[Stoves] Torrified Pellets

[Crispin Pemberton-Pigott]

Dear Dean and Camilla and All

 

Just a brief follow up after some off-line conversation:

 

The emissions rate for the stoves in Indonesia was assessed on the basis of PM and CO mass per delivered MegaJoule, in other words on the basis of emissions per unit of work done.

 

The Air Quality Guidelines from the WHO are based on the rate of emissions per unit time, and no consideration is given as to what the power of the fire is, nor the cooking power delivered into the pot. Thus all stoves are treated equally regardless of size or function.

 

Why? Because the WHO is concerned with what gets into the room, not what the stove is doing at the time. That is reasonable.

 

When it comes to the performance of the stoves for the CSI-Indonesia Pilot programme the ratings on these two metrics pace stoves in a different order because they do not have the same heat transfer efficiency and average firepower.

 

There were two stoves discussed which Camilla has identified as Prime Round and Prime Square stoves. The Prime Round has the lower PM emitted mass per MJ delivered, while the Prime Square has the lower emission rate per minute.

 

Dean further to your earlier comment about testing stoves at your Stove Camp this year, I think it would be helpful if you used the current WHO exposure model for chimney stoves. That means using an estimated average leakage of 10% of emissions, not 25%. The reason is that someone might want to know how a product would be rated under the current proposals. This applies to emissions per minute (WHO) and emissions per delivered MJ (IWA).  

 

Users of these metrics are reminded that the ‘specific’ low power metrics of “emitted mass per unit time per litre simmered” are not valid measurements of anything real so don’t use them for performance rating.  They the two metrics ‘/time’ and ‘/work done’ discussed above during a task that does not require any work to be done.

 

Regards

Crispin

 

++++++++++++

 

I agree with Crispin and Ron that gr/min needs firepower to guide stove development.

 

Best,

 

Dean

 

On Mon, May 25, 2015 at 9:53 AM, Ronald Hongsermeier <rwhongser at web.de <mailto:rwhongser at web.de> > wrote:

Dear Dean,

It appears that the parameters for the WHO PM2.5 standard is 2mg/min of _what_ _burning_ _level_ (i.e., we need a wattage parameter of some type)? When an Italian university study concluded that an average unfiltered cigarette at human-puffing speed (i.e., smoked in around 5 minutes) produced more particulate than a modern, properly running 250KW diesel engine fully loaded for an hour, it is important to link those 2 mg with an amount of fuel combusted in that minute, don't you agree? What is that parameter? Crispin obliquely referred to this earlier along in this discussion by saying to decrease particulate you just have to go to a smaller stove. There is a limit for every stove "bore" below which clean burning (however that's defined) will not be maintainable. And with airspeed (pressure differential), it's the same thing, there is an upper limit at which you will have excess air for a given bore. 

Well-made charcoal left that particulate somewhere else-- in spades -- probably in the air.

regards,
Ron
P.S. Somehow I seem to be getting a feeling that the WHO standard is not being chosen for proven health purposes, but rather for certain types of fuels to be ultimately shown to be  by definition "too dirty".  

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