[Stoves] Specific heat capacity/ Stove preformance data

[Crispin Pemberton-Pigott]

Dear Sarbagya

Thanks for that clarification. 

Please run a test that uses the leftover char from a previous run. That represents reality. Then see if you get about the same amount of char remaining the second time. 

Let's assume you do. 

Then use as your triplicate three tests like that in a row. There is month need to measure the char mass until the very end. 

The 'fuel consumption' is the amount of new raw fuel needed for each replication. 

The char is always fed into the subsequent fire. 

The energy available in the raw fuel is the energy consumption. It has to be compensated for moisture or course. 

Testing in this manner is 1) easier than a WBT, 2) more accurate than a WBT, 3) closer to actual behaviour and 4) automatically deals correctly with the char energy is it is removed from the process either because it can't burn in the same stove or because it was withdrawn for other purposes. As long as there is no excessive char accumulation in subsequent tests you don't even have to weigh it or worry about its actual heat content. Either a stove can burn it or it can't and the 'consumption' is the raw fuel that has to be added for each replication - only. 

I am interested to know the difference in numbers if you do this. 

You should of course divide the fuel energy by the number of litres of water boiled based on the initial mass, not the final mass because missing water was of boiled (evaporated). The effect is a few %. Always express the efficiency in terms of energy in and energy transferred (work done). 

Regards
Crispin
From BB9900

-----Original Message-----
From: "Sarbagya R. Tuladhar" <sarbagya007 at gmail.com>
Date: Tue, 13 Aug 2013 17:44:45 
To: <crispinpigott at gmail.com>; Discussion of biomass cooking stoves<stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Specific heat capacity/ Stove preformance data

Hi Crispin,

Yes, the charcoal remaining is subtracted from the initial amount of wood used. 

The stove even though can burn that char (we have done that numerous times) however for lab tests we throw it away and start with a fresh batch. The consistency in the tests are hence maintained. The wood species we use for our purpose is Casuarina with an energy value of 20,790 kJ/kg.

Cheers

Sarbagya 

On 13/08/2013, at 5:13 PM, Crispin Pemberton-Pigott wrote:

> Dear Sarbagya
> 
> Are you deducting charcoal remaining as 'wood not consumed' in that calculation?
> 
> If you are, can the stove burn that char on the next run or is it thrown away?
> 
> Please everyone note that we can't tell the real energy efficiency if we do not know the heat content of the mass of fuel. It is most helpful if the reported figure is 'the energy needed to perform the task' not the mass of fuel. We don't all use the same fuel - in fact we can all use different fuels if we report energy instead of mass. 
> 
> Thanks
> Crispin
> From BB9900
> 
> -----Original Message-----
> From: "Sarbagya R. Tuladhar" <sarbagya007 at gmail.com>
> Sender: "Stoves" <stoves-bounces at lists.bioenergylists.org>
> Date: Tue, 13 Aug 2013 14:02:30 
> To: Discussion of biomass cooking stoves<stoves at lists.bioenergylists.org>
> Reply-To: Discussion of biomass cooking stoves
> 	<stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] Specific heat capacity/ Stove preformance data
> 
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