MIDGE stove improvements

Today was spent modifying the gasifier. After the air intake had been improved it was necessary to seal the rest of the gasifier to prevent leakage of air to where is wasn't wanted.

Previously, the combustion chamber rested precariously on four bolts attached to the outer chamber.

The weight of the combustion chamber pushed down on the bolts and allowed a sizeable air gap to appear between the top of the combustion chamber and the top lid. This gap disrupted the flow of air through the secondary air holes in the combustion chamber.

To remedy this problem the hole at the top of the cowling was widened by cutting small tabs around the circumference of the hole so that the hole the combustion chamber could just pass through. The tabs were then folded back onto combustion chamber to lock it in place.

Not only did this reduce the air gap but also meant that the supporting bolts could be removed from under the combustion chamber as the cowling now supported the combustion chamber.

A new ring of secondary air hole were drilled into the combustion chamber and the gasifier reassembled.

Another test firing was performed. The air throughput was much enhanced resulting in much higher temperatures being read.

The draught was such that red hot particles of ash were ejected from the combustion chamber. A draught control that changes the size of the primary air intake may be needed. The very bright colour of the combustion shows great heat being generated.

Future Experiments

Aluminium Foundry - Because of the immense heat being generated an experiment to melt aluminium in a crucible will be carried out. The crucible will require a lid so that the combustion chamber can be charged with additional fuel during the melt.

Automated Refuelling - During today's burn additional fuel was dropped by hand into the combustion chamber via the stove pipe. It was necessary to drop small amounts often rather than one large charge of fuel otherwise the combustion of wood gas was terminated and smoke was generated in its stead. This was remedied with a single drop of paraffin but was not ideal. An auger dropping pellets into the stove pipe would be ideal. Knowing the rate of refuelling required depends on many variables that will need to be discovered through experiment.


Make sure you take all necessary precautions. Especially when you smell a new odour. A new smell in your nostrils means something new has happened. When I returned to the house to wash my hands I noticed in the mirror that I had melted some of my hair!

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