Also, Robert Van Buskirk from Kuyere! has done some work using TECs for heating, achieving better than 100% heating efficiency (images provided below – Temperature reading is in Fahrenheit). Robert says:
“Here is what happens when you use Tec’s as pot heaters. I put four sets of three on series, and ran them at 5.5V each. They maintained a 50 to 60 degree F difference between top and bottom (i.e outside and pot).
I think this means, you get a little heat pumping, when the water temperature in the pot is less than 55 degrees higher than ambient. For Africa this should give you a water heater that can be greater than 100% efficiency when the water temperature is less than 135 deg. F (80 + 55). How much greater than 100% depends on the efficiency of heat transfer in to the cold side of the thermoelectric chip.
The TEC chips can be purchased for less than $3 each. I think the academic journals would enjoy a paper on a $50, >100% efficient solar electric hot water pot for decreasing wood burning in rural Africa. Even, if it is only %110 efficient, the >100% bit should have a little wow factor to it.”
If you look closely, you’ll notice that Robert has three TECs stacked up in each pile. He writes:
“Note, 30 minute pasteurization temperature is 145 degrees F.
I am going to try a fourth in series TEC. Then the pot may be able to maintain >100% efficiency up to pasteurization temperature.”
Please see this correspondence from Robert Van Buskirk about some ideas of TEC cooking/cooling.