In part 1 of this series I outlined what might be called my dream for a remote-canister Vortex Burner Stove - my solution for an ultralight winter stove. In Part 2 I covered the design and manufacture of the titanium vortex burner chamber. In this Part 3 we go into the mechanical design of the stove body and the needle valve, and then we delve deeply into the flame shape and the fuel/air requirements of a vortex burner. If you haven't read Part 1 and Part 2, do so first, because all the background to this article is given in those Parts, and is assumed here.
By "stove body" I mean the bar-like lump of aluminum which goes between the hose from the canister and the jet inside the burner chamber. You will have seen several versions of this in Parts 1 and 2. This has to provide some services listed below.
- It has to support the jet in the middle of the base plate, at the bottom (this is pretty simple).
- It has to be the connection point for the hose.
- It has to have the valve seat right near the jet, in the gas flow.
- It has to hold the screw thread for the needle valve somewhere far from the jet.
- It has to act as a heat exchanger for the liquid fuel coming out of the hose and the inverted canister.
- It has to get warm, but not so hot that the two Viton O-rings at the outer end get damaged.
A complication in the design was that I found I needed to machine all six sides of the bar, plus bore out the insides. This is not simple router-style machining like cutting out a pattern in 3-ply - but that is part of the fun with CNCs. The secret is to design suitable machining jigs and feasible machining sequences.
Needle Valve and Heat Exchanger: Theory
As you can see from all the photos, the hose connects to the stove body some distance from the jet, so the fuel has to go up the inside of the stove body, through a needle valve for control, and out through the jet. Following on from my success with the internal heat exchanger in the previous Winter Stove, I could see no reason not to do this again. That is, there will be a central bore down which the fuel will flow, but that bore will be largely filled up by the needle valve, so the fuel travels as a thin film. This is good for heat transfer and fuel vaporisation.
Read on to hear the whole story!
- Stove Body
- All About The Flames
- Fuel/Air Mixture Flammability
- Lighting the Stove
- Field Servicing and Accessing the Jet
- O-Rings and Safety
- Field Testing
- Summary so far
# of Photos: 11; Word Count: 5500