Navigator V2 TLUD

 

 I've seen, sold, used, designed and built many different stoves over the years. The 'Navigator V2' TLUD stove in my mind is one of the best I've ever used.

 

Here are some pros

  • No patents or patents pending. This design is an adaptation for a grinder and steel tube based on the Top-Lit UpDraft (TLUD) mainframe design principles which are completely 'Open source' to use
  • Cost-effective
  • 'Green' 'Carbon negative' (produces biochar) multi-biomass fuel stove suitable for biomass pellets eg.wood and environmental biomass fuel
  • Clean emissions (Needs emission testing at 'Aprovecho Research Center' to confirm) and smokeless fire (Biomass fuels with 15% or lower moisture content are easier to burn)
  • Made from durable, high quality 304 stainless steel
  • Weld-free/no weld fabrication. Easy tube grinding with 2D laser cut pot stand (cross piece) with optional grinded pot stand
  • Depending on fuel restrictions eg.National Parks, which should be followed, possibly no more ethanol, butane, propane, white fuels eg.Shellite, petrol, diesel, kerosene etc. 
  • No pressurised and single use gas canisters or pressurised fuels for mutli-fuel stoves
  • If used for an outdoor kitchen it's an alternative to LPG and natural gas/'unnatural methane' (which produces harmful benzene emissions during combustion)
  • A great option if no electricity is available as the stove is unpowered with no electronics to potentially fail
  • If there is electricity available but not 'Green' eg. a fossil-powered grid, or reliable eg. brown outs or black outs, the stove is an alternative to electric stove tops. Could be used as a backup stove just in case or if you just like 'Carbon negative' outdoor cooking at home or away!
  • Easy to operate
  • Solid state operation (no moving parts)
  • Modular: 3 parts (tube, cross piece (2)). Billy lifters/pliers/C clamp are essential. For an outdoor kitchen I recommend using the oven tray/saucepan quench system. Optional heat shield eg.trekking
  • Suitable for a range of cooking accessories eg. 2L billy, frypan, saucepan, Kadhai wok (+inverted wok ring) etc.
  • No maintenance
  • Can be 'quenched' with water or soil

Here are some cons

  • No air->Oxygen->flame->heat control during a burn. If this is an issue and you can afford and access one, then the 'FabStove' could be a good option (too large and heavy for trekking though could be suitable for a car or permanent base camp, which could also use the 5" 'Navigator V1')
  • Probably not suitable (or allowed in more regulated Countries) for indoor use
  • Probably too heavy for 'Alpining' (plus there's the fuel access and the stove and fuel weight problem at higher altitudes - Gravity's a bitch for weight)
  • No access to or finance for tools, materials and electricity for manufacturing

Additional Technical Specifications

  • 2L billy with a 28-37m water boiling time (time after lighting the fire) using wood pellets (ambient temperature dependent)
  • 1h-1h11m burn time using wood pellets (ambient temperature dependent)
  • Maximum fuel volume and dims similar to the Permastove V4 which has been extensively and successfully tested
  • Stove weight 944g
  • Stove volume 1.62 litres
  • 98% biochar recovery ('Carbon negative') using wood pellets
  • Maximum fuel cost per burn: 15kg (bag of wood pellets)/0.64 (max wood pellet weight)=23.4 burns so at $19.95 per bag, $1.17 per burn

 

Overall, the 'Navigator V2' TLUD could be a success in the future for many use case scenarios, such as outdoor kitchens for primary or backup use, and in Australia and many other Countries where there are various camping and trekking options!

Design
- 5 x 20mm tube sections off 1m for 5 stoves
- 2 rows of primary air slots at base
- 1 row of secondary air slots 140mm above base (enough volume below for a range of feedstocks and burn times)
- 4 equidistant notches eg. 3mm x 4mm on top (for stable pot stand/cross piece placement)

-pot stand (cross piece recommended)

 

Materials
- 1m length of 4" 304 1.6mm stainless exhaust tube

 I should mention here that the 1m lengths of exhaust should be considered for prototyping, small production runs and not mass production. Also, the high quality grade of 304 exhaust tube is probably overreach for wood pellets but not for some environmental fuels.

