Chengdu OE-TEX fan-assisted wood stove

Discussion in 'China' started by presscall, Dec 13, 2019.

  1. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @Simes
    Ah, right. Thanks. I’m enjoying your experimenting.
     
  2. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    I’ve used the grill a few times now and have established that the best procedure is to attach the grill pan before firing up the stove, leaving out the corrugated stainless steel drip tray and griddle screen.

    307E74F5-E2F3-47D7-9CDA-262A7914613B.jpeg


    That makes it possible to peer into the combustion chamber to check on the progress of fire starting.

    Once underway, the drip tray ...

    1D738A72-3797-4BAD-BE59-E19E74FB11E9.jpeg

    ... and griddle screen are replaced.

    DB6097DC-DCA8-4C53-A181-CFE6027826CF.jpeg

    Home made burgers perfectly done.

    905F892A-17DD-4D3E-8084-0ECC82BC9B1D.jpeg


    @Simes Granted, not as straightforward as the Biolite grill assembly for the firestarting phase, but the larger grill surface and rectangular shape gives it the edge over the Biolite’s smaller surface area oval. There’s no off-centre hot-spot as with the Biolite product and there’s more uniform heat distribution across the whole of the grill surface. It’s easier to clean too.

    The variable seed controller’s a very worthwhile refinement, from a very low draught to a turbo-boosted max to get new fuel to flame without smoking on dying embers.
     
    Last edited: Jan 21, 2020
  3. Marc

    Marc Subscriber

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    Thanks gents.

    I'm continually amazed at the usefulness and quality that's available in so many areas, for such a reasonable price.
     
  4. Simes

    Simes Subscriber

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    TLUD trial serial II.

    The first run, although a general proof of principle, was interesting but left quite a few unanswered questions. Not least was it's general practicality as a TLUD, ie unpowered, so I thought I would try the standard 'tea test' as I hadn't actually put anything on to boil.

    For the modified gassifier I had made a restrictor plate to reduce airflow, and although probably not perfectly accurate I think I had reduced grate opening area to approx 9%. So this prompted a check of ratio in the TEX, albeit the openings are in the lower inner wall. I came.to the conclusion the TEX provides approx 10% opening into the fire. I'll revisit this in the conclusions.

    The setup is as follows:

    Weather was benign, and air temp approx 5DegC
    Stove filled with 350gms pellets.
    SS camping saucepan with lid filled with 2 Imp pints cold tap water.
    Boil as.many pints as possible till all fuel is consumed. Only.using the fan once gassification had ended.
    The following is a simple timing chart, I have used the clock face timings I noted at the time.

    xx.10 - Fire lit
    xx.25 - First pan on
    xx.45 - Boiling (refill pan)
    xx.00 - Second pan boiling
    xx.15 - Third pan boiling (slight gassification droop)
    xx.35 - Fourth pan boiling
    xx.40 - gassification stops, start fan.
    xx.45 - Fifth pan boiling (embers only)
    xx.55 - Trial ends. (Sixth pan near boiling)

    Conclusions

    I thought that was pretty good, 1hr 30 mins useful burning time for the fuel quantity. Nearly 12 pints of boiling water.

    WP_20200121_12_03_42_Pro.jpg

    Just a simple action shot.

    WP_20200121_12_58_18_Pro.jpg

    Most of the soot was easily brushed off, it did start out as clean SS, the other stove would have probably hard glazed it.

    Why, with similar grate opening ratios, did the small.stove consume the fuel in less than half the time? Supposition at this point is the relative overall grate area is a significant factor as it will consume more fuel over the wider area. I will look at closing up the restrictor plate on the old stove and progessivley blank some of the holes.

    The next stage is to try the same amount of fuel with fan assist. Both to see what the changes in consumption rate are like, and if it'll heat an equivalent amount of water, and how it may improve efficiency of consuming unburnt fuel which ends up on the pan.

    @presscall @Marc @salan3
     
  5. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @Simes
    Excellent baseline for ‘powered’ trials.

    From my own observations 12 pints of water on just one combustion chamber full of fuel with the fan on throughout will be a tough challenge.

    I suspect that even with the fan on its lowest setting (with the non-stock regulator you’ve purchased Simon) a full combustion chamber would produce too fierce a flame, spilling around the pot base and wasting heat. Stoking it with fuel gradually would confer more efficient use of fuel and would replicate how I at least use the stove in reality.

    In camp, 6-pints of water in a large kettle has been about the most I’ve set to boil for washing dishes. Getting it to boil (slowly) on a kerosene wick stove makes sense while getting on with other things - eating, drinking, socialising - so getting a TLUD stove to do that in a similar amount of time makes sense.

    Mostly though, whatever the fuel efficiency of the OE stove with fan in action, a much quicker boil - or frying, or grilling session - is the primary function I envisage for it.

