[Stoves] Cooking on a Philips stove

[Paul van der Sluis]

Dear stovers,

I will try to answer all the questions raised by my previous post in one 
respons.


1) Why only the summer half year (it is actually around 8 months).

Simply because in winter I heat the house with a large woodheating 
appliance that has a provision for cooking (oven and hot plate). The 
reason I started involved in woodstoves in the first place that I could 
not use the woodheating during summertime (the hout would get too hot) and 
I wanted to be able to cook without being dependent on regular energy 
supply.

The woodheating has a thermal power of about 15 kW. Far too large and 
wastefull for cooking alone during summer. But in winter I actually cook 
on 'borrowed' heat. The heat is first used to cook and the low grade waste 
heat is subsequently used for heating the house. So I use no energy for 
cooking during the winter.

There are 3 reasons why I do not cook on the woodstove I developed during 
winter.

The inhouse heating  gives true energy free cooking.
Outdoors in winter during cooking time it is dark.
Outdoors in winter it is unpleasantly cold.

2) Can the woodstove be used for indoor heating.
In principle not. The thermal power is about 5 kW and altough emissions 
are very low they are still too high to be used in a tightly closed 
space.In fact anything more than a few candles is hazourdous to your 
health. In larger buildings I have used the stove directly below smoke 
detectors wiothout any problem, but it will still not be good for your 
health.

One could mount an open  hood above the stove, but that will suck out of 
the building a lot more air than used by the stove and net heating when it 
is cold outside will be negative.
Mounting a chiney directly on the stove will be better but makes adding 
fuel cumbersome and influences combustion efficiency. Still this would be 
the best if one has no choice.

Of course during start-up significant smoke is produced during the first 
few minutes. For indoor demo's under smoke detectors the stove is always 
on for more than 5 minutes. And quite dry wood is used. 

3) Status of the Philips project is that about 1000 stoves closely 
ressembling my prototypes have been made and sold in India. Based on the 
results it was decided to continue the project. That means a serious 
industrialisation step is now underway. I cannot disclose proces but they 
are mentioned somewhere in this discussion list

4) My stove is designed to burn charcoal once created by the gasification 
process. That makes continuous cooking possible. 'Cooking' runs of 4 hours 
are no exception in my household. The only charcoal I make is by chocking 
in a tin can the leftovers of cooking runs. 

5) The downturn ratio of the stove when using 1 size and 1 type of fuel is 
about 3 and therefore not much better than any other solid fuel stove.
 However, I can get a downturn ratio of about 20 with special attention . 
This seems a lot of work but in reality it is not. I have a box of cut 
branches (varying thicjness) and a box of charcoal next to the stove when 
I cook.
If I need really high power (7 kW) I use small twigs and the fan at high 
power. The penalty is every minute adding some fuel. So only used when I 
really need it such as baking of meat or a really quick tea.
Normal use means about 3 cm thick branches cut in about 7 cm length. Gives 
around 4kW of which typically 40% will end up in the cooking vessel.
Low power is 1-2 kW, requires about 6 cm thick branches cut in about 7 cm 
length with the fan at medium to low. A refill is required once every 
20-30 minutes
Really low power, requires the use of charcoal kept from the left overs of 
previous runs. Power can go down to 300W. A refill is required less than 
once an hour. 300W is not enough to keep a vessel boiling under windy 
conditions.

6) How does the stove compare to solar cells. For the generator part alone 
investment is comparable to solar. However, the generator needs cooling 
and an interface to the fire making it more expensive than solar. For real 
power I would just buy a solar panel. The current version just makes about 
2W. Most is used to enhance the fire properties. The typically 1 W that is 
left can be use to power a radio or some low power LEDs. Since it in 
essence is a cogeneration unit the 1 W of elecrtricity has a fuel cost of 
only 0.2g/hour.  In the stove the generator just borrows the heat from the 
fire. Virtuall all energy eventually ends up towards the cooking vessel.

7) All this beautifull technology costs money. And also the steel prices 
have gone up to such an extent that it notices. To bring down the price to 
a level where the masses who really need this stove can aford them carbon 
credits could play a role. So we are looking into that.

8) The group at the technical University is not longer active. I did meet 
a student who used to work there and who is now a collegue.

9) My cooking spot is close to the house with an overhang. So protected 
from the wind from 1 side and protected against rain.

10) I use 1 burner. Meals take normally 1-3 cooking vessels. It requires 
some planning but it is manageable. Boiling items like rice are brought to 
boiling with enough water and set aside with a towel over the vessel. In 
the meantime I can stir-fry vegetables. Set them aside with a towel on top 
. Then change to frying meat. With a bit of lucjk everything is hot and 
ready at the same time. Never had complaint about the food from my family. 
Sometimes I put on vessel 1 for a sort period before starting with vessel 
3.
After cooking I boil a few liters of water and store them in a isolated 
vessel for tea/coffe after dinner.

The reason this procedure works lies in part on the high fire power 
available: about 5 kW nominal (see also above).

11) I do the cooking primarily myself. 

12) About the cooking/frying/backing/bbq.

Cooking is clear. Frying is possible because of the high and fairly 
constant power.
For backing (pizza, bread) I made an attachment like: 
http://www.qvist.nl/AA%20ADVERTENTIES/Outback%20ovenkopie.jpg

But made from aluminum , so not collapsable. I use it with a filling of 
charcoal, the fan nearly of. It backes at around 200 Celcius for more than 
an hour.


For the bbq I use an attachment that spreads the heat, just like found in 
gas-bbqs. I use charcoal as a fill. The fun thing is it uses 1/5 the 
amount of charcoal you would normally use! The fan is set fairly high and 
the stove needs a refill every say 30 minutes.

13) The only wheather that can send me indoors is a lightning storm.  But 
they are rare and last fairly short.

14) Slow cooking is for instance the German product calle 'Pflaumen muss' 
that cooks several hours at low speed. For that I use the oven attachment. 
Works excellent with just 2 handsfull of charcoal the boiling lasts for 
more than 1 hour without any attention.

15) The largest group of people  I cooked for was 9. Thanks to the high 
fire power no issue at all.

16) From my personal interest I know what 'terra preta' is, but I find it 
hard to believe people will actively put charcoal in the soil in one place 
on earth, while others are still digging coal......


That's it for now.....

regards,

Paul.