[Stoves] Solar Powered Stoves Relevant?

[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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