[Stoves] A debate about "efficiencies"..... was Re: ABCEG deceit and conceit

[Frank Shields]

<snip>
> On Jan 12, 2017, at 9:27 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:
> 
> 3.  On an ENERGY basis (not fuel basis), only the actual released energy in the biomass (after subtracting the energy that is still in the charcoal) should be used to calculate the heat transfer efficiency of the stove."
> 
> The heat transfer efficiency of a stove is an internal phenomenon. It is the percentage of the heat available in the gas passing the pot that makes it into the pot. To make the calculation one has to consider the energy released from the fuel, not the energy available from the fuel. That means CO, for example, and free hydrogen (H2) must be deducted from the heat available from missing (burned) fuel. It also means trying to discover the amount of energy remaining in all the fuel not burned. It is difficult to extinguish immediately on completion of the test. An error is involved. 


<snip>
The problem has been is estimating the energy left in the after mass made of wood, char, water, ash. This can’t be easily done. We need a sharp, reproducible value easily obtained from different labs. This has been the problem. 

The purpose for the testing is comparison of stoves. And it would be nice if we could use the value to transfer to what will happen with biomass found in the wild. 

Using the energy in the volatiles previously determined in the pipe is such a way. Making sure the fire goes to completeness by prodding and pocking the fuel to keep it going as long as possible until the water temperature drops, say 5 degrees(?) is easily reproduced. 

Now we have a sharp starting point (light a match) and a sharp ending point (temperature drop) and an exact total volatile energy moving past the pot as determined previously from the pipe on that fuel. If  a stove is designed such it uses energy from the char being volatilized to CO and that to CO2 at the pot and not included in the total energy - that just calculates out as a better stove. 

Moisture should not be calculated into the method. If we are comparing stoves we use oven dry fuel. If we are seeing what happens with wild fuel moisture is one of the variables that may improve or lessen the results. We want to know.

Biggest hangup is that we are stuck on the definition of ‘heat transfer efficiency’ as pertains to the Engineering books. That does not apply here because, like so many things, the natural environment too variable to accommodate engineering books. We start with a clean sheet of paper and just think about what we are trying to determine. We develop a new dictionary. 



Thanks

Frank
Frank Shields
Gabilan Laboratory
Keith Day Company, Inc.
1091 Madison Lane
Salinas, CA  93907
(831) 246-0417 cell
(831) 771-0126 office
fShields at keithdaycompany.com



franke at cruzio.com



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