- Pot stand: 2D laser cut 304 2.5mm cross piece (see dxf for CAD software eg.LibreCAD, below) or optional grinded pot stand off sheet metal eg.304 2.5mm

Cross piece design, 2D laser cut, 2 parts per Navigator V2 TLUD stove off 2.5mm 304 stainless steel
Cross piece.dxf
Text Document 18.7 KB

Tools
- small grinder eg.100mm (disc is 2.5mm thick)

-2D laser cutter

Personal Protective Equipment (PPE)
- goggles
- face mask/respirator (if available)
- helmet with face shield
- gloves
- cotton clothing

Build

-cut off tube sections with small grinder
- grind the primary and secondary slots and 4 top notches (for a pot stand/cross piece) with a small grinder

-pot stand: 2D laser cut cross piece OR grinded off sheet

 

Operation

-position the stove in the centre of a thick oven tray or thick bottomed saucepan on a flat surface

-fill the TLUD with fuel eg.wood pellets, rice husk pellets, bamboo, sticks etc. up to desired level to a maximum height of 10mm below the secondary air slots

-add 5 equally spaced blobs of firelighter gel (or 3 cotton wool buds soaked in kerosene)

-position the pot stand (cross piece) guided by the 4 notches

-light the stove from the top with a wooden skewer lit at one end (or a BBQ lighter)

-position the cooking accessory eg.2L billy, on top of the cross piece after 5 minutes

-ready to run without adding any additional fuel during the burn

 

At the end of the burn:

-flame goes out and usually smoke follows

-remove the cooking accessory

-water added from top eg.watering can, for initial quench of biochar pellets until oven tray/pot water level is above the primary air slots (mind the steam). Can also use soil for a 'quench', covering the top with a 50mm layer and around the primary air slots, completely blocking them (needs more testing)

-lift the TLUD vertically eg. 20cm above the oven tray/saucepan, with billy lifters/pliers/C clamp, and the biochar will fall out the bottom

-stir the biochar into the water and there will then be a complete quench

-empty the oven tray into a bucket eg. a 20L stainless one, once the tray has cooled down then it will be ready for the next burn

 

END

 

Navigator V2 testing

OK, guys. I don't think I can improve the 'Navigator V2' at this point. With a burn time of around 1 hour for wood pellets and 98% biochar recovery, I think this design strikes a good balance between DIY manufacturing, available steel, available and affordable fuel, stove weight, stove volume and a near or complete flame cap (ideal for fuel efficiency in an Oxygen limited environment for high quality biochar).

The 4th burn

- slight cross breeze
- wood pellets
- 5m startup
- 2L billy boiling time: at 33m
- burn time:1h4m
- Biochar recovery: 98%

The 5th burn

 -no wind, 9 degrees Celsius ambient temperature
- wood pellets
- 5m startup
- 2L billy boiling time: at 37m
- burn time:1h11m
- Biochar recovery: 98%

Fuel

As you can see, wood pellets have a relatively low volumetric and gravimetric energy density compared to other liquid and compressed fuels. But - in most cases produced from sawdust - a 'waste' stream from sawmills, which may or may not use sustainable forestry practices eg.FSC certified. Safer handling too than most other fuels. May need to research your pellets. In Australia, it's an emerging fuel source with a small number of options for Australian produced, affordable and large bags eg.15kg. Balancing all this, get the wood pellets that are also closest to you for the smallest logistics C footprint.

 

Alternatively, if you're in it for the long haul and can access locally produced sawdust or rice husk (or Cyanobacteria on Mars), you might consider buying a small and electrically compatible pelletiser machine that can process your biomass feedstock waste. Most of the pelletisers are from China. Not sure about their reliability. Plus there is postage cost, dubious warranties and potential customer service issues. Can be expensive but over time possibly save you money if all the ducks line up and depending on how much pellet fuel you are consuming. Bags of pellets, produced by your pelletiser, could also be locally bartered or sold.

 

More information about clean stoves can be found here, with some great info under 'Publications'.

http://aprovecho.org/resources/