vaccuum which sucked in air and fuel at the other end of the engine. The mixture was then detonated with a spark plug because the engine ran too cool and under too low of a pressure to ignite the mixture itself.. A regular pulsejet is a simple engine and can be made with cheap petal valves in a garage, newer generation pulse detonation engines (Different than pulsejet but same concept) are more digital and refined. Anyway, the sound of a V1 "doodlebug" was the result of the maximum operating frequency of the engine. Like a tuning fork but with fuel and fire.. They used to use Spitfires to take them down.. But not with bullets.. They used to flip them over... The spitfires would fly next to a doodlebug and flip it over by using its wingtip.. The gyros in the Doodlebug couldn't handle a recovery from the flip and they would just crash into the ground. They did that because firing bullets over the English mainland would be more dangerous than a crashed bomb in the countryside, and an exploding V1 would likely create a fireball and be very dangerous for the attacking pilot.. Anyway... haha So your saying the buzzing is a result of improper/proper fuel and air mixture? Is there a way to refine the stove to always be producing the proper mixture? Could it be something a different jet could resolve? Or maybe a smaller or larger burner plate? Learning all this stuff is very interesting and I thank everyone in this thread for taking the time to give me their input!
Hi, no way to refine the pulsing in my opinion, it is the nature of the beast, The fuel/air mixing occurs within the burner bell, as does subsequent ignition and combustion. Cone or basket type burners have a lot going for them in my opinion. Because most, if not all, of the fuel vaporisation is achieved after exiting the jet there is much less petroleum coke formation in the burner tubes or vaporisation chamber of the burner. This makes maintenance much easier and allows burners to operate on a wide range of otherwise "dirty" fuels such as low-quality kerosene, diesel, or even bio-diesel! Some coking will still invariably occur but most of it will be in the relatively accessible burner bell, rather than within vaporiser tubes. If you want a truly silent burner you might consider a catalytic type. Best Regards, Kerophile.
Well if the noise can't be avoided then it's fine. For me if an improvement can be made then i'm willing to give it a test. What is the best jet size for a kerosene heater? I think on hiker+ its 0.32mm? I think. And here's a question.. Does the heat shield outside the gas generator on a nova serve and particular function other than as a heat shield? I'm assuming its a heat shield...
Hi, here is a description of the Valves you refer to in relation to the V1 engine: http://aardvark.co.nz/pjet/argusv1.shtml To address your queries: The item is not a heat shield in the accepted sense of the term. The item you refer to in relation to the Nova, is in fact a windshield. When used outdoors most burners are susceptible to side draughts, which "steal" pre-heat and can effect the operating burner adversely . This is most pronounced for silent burners but roarer and basket/cone burners are also affected. In answer to you question about optimum jet aperture for kerosene burning; you have already answered your own question with the trials you have undertaken. If you had to move the flame-plate from its factory-installed position, the jet was not optimised for kerosene operation in this burner You have optimised combustion parameters using flame-height adjustment, so you do not need to fit a different jet aperture. Best Regards, Kerophile
Kerophile said: Or, if the noise of the Hiker+ stove is unpleasant to you, Brassaxe, you could... 1TMIm5Z3Fjw[/media]]YouTube Video which you could get here: Link 1 or here: Link 2 These are my original designs, copied by others, which I've set up to sell direct from the manufacturers. I make less than 10 cents on each one sold (and that, just so I can track the sales). Just a fun accessory to have if you find yourself somewhere where you'd like a stove that wasn't quite as noisy as the stock Hiker+.
So Kero, maybe I don't understand the combustion within the stove as well as you do. But the way i'm understanding it is that the plate position has the same affect on the flame and combustion as a different jet size would? I'm trying to make sure I am learning this correctly. And Bernie I have come across your caps many many many times. I still have yet to decide if I want one. I like tinkering with the original design right now. Maybe in the future. Are they cast iron or bronze? And I assume they are CNC drilled holes?
