Re: Temperature dilution

[AJH <andrew.heggie@dtn.ntl.com>]

On Fri, 24 May 2002 21:58:18 +1000, Peter Verhaart
<pverhaart@optusnet.com.au> wrote:

>Did Prasad really say: "it dilutes the temperature"? It gets mixed with 
>something else? Beyond me.

Prasad said:
"Two more remarks: the quantity of air to be used. Too much or too
little air
can hurt the efficiency as well as quality of combustion. That window
is
rather small. We have data on this. Hopefully it will get on the
website one
of these days."

I paraphrased:

"Prasad hinted at the fact that combustion efficiency must not be seen
only as completeness of combustion because this can be achieved at the
expense of copious amounts of excess air."

and went on to say:

"This raises the mass flow
and dilutes the temperature."
>
>How would you go about getting air at a very high temperature?

As I have said before temperature is dependant on the fuel cv and
minimising excess air, I doubt this is a good route to follow with the
stove building materials we are using as tincanium is unlikely to
survive temperatures above 700C.

> Remember 
>this is not rocket science.

I bet it's pretty similar in the combustion conditions wrt
survivability of the combustion chamber.

> If it were we could pulverise the wood and 
>inject it entrained in a flow of air (preheated if necesary). If that is 
>not hot enough we take oxygen, automatic ignition, temperature and heat 
>output rate control, none of this a problem.
>
>Alas, we stovers have to make do with what nature provides and we all know 
>nature is a poor provider. The best we can come up with is natural draft 
>and if we are really smart and inspired and lucky we might come up with 
>something that works.

I disagree that the best we can come up with is natural draught but I
may be wrong. Forced draught seems to become a necessity with
difficult fuels.
>
>I am sure, bye the way, that research on preheated air has been done for 
>industrial combustion systems. The air is not only preheated, it is also 
>given the right velocity to do its job, far beyond the capability of 
>natural draft.

Agree there
AJH

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