Dragon Heater Combustion chambers are engineered pre-built wood burning combustion chambers based on rocket heater design. They are the world's first shippable rocket heater core. They can be easily incorporated into DIY wood stoves and heaters as well as a variety of other wood fired appliances. Plans and ideas of how these combustion systems can be used can be found under plans and kits, the Dragon Notes tab at the blog site, and on the gallery tab.
Most wood burning stoves and fireplaces are horizontal feeds, that is, the wood in the combustion chamber lays down parrallel to the ground. In the J-tube Dragon Burner, the wood is fed into the combustion chamber vertically. The advantage of this approach is that only the tips of the wood burn, rather than all surfaces of the wood at once. The underlying concept behind rocket heaters is that the combustion area is kept small, and hot, so that the gases released by the burning wood are confined and consumed (virtually) completely for maximum efficiency. Because of the shape of this combustion area, it is sometimes called a J-tube.
The Dragon Burner is an improvement in the traditional J-tube rocket heater for two reasons.
1. It has an optimized design to increase turbulence. The burn tunnel in the Dragon Burner was designed by Peter van den Berg. It induces turbulence among the gases to achieve 90% combustion efficiency. The shape we have achieved in our cast burn tunnels can't be easily duplicated with bricks.
2. It also takes advantage of optimizing the materials to increase the combustion zone temperatures. The burn tunnel is made from a cast refractory material which can tolerate up to 2,600°F, has some insulative properties, and is strong enough to withstand years of poking sticks into it.
The result of all these design elements is a wood fired combustion system that burns the wood so completely that there is virtually no ash or smoke. Emissions are also extremely low because everything is "burned" prior to leaving the Dragon Burner.
Most importantly this high performance is achieved without catalytic converters or any electricity, making them an ideal choice for reliable off-grid heating.
Each burner includes a feed tube, a burn tunnel, and a heat riser. The black metal piece is the feed tube, This is where the wood is placed. It enters the combustion chamber vertically. The horizontal piece is the primary combustion zone and is called the burn tunnel, and the vanilla colored tower is the secondary combustin zone and is called a heat riser.
The burn tunnel is made from high temperature cast refractory and serves as the primary combustion chamber, a little bit like the fire box in a cast iron stove. As the wood gases mix and combust they expand very quickly and will leave the burn tunnel at a very high speed. In order to allow time for all the gases to mix and to complete combustion, a second area is needed. This is the purpose of the heat riser.
Almost all fireplaces and many cast iron stoves only have a primary combustion zone, the firebox. This means that much of the encapsulated energy of the wood is wasted since time and space was not provided for full combustion. Smoke, emmisions issues, and inefficiency typically arise from single combustion zone designs.
A secondary air intake is included just after the feed tube, to prevent backflow and improve combustion by providing extra oxygen. The air is preheated by the metal feed tube so as to not rob the combustion process by the introduction of cold air.
Note that there are thinner side attachments on 2 sides of the thicker middle area. The thicker frame fits down into the burn tunnel. The outside attachments support it and accommodate the secondary air channel. Steel may eventually burn out in this heat. We have added the extra side so that you can turn the feed tube around if one side burns out.
The tall object on the righthand side is delivered unassembled. The holes are predrilled and we supply stainless steel screws.
The object which looks like it is made from concrete has 2 pieces of ceramic fiber gasket material laid on it. These gaskets handle the differences in expansion rates between the various materials. There is also a gasket between the two halves of the casting. The straps on the outside are stainless steel which stands up to heat better than carbon steel.