[Stoves] mixing of gasses of different pressures

[Daniel]

Kirk, I just sent you some more info.... It must be real nice to have a "stoves lab".  My oxy- acetelyne tank lease ran out 2 years ago and I have not had $250 to get a new lease. Everytime I save the money something else breaks down putting me back out of work.   That pretty much means I starve because I can't fix my  snowplow, my tiller, my car exhaust.... Pardon me for being just a little bit jealous. I'm the one living the real third world lifestyle here so....

If you or anyone bring your stove to me, and show me what you are trying to do, I can fix it or tune it. I just don't travel more than a hundred miles or so at a time anymore very often. I got a nice place a mile off I--675 in Fairborn, Ohio, outside Dayton, to burn things. Paul Anderson was at my old rented lot.  None of the Stover's have seen my new " 5 acre Headwater Farm". Its got no utilities, a few sheds,  and it's literally a swamp,  ( a fen) but I'm zoned for agriculture research. .  Maybe throw a few dollars toward my welding tank fund if I show you how to fix it and you are happy. We are pretty informal here.  I'll be good with that. thanks.   Dan

Sent from my Verizon 4G LTE Droid
On Mar 4, 2019 5:40 PM, "Kirk H." <gkharris316 at comcast.net> wrote:
>
> Andrew,
>
> Thank you for your response!  I am spending some time thinking through both your response and Daniel’s.  The more I know the better I can design.
>
> I’m headed back to Aprovecho this month to test some new concepts that emerged as a result of  the TLUD summit in early February.
>
> Kirk H.
>
> Sent from Mail for Windows 10
>
> From: Andrew Heggie
> Sent: Monday, March 4, 2019 4:12 AM
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] mixing of gasses of different pressures
>
> On Tue, 26 Feb 2019 at 18:22, Kirk H. <gkharris316 at comcast.net> wrote:
>
> > I have some questions about the mixing of gasses of different pressures.
>
> This is too difficult for me to properly answer but be aware the
>
> pyrolysis offgas is actually a sol, a mixture of gases and droplets of
>
> condensed liquids, which will have a much higher mass than the gases.
>
> >This question arises from my efforts to mix wood gas and air in a
>
> TLUD-ND.  When two gasses of different pressures meet (such as higher
>
> pressure atmospheric air and lower pressure wood gas), there are two
>
> things that I can see happening.  One is that the higher pressure gas
>
> expands and compresses the lower pressure gas (expansion and
>
> compression).
>
> I think it just expands into the lower pressure gas and causes
>
> turbulence locally.
>
> >The other is that, since gasses are permeable, being mostly open
>
> space, that the molecules of the higher pressure gas penetrate in
>
> between the molecules of the lower pressure gas (I am calling this
>
> injection, since one dictionary definition describes forcing one fluid
>
> into another by using pressure).
>
> I think this diffusion happens as the injected gas loses the coherence
>
> of a jet and mixes at the boundaries, then normal gaseous diffusion,
>
> as described by Maxwell, takes place.
>
> > It seems to me that some of both will occur, some molecules hitting each other (expansion and compression) and some missing (injection).  Expansion and compression will not mix the gasses, but injection will mix them on a molecular level.
>
> but expansion of a higher pressure gas into a much larger volume of
>
> lower pressure will not involve the larger volume being compressed
>
> much, and the lower pressure we are discussing is just the buoyancy
>
> created by the gases being heated.
>
> >Injection would give excellent mixing since it brings the molecules
>
> together to react (not just folding them over into regions of each gas
>
> like turbulence).
>
> This is the same  not two different things IMO, the pressure
>
> difference that injects a stream into another results in turbulence as
>
> the boundaries interact
>
> > I have been designing my mixing system to use injection.  Does anyone know if injection actually is real?  How much penetration is possible?  Is there another name for it that I don’t know?  I think some call it entrainment, but it seems to me that entrainment is a result of injection.  Does diffusion operate at the same time across the pressure gradient?
>
> Too complicated for me to answer properly but the jet will entrain at
>
> the edges and mixing will occur , eventually the jet will have given
>
> up its kinetic energy  to the mixture and  the turbulence  will have
>
> mixed the gases. The penetration will depend on the velocity of the
>
> jet. I think diffusion will be an order of magnitude lower than  the
>
> penetration of a jet.
>
> Andrew
>
> PS Long ago I toyed with devices to aid mixing and turbulence without
>
> motors. One of the ideas was to use a steam jet, later I see Priya
>
> Karve took this up but it was lossy energy wise because  steam needs a
>
> lot of energy to change from water and also dilutes the offgas.I
>
> started looking at other ways of increasing the energy of an injected
>
> stream to create turbulence without a fan.. About the same time a
>
> stove was promoted here that had a separate container to carbonise
>
> biomass in, I forget the name,  but the energy from the pyrolysed
>
> biomass offgas was wasted.  It may still offer a means of creating a
>
> high pressure stream to drive turbulence and mixing without a fan.
>
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