Hi, Sefa asked me to take side-by-side photos of a mini cap and Midi-cap mounted on No.96 stoves. It is now Winter in Scotland and it was too cold for me to go outside last night. However, this morning I set up the photo-shoot as requested....the bill will follow! Here are some photos of the two stoves; on the left, an Optimus No.96 fitted with a mini-cap, and on the right, a 1937 Primus No.96 fitted with one of the new Midi-caps: Now, here is a shot of the Optimus No.96 + mini-cap by itself: and finally the Primus No.96 + Midi-cap: I hope you like the photos. Best Regards, Kerophile.
Hey George, Many thanks for the photos. I wonder if a stove with any of these silencers, gets sooner hot than with conventional roarer top? I say this as I suspect with silent damper much more flame would be touching burner's wall. Some of the heat generated would be lost due to turn to stove itself. I wonder what would happen if a desing change is considered. That is, top two rows of holes are at a height fully out of the burner wall. In this time we would get benefit full heat generated at least those 2 rows. Other bottom 2 rows can reside their current status to give some heat for the next fuel cycle. With this approach I would say midi damper should give better performance than the mini... Any parallel or counter ideas?
Hi Sefa This is an interesting question! I think that the silent damper might heat up quicker than the burner plate, but I don't think that there would be much or any difference once the stoves are at full temperature. The burner head will heat up, and this will cause the stove to self-pressurise, but I think equilibrium, or balance, would be reached where the burner head reaches a maximum operating temperature and no more. George seems to suggest that the silent dampers work really well at simmer. Could this be because they absorb more heat when the stove is running at low power, so there is lots of heat in the vapouriser to vapourise the paraffin? Anyone else?
Hi Sefa, the three options of burner which I studied on a No.96 stove all had identical primes, of a single fill of the spirit-cup. They all then ignited easily. I then waited for perhaps a minute or so, at lower power, before increasing to maximum power. I understand what you are saying about the distribution of power between the vaporisation function and direct flame heating. I am sure that this is critical with any given burner design, as there must always be sufficient heat to give the required vaporisation. If you are willing to provide additional heating to the vaporisation function, then you may be able to increase the total heat flow from a particular burner design. However, the burner head has to be able to handle the increased fuel flow, and I have found that you can over-power both the mini-cap and roarer burners at higher tank pressures.. this results in fuel-rich flames as there is insufficient surface area on the burner head for full combustion. The Midi-cap has much greater burner area and I have not been able to "overwhelm" it yet. I have dome some basic water boil trials, using the same No.96 stove and the three burner types in turn. I will make a post of the results tomorrow. Best Regards, Kerophile.
