[Stoves] Another high performance stove located

[Crispin Pemberton-Pigott]

Dear Friends of Clean Cooking

 

I have just reviewed another stove with a particulate production number that
is very low. Any test result this clean is always suspect so hold the salt
shaker, but we have more tests to analyse. 

 

The PM2.5/MJNET is between 2 and 3 mg/MJNET. That is lower than the claim
from India for LPG which is 8 mg/MJNET.

 

It is a pellet burner with power controllable across the range of 1 to 2.3
kW. That is calculated on a 3 minute smoothed average. The fuel is Albasia
Pellets which is the only type available in Central Java. The moisture level
is 5.6%. Sometimes it is a little higher, towards 8%. In the past few months
it has always been between 5.5 and 6%.

 

The importance of this is not just this particular stove, it is the
demonstration that biomass can be burned with extremely low emissions in a
relatively inexpensive natural draft stove. Remember, this is the second
stove seen recently that outperformed any fan stove I have seen.   Fans tend
to stir up particles, lofting them on the high velocity air giving elevated
PM2.5 and PM4 readings. PM4 is unusual in natural draft stoves.

 

The oft-repeated claim that a stove needs a fan in order to be 'really
clean' seems to be the old thinking now. The reduction measured against the
baseline (burning wood, not pellets) is over 99%. At this low level we have
to quibble over the precision. Let's just say that after 4 minutes from
ignition the PM level is very low.

 

The test duration is about 80 minutes and involves replication the cooking
behaviour in Central Java. The stove is made in Indonesia. 

 

The system efficiency (energy in the fuel loaded v.s. the energy in the pot)
is just over 30%. The thermal efficiency (energy in the fuel completely
combusted v.s. the energy in the pot) is just over 43%. The average Heat
Transfer Efficiency was 44.7%, with the low power average being 46.5%. 

 

Just to give you a picture of CO, the CO/CO2 ratio at low power was 1.0%,
rising with firepower. The CO/MJNET was between 3 and 4 g so it can still be
improved.

 

Regards

Crispin in Accra with a pile of friends

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