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Adding heat storage to a KKTO

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  • Bosco_Lever
    replied
    Originally posted by Koffee_Kosmo