[Stoves] Understanding "charcoal making" stoves. Was: energy lost in charcoal making and briquetting

[Kevin Chisholm]

Dear Jeff.

Draw a "black box" around the ignited match or candle, and examine inputs 
and outputs.

What we see are:

Inputs: Fuel and air.
Outputs: Heat, products of combustion, and light from incandescent PIC's 
(Products of Incomplete Combustion).

Certainly, gasification is involved within the process, but the "big 
picture", the "overall effect", or the "end effect" of the "match or candle 
process" is products of combustion, and not a fuel gas.

In a related posting, you pose another illustrative situation:

">
> But all gasifier systems (for example WWII car/truck gasifiers) are 
> basically
> stoves as a matter of fact they were called stoves. The engine is where 
> the
> gas is burned and the engine is a heat engine. So this is basically a 
> large
> T-LUD. Gasifier and the engine is the top burner."

Similarly, if we go into "black box mode", we have two possibilities for 
analysis:

1: The Total System:

Inputs: Fuel and Air
Outputs: Mechanical power, heat, and products of combustion

The "total system" is thus a "mechanical power device". in that mechanical 
power is the desired end effect. The "total system" is not a "gasifier" in 
that there is no combustible gas in the outputs from the system. (Assuming 
of course, the total system is working as intended.)

2: System Components

The above "total system" is composed of two system components or "modules", 
or "packages":

2:1 A "gasifier" component where:
Inputs: fuel and air,
and
Outputs:   fuel gas and heat

2:2 Engine component where:

Inputs: Fuel gas and air
and
Outputs: Mechanical power, heat, and products of combustion

The engine component is a consumer of fuel gas from a gasifier component. 
Thus we see that the candle, T-LUD stove and Engine systems all contain:
a: A "gasifier component",
and
b:  A "fuel gas utilization component"... an open flame component, a burner 
component, or an "engine component"

Everyone will agree that the devices Doug Williams produces are true 
gasifiers. If we do a "black box" around his gasifiers, we see the 
following:

Inputs: Fuel and air,
and
Outputs: Fuel gas and heat

We can pose two telling questions about Doug's "true gasifier:"
Q1: Is secondary air used?
A1: No.

Q2: Will the addition of secondary air permit release of heat energy?
A2: Yes

If we ask to the same two telling questions about candles, T-LUDS and wood 
gas fueled engine systems, the answers are as follows:

Q1: Is secondary air used?
A1: Yes

Q2: Will the addition of secondary air permit release of heat energy?
A2: No.

For the sake of completeness, I will present the following definitions:
Primary Air: Air that is reacted with the primary fuel (wood)
Secondary Air: Air that is reacted with the secondary fuel (wood gas)

Best wishes.

Kevin




----- Original Message ----- 
From: "Jeff Davis" <jeff0124 at velocity.net>
To: "Discussion of biomass cooking stoves" <stoves at listserv.repp.org>
Sent: Sunday, November 05, 2006 12:56 AM
Subject: Re: [Stoves]Understanding "charcoal making" stoves. Was: energy 
lost in charcoal making and briquetting


> On Saturday 04 November 2006 10:55 pm, Kevin Chisholm wrote:
>> > Maybe Kevin talks of microcosm gasification and Paul talks of macrocosm
>> > gasification.
>>
>> Exactly the opposite!! :-) If we consider the T-LUD as a "total package" 
>> or
>> as a "macro system",
>
>
> Hi Kevin,
>
> You say that everything is a gasifier (and I have to agree) so I was 
> saying
> that a candle, match, etc. is micro (small scale) and conventional devices
> called gasifiers are macro (large scale).
>
>
> Best regards,
>
>
> Jeff
>
>
>
> -- 
> Jeff Davis
> Somewhere 20 miles south of Lake Erie, USA
> http://www.velocity.net/~jeff0124
>
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