    So, for purpose of the trial, ‘free’ electricity for the fan from the solar panel, producing a draught of air to intensify the flame - greater, less or the same efficiency in fuel conversion to heat as without a forced draught? Tough call but I’d like to think it would be more efficient, provided fan-assisted combustion is with gradual introduction of fuel into the combustion chamber - a little and often at the lowest fan setting.

    John
     
    Last edited: Jan 22, 2020
  6. Simes

    Simes Subscriber

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    You're right of course John, it's not what I'll do with it in anger, but it's interesting to find where the limits are, and in this case it was quite informative generally. Or at least gave me some food for thought elsewhere, I need to compare fuel bed areas between the two stoves and see if there is a correlation of sorts to fuel.consumption given the other parameters. I don't remember if those factors were tested on Dr TLUD, they probably kept the fuel bed area constant for their trials.

    I've not forgotten your kettle repair sitting on Terry's homemade gassifier happily steaming away for a few hours keeping us in hot water for not a lot of wood used. Probably something I'll continue with if not using the tent stove. I' also waiting delivery of a small Valor (64?) in unknown condition for similar duties.

    I suspect, as you suggest, a full load of pellets with forced draught may be a little too agressive. Will I get more or less than 12 pints boiling in a shorter time? I've yet to find out. I'm tempted to try with the stock controller initially although even on low I think it'll get through the lot pretty quickly.

    I used the Biolite as a simple campfire under a shelter last year and it does provide a fair amount of warmth if run continuously, but as we know needs fairly constant attention, and a ready supply of coughee...wine. :)
     
  7. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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  8. Simes

    Simes Subscriber

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    Serial III - power trial

    For this one the parameters are:

    350gms pellets.

    Use stock fan controller on low setting.

    Another practical run, for this one rather than water boiling try cooking. Small GSI Dutch oven for baking, nothing critical, roasted stuffed pepper.

    Timings aren't critical just the food. :)

    WP_20200124_15_22_19_Pro.jpg

    Oiled pepper ready to start.

    WP_20200124_15_36_38_Pro.jpg

    The fire is very intensive to the point of getting the restrictor and parts of the pot supports glowing red hot.

    The fan setting uses the pellets in approx 35 mins.

    WP_20200124_15_50_40_Pro.jpg

    Pepper is nicely softened and now stuffed with prepared packet rice, plus the previous day's pepper to re heat with grated cheese.

    WP_20200124_15_50_40_Pro.jpg

    I didn't restart, just fed wood to finish the cooking.

    WP_20200124_16_02_37_Pro.jpg

    Fan driven it works extremely well and is efficient. And 20 mins later...

    Et voila

    WP_20200124_16_10_25_Pro.jpg

    They were very tasty.
     
  9. Marc

    Marc Subscriber

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    Looks delicious.
     
  10. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @Simes
    Great result.
    Moderate soot deposition on the Dutch oven I guess?
    The lower speed achievable with the add-on refinement of the variable (as opposed to 2-speed) fan speed controller reduces that jet blast quite significantly.
     
  11. Simes

    Simes Subscriber

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    @presscall, virtually none to speak of John, a result I seem to have forgotten to mention.

    Something you have also noted is the speed at which new fuel ignites without smoke. I used sticks after the pellets had been consumed. The 'low' setting I would judge to be a fair bit higher than the Biolite's. I will probably include the 'wet teabag' test in the future. I can see it consuming just about anything flammable, although paper probably isn't recommended as the you do tend to get bits of ash flying everywhere. :)

    I'm also tempted to try some of those compressed 'logs' available in supermarkets, a single giant pellet.

    If the weather remains kind I'll probably dispense with the pellets for the time being, the convenience of being able to go back indoors for 30 minutes while it's running isn't quite as essential. :)
     
  12. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    Wet wood (not too much at a time), green wood, apple cores and spent tea bags haven’t made it miss a beat.
     
  13. salan3

    salan3 United Kingdom Subscriber

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    Finally was well enough and warm enough out for me to try this out. WOW. It chucks a lot of heat out. Used pellets and the kettle was boiling very fast. The battery it came with had gone flat so used a power bank. The supplied bank is now charging.Tried the other speed controller and def the way to go. I need to sort out a box for it. @Simes which box did you end up with for them? I am wondering about de soldering the excess port.
     
  14. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @salan3
    Glad your inaugural firing of the stove went well Alan.

    I’ve been trying out a back-to-basics rival. Performance is pretty much the same, but the ‘Nomado’ resembles a starter motor, so the Chengdu certainly has the edge on looks.

    John
     
  15. Simes

    Simes Subscriber

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    Hi Alan @salan3, if you haven't deleted our off line conversation all the details are there.
     
  16. salan3

    salan3 United Kingdom Subscriber

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    I have them but thought you were looking at a smaller one?
     
  17. Simes

    Simes Subscriber

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    I've re read slowly this time, and the reference I gave is slightly too small to enclose the unit and both ports. You would need a slightly longer box to do that.

    I've opted to live with both ports being accessible, it would be fine with the larger one de soldered.
     
  18. salan3

    salan3 United Kingdom Subscriber

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    Thanks