When smoking food, the fuel (whether it's wood or charcoal) is first heated to produce smoke, and what's left over is burnt for heat. The smoke of course provides the flavor in a barbecue, but the hot gas which results from burning is flavorless.

This means that a conventional smoker has a mix of yummy smoke and flavorless hot air.

This idea is to separate, as much as possible, the production of smoke, from the production of hot air, and only expose our food to the smoke.

Here's how I expect it to work:

Wood pellets start in a hopper with a close fitting lid. When the smoker is operating, the lid should only be lifted to add more fuel.

The pellets are moved out of the bottom of the hopper into a screw conveyor -- the variant where the screw is rigidly attached to the tube, and the tube and screw rotate together.

Part of the conveyor tube is heated externally, by a fire. This of course heats the wood pellets within, causing pyrolysis. Smoke and charcoal emerge from end of the conveyer opposite the hopper.

The smoke is directed into the food cooking chamber, which is as close to airtight as possible.

After flavoring the food, the smoke is mixed with air and fuel gas (propane at first), and burnt. This fire is then used to heat the conveyor tube. Finally, the waste gas is pulled up the chimney by an electric exhaust fan.

The charcoal which falls out of the screw conveyor falls into a second hopper, which feeds into a charcoal gasifier.

In the gasifier, air is pulled through the charcoal, producing carbon monoxide, a gaseous fuel. This carbon monoxide (as soon as production of it begins) replaces the propane fuel.

To distribute heat more evenly in the food cooking chamber, a convection fan might be added (fan blades inside, motor outside of course).

To improve fuel efficiency, an economizer might be added -- a heat exchanger between the air about to be sucked out through the fan, and the air being used for combustion.

For temperature control, a computer regulates the exhaust fan speed, the rotation rate of the screw conveyor, how much air is allowed to flow through the gasifier, and the amount of propane supplied.

Users should be cautioned that concentrated wood smoke is flammable, so whenever the cooker is operating, they should be very cautious when opening the cooking chamber to add, remove, or turn food.
-- goldbb, Jun 10 2015

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