[Stoves] Solar Powered Stoves Relevant?

Wed Jul 6 21:57:47 CDT 2016

Dear Ingelore

Well, I didn’t get to criticising it as a device, it was a concept designed
by the students as a project. They donated it to an orphanage or something
in Durban. Yes, it was really expensive but that wasn’t the point. They were
trying to show that solar cooking can be done at night. 

It had wheels and was rolled indoors at night. 

Regarding the bowl, it is quite common to have institutional stoves with
fixed pots. 

Here is a Lion Stove with a 70 litre cast iron pot held in with 20mm
diameter steel bar ‘keys’ to prevent theft. Even if you want it badly, it is
really hard to take it out.

The pots are cleaned in situ, easily. They are used to it. 

Here is another cast iron pot in a solar cooker. It was our attempt to win a
BBQ competition without using any fuel.  Meal was great, judges
unappreciative.

Correctly assembled, that food on the table makes potjiekos where the potjie
is the pot.

Regards

Crispin

Hello all,

I am asking myself: Who can afford such a device? Who has the space to store
it when not in use? And - in case the in-built bowl cannot be removed -
wouldn´t it be too clumsy to clean it?

Ingelore Kahrens

Am 06.07.2016 um 22:43 schrieb Crispin Pemberton-Pigott:

Dear All Stored Heater Lovers

I have previously reported here a solar cooker that was built by German
students are Mercedes Benz in the 90’s. It was shipped to South African and
later ended up at St Joseph’s Mission near Manzini, Swaziland. I was tasked
to get it working. 

There were three of them, as I recall. The collector was a manifold of
reflector-focused copper pipes that circulated peanut oil by thermosiphon.
The storage unit was a tank of peanut oil under the collector. The cooker
was a built-in bowl that was heated from below by being in contact with the
hot peanut oil rising from below by convection. It stored a lot of heat and
could reach a temperature well over 100 C. 

Food was placed in the built-in pot and as the oil cooled, it would pass
back to the tank and hot oil would rise automatically.  Heat could be
collected all day and used for cooking in the evening.

At least that was the plan. The most serious design problem was that the
rate of oil flow past the pot was not high enough to induce a rolling boil.
It just couldn’t do it. This was the conclusion after analysing how much
heat it could deliver. There was a lot of heat available in storage, but it
couldn’t be ‘pumped out’ fast enough to give a serous cooking experience.

The options to make it work are to hand-pump the oil (easily accomplished)
or to size the components so that the heating rate was adequate to being
water to a boil and ‘boil it’. People want some form of a rolling boil.
Basically it worked, and could heat water to 100C. It was the heat flow rate
that was lacking.

If a similar system can produce a change of state with lots of latent heat,
great! Maybe the materials involved will not even be that exotic.

Regards

Crispin

Hi Daniel,

This report with the badly photo-shopped pictures turn up somewhere
periodically. You will not be able to find the product on the market – I
guess it doesn’t exist in the real world as a commercial product.

Cheers

George from the ever diminishing jungle

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Daniel-John Peterson
Sent: 06 July 2016 09:32

Hi all,

What do others think about solar powered stoves? 

It seems relevant to our cause but I worry about the pollution involved in
manufacture and disposal.

Article below refers to "the Lithium Nitrate acting as a battery storing
thermal energy for 25 hours at a time. The heat is then released as
convection for outdoor cooking."... 

http://inhabitat.com/wilson-solar-grill-stores-the-suns-energy-for-nighttime
-fuel-free-grilling/

I appologies if this is off-topic.

Daniel

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