[Stoves] The PROTOS Plant Oil Cooker

[adkarve]

Dear Peter,
I don't know if the oil would vanish without a trace. There are other
thermochemical reactions that occur in oil at high temperature. One of them
is the formation of epoxides. In deep frying, the substance that is supposed
to be fried contains water. Every time you introduce something into the pan
for frying, the temperature of the oil drops because firstly, the substance
to be fried is at room temperature. Secondly, the water in the substance
evaporates. The evaporation removes heat from the oil. To compensate for
these losses the flame intensity is deliberately kept high. If the housewife
stops introducing new material into the frying pan at a regular interval,
the oil gets overheated. Overheated cooking oil pyrolyses. To test, if
boiling oil would vanish without a trace, one would have to have a
thermostatically controlled apparatus, in which the pan is kept constantly
at 250 C.  Some residue of the epoxides and other substances may remain
behind. It is however a fact, that oil vaporizes at high temperature,
because in Indian kitchens, where deep frying is quite common,  the kitchen
wall directly behind the stove, and in case one has an exhaust fan in the
kitchen, the blades of the fan too get an oily coating.
Yours
A.D.Karve

----- Original Message -----
From: Peter Verhaart <pverhaart at iprimus.com.au>
To: Discussion of biomass cooking stoves <stoves at listserv.repp.org>
Sent: Tuesday, May 01, 2007 4:03 PM
Subject: Re: [Stoves] The PROTOS Plant Oil Cooker


> Dear A.D..
>
> Is the oil really boiling? If continued (without frying anything) will
> the oil vanish without a trace?
> For a pressurised burner of course the pressure has to be above
> atmospheric. If the above is true, would the oil vapourise without
> decomposing under pressure?
> Alas, I have no suggestions for forming a stable emulsion. Would a
> detergent work? The emulsion would ideally contain just enough water to
> form the steam needed to make a good aerosol spray. Also the water would
> probably be in the form of very small droplets, very smooths contours
> and therefore sensitive to superheating and exploding when meeting a
> solid surface, not conducive to smooth operation.
> Since the method (if it works) produces droplets and not fuel vapour,
> the spray nozzle would have to be much smaller than common in aerosol
> spray cans.
> That is all I can think of. It would be very interesting if someone
> could come up with an idea for a stable emulsion and if some experiments
> were done.
>
> With kind regards,
>
> Peter Verhaart
>
>
> adkarve wrote:
> > Dear Peter,
> > In Indian cookery, deep-frying in boiling vegetable oil is quite common.
The
> > temperature of boiling oil is 250 C. I have never observed the oil
getting
> > pyrolysed into carbon and volatile matter at that temperature, even when
the
> > same oil is used again and again, as is often done here.  However, your
> > suggestion of using a water-oil emulsion is interesting and worth
trying.
> > Have you any suggestions as to how one forms a stable emulsion of water
and
> > oil?
> > Yours
> > A.D.Karve