The Oorja Stove, made by First Energy
, is a well designed forced-air micro-gasifier stove. The speed of the 80mm fan can be adjusted with a knob. There is a 6V 4Ah battery to deal with intermittent electric supply. We have cooked with it and it does work quite well.
We'll go through the stove, piece by piece, to inspire you in your own designs.
The most important part. It is a few pieces welded together: an inner cylinder, outer cylinder, top, bottom, a square tube, and 3 tabs on the bottom. The tube is 80mm and matches an 80mm fan. The cylinders are 4.25" and 6.5" diameter, 8" tall. The secondary air holes are 0.75" from the top.
The inner and outer cylinders each have a rectangle notched out of them. This is a good design, better than trying to intersect a circular tube through a cylindrical wall or anything like that.
This piece contributes to safety by covering the hot combustor. It also gives the stove its character and overall appearance. It is mostly 1 piece of stainless steel, bent around into an octagon. The 2 bars across the bottom are welded on, this is where the combustor sits, as well as where the feet connect.
A critical piece for the lifetime of the stove. Steel wearing down is mainly caused by hot char burning in contact with the metal. This bowl is not as tall as the inner cylinder, and doesn't have to be. After you fill the stove with pellets and let it burn down, the volume shrinks down and the char is only in the bowl, so the size is well matched.
There is a thick wall cylinder, a grate welded to the bottom, a loop in the center of the grate, and a stainless steel dish which is held by screws with spacers. Ash will fall down onto the dish.
The loop lets you pull the bowl out with an included metal hook. This makes it easy to clean out the ash.
The electronics consist of a plug, a rectifier (AC to DC), a 6V battery, a switch, a potentiometer, and an 80mm fan. It is all crammed inside a box which attaches to the outer shell with 2 screws. The rectifier (the little circuit board) is in a piece of plastic to protect it.