Sue got three more quart jars of tomatoes ready, and I ran my first test with thermostat.
I still had the top blow off problem, where internal steam was generated and the caps were loosened. I realized that the very hot surface of the pot, and the small amount of water between the jar bottoms and the pot bottom, were allowing the water directly under the jars to boil first, and therefore the jars were heating the water bath, and were reaching boiling before the rest of the pot. I had saved a circular aluminum shelf from the bottom of an old pressure cooker, and will use that next time, and believe that should solve the internal pressure issues.
I could clearly hear the blup blup of the water boiling,and to my surprise, I only needed a small part of the dish to keep it boiling.
This thing is asking for a steam pressure boiler. Bet I could get some serious pressures going.
I did some energy calculations.
I put 7 quarts of water from the tap at 60F into the pot. Seven quarts weighs 14.6 lbs. I heated the water and the pot from 60F to full boil in about 30 minutes. That temperature change of 152F took 152 BTU X the 14.6 lbs or 2219 BTU/ half hour.
1KW generates 3415 BTU/ hour, so my 4438 BTU per hour dish is putting 1.3KW into the water. That was with the folding thermostat opened but still blocking some of the dish, and the mirrors needing a cleaning.
Can't wait to see what the 10 foot dish will do.
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Making small solar concentrator