New choice for the embedded computer, the A20 from Olimex. The choice for their thermocouple boards made the switch from the Raspberry Pi as control computer easy. Now we have most of the electronics from one supplier.
Category Archives: Test Oven
How to measure reliable the amount of electricity that’s being used by the demonstration pyrolysis cell? With a couple of KW infra-red heaters not so simple especially when you want to integrate the measurements in the computerlog of the test. To test the concept I took an old transformer, replaced the old secondary winding by two windings of the 230 volt wire. Curious if I get a good potential difference on the old primary winding. The primary winding is been shorted with a 20 Ohm resistor. And the voltage over the resistor can be converted in a digital value and fed into the control computer.
Care must be taken that the secondary of a current transformer is not disconnected from its load while current is flowing in the primary, as the transformer secondary will attempt to continue driving current across the effectively infinite impedance up to its core saturation voltage. This may produce a high voltage across the open secondary into the range of several kilovolts, causing arcing, compromising operator and equipment safety, or permanently affect the accuracy of the transformer. source wikipedia
The practice is more complicated due to the load so the real RMS need to be calculated. A acs712 chip connected to an Arduino measures every cycle during one second the actual wattage that is being consumed.
TRIAC BLOCK a solid-state relay with I2C interface.
Looking for parts for our demonstration pyrolysis furnace I came across this design. Capable to regulate the 1Kw Elstein infrared heater without much effort. Controllable trough the I2C bus it connects simple to the computer that controls the furnace. Trough the link I contacted the designer and he did have spare assembled PCB’s, a deal was made and a problem solved.
The first steps towards the manual heliostat. A couple of square meters for test purposes must be doable by hand. East west the mirrors can simple pivot around their base and up and down is accomplished by a screw-thread.
With 6 mirrors the open test cell reached already 80 degrees Celsius. With the back reflector the temperature went over the 100 degrees Celsius.
From the Dutch importer of Elstein we got ten 1000 Watt modules to experiment with. They will form the heart of our first demonstration furnace.
After the ‘Proof of Principle’ and the ‘Proof of Practice’ it’s time to make a professional furnace that can be shown to the public.
The test went successful.
Only carbon remains and the carbonized bones of course, the bones are very brittle.
The highest temperature reached was 380 degrees Celsius. Ideally a higher temperature is better, the definitive pyrolysiscells must reach 500 to 600 degrees Celsius to produce as little unwanted side products as possible.
Start weight rabbit 1043 gram, the tray weights 840 gram, total weight 1883 gram.
After 15 hours on 80 degrees Celsius 1438 gram, 445 gram evaporation
The end result 1017 gram, 421 gram less then after the evaporation phase
So there remains 177 gram carbon and bones or 177/(1043/100) = 16,97%.
Stripped and prepared microwave
A broken microwave oven is the base stripped the useless parts out and closed all the holes in the oven. Made three vents pressure inlet and outlet and the outlet for gases during the pyrolysis phase.
All the newly created spaces filled up with extra insulation.
Getting a small animal to preform tests on, isn’t that simple.
The supermarket had a test rabbit nearing his ultimate sell date with 30% deduction.
And the test is underway.
Temperature set to 80 degrees with thermocouple in carcass.
Curious to see how far the evaporation of the water-content has progressed after 24 hours.
A rat experiment.
A dead rat in the garden, 184 gram, big enough to fill the little pyrolysiscell.
A bit pushing was necessary to get the rat in the cell.
Brute force approach today heating up vaporizing the water content and pyrolysis phase direct afterwards.
Shortly flammable gases start to come out of the exhaust, mostly hydrogen gas and acrolein from decomposing fat.
It is clear that animals remains don’t give nice pieces of biochar. The flesh melts when the cell membranes losing their integrity. On the left side is the skull of the rat with the front teeth is visible, the bones are very brittle. Only 24 gram remains 13% from the original 184 gram.
First fire in the big outside pyrolysis furnace. The old converted propane tank is filled with pine bark. The fire is maintained with pinecones pine needles and little twigs.