Solar Cooking Archive Discussion Forums

coconino · Joined: 21 Nov 2006 Posts: 77 Location: Sunny Brixton

I followed Joe Radabaugh's instructions to build his Heaven's Flame design and tested it yesterday on a bright and sunny March day. This was the third cooker test I've tried and it turned out to be the most successful.

Testing was done with two jars, each containing 500ml water. One jar was painted black. Readings were taken at ten-minute intervals using a hand-held digital thermometer with a bead-type thermocouple in each jar. Ambient temperature was measured using a normal household thermometer.

As can be seen from the graph, the water reached close to boiling point and the feeling amongst those observing as the test concluded was that, had the experiment started earlier, boiling point would have been achieved.

The test was conducted on Tooting Common and attracted interest from passers by (and their dogs) as well as children and teachers from a nearby school.

After four hours the test was brought to a close when it became clear that the temperature had peaked, and a pot of tea was made with the test water. It's a lot of effort for a cuppa but I was nonetheless thrilled to be able to prove the principle, and it leaves me looking forward to more testing as the sun gets stronger in the coming months.

(Thanks to JB for the photos.)

webmaster

Thanks for the wonderful report on your experiences with the Heaven's Flame cooker. It's really a great cooker. I copied two of your images for use in the Wiki here:

http://solarcooking.wikia.com/wiki/Heaven%27s_Flame
http://solarcooking.wikia.com/wiki/Paint

Please feel free to add anything more to those pages in the Wiki.

Thanks!

Tom

Brit from Norway · Joined: 27 Dec 2006 Posts: 17 Location: Norway

Great experiment and great photoes!
Regards
Brit
_________________
Best wishes to you all! Keep up the good work!

coconino · Joined: 21 Nov 2006 Posts: 77 Location: Sunny Brixton

Thanks for the nice comments! Tom, you're welcome to use the photos -- I asked the photographer. I'll try to add something to those pages when I feel inspired. There's a small report on the local school's web site too.

The weather here since last Friday has been poor, with sleet and snow and overnight frost, so I was lucky to get that good day for testing. It looked good for testing earlier today but it's a chilly 7C outside and has clouded over again. After the weekend, perhaps.

Meanwhile, I've been staying indoors and testing insulation, the results of which tests I'll be posting later.

coconino · Joined: 21 Nov 2006 Posts: 77 Location: Sunny Brixton

It was such a lovely day here today that I had to spend it outdoors and so I took the Heaven's Flame to my local park for another test. Being a sunny Easter Sunday the park was popular and this test generated a lot of interest from passers-by.

This time I decided to try cooking some staple commodities and chose brown rice, red lentils and yellow split peas. I also wanted to increase the amount of mass to be heated and so this time I used five jars, one each for the items listed and two for plain water. The quantities were as follows:

500 ml water in black-painted glass jar
700 ml water in dark-glass Hendrick's gin bottle with cork stopper
110 g brown Italian long-grain rice with 250 ml water in clear jar
60 g yellow split peas with 120 ml water in dark glass Marmite jar
50 g red lentils with 120 ml water in clear jar

The rice, peas and lentils were cooked from dry without any previous soaking, with the water being added immediately prior to the test. Temperature was taken every ten minutes using probes in (a) and (c), and the results are shown in the graph below.

I was interested to find that the curve is almost identical to that of the readings taken on 16 March. I had expected there to be a noticeable improvement in the time taken to achieve the peak temperature, particularly because this test was begun at 11:20 BST (GMT+1) which was effectively an hour earlier with regard to the sun's zenith (at 13:03 BST today). However, the greater mass being heated may be a factor, with 1.7 litres of water plus 220 grammes of solids plus three extra jars, one of which weighs 585 grammes empty, as opposed to 1 litre of water in two jars in the earlier test. At 14:09 with T1 reading 81.8C the cork stopper blew out of the gin bottle with a startling pop.

The pictures below show the set-up and the resulting cooked commodities. Once the test was completed, much of the water was used to brew tea and the cooked food was examined. The rice, peas and lentils were all thoroughly cooked and no liquid water remained except for a little in the peas. The food was tasted by those present and, although no seasoning had been added, each seemed more flavoursome than the same items cooked on the hob, particularly the yellow peas. This was attributed to the slowness of the cooking and the closed containers.

The cooked food was taken home and eaten after a little reheating and the addition of some curry seasoning, and the result was the first meal (albeit a small one) I have cooked using a solar cooker, and a fine end to this Easter Sunday.

Rice, lentils (top right) and split peas (dark jar). The orange bits in the lentils is a few uncooked (or partially-cooked) lentils showing their original colour and which must have been lodged in the threaded lid of the jar.

coconino · Joined: 21 Nov 2006 Posts: 77 Location: Sunny Brixton

I should add that today's test concluded with T1 having peaked at 94C and begun to decline. I will try to start the next test earlier in the day and attempt to get more heat into the system before noon.

Another point to note is about the odd quantities of water, grain and pulses, which was a result of initially measuring the quantities by volume rather than weight. These were:

rice = 1/2 cup in 1 cup water
peas = 1/4 cup in 1/2 cup water
lentils = 1/4 cup in 1/2 cup water

In other words, each was 2:1 by volume. Of course these are UK cups, which differ from US cups, which is why I gave the figures in metric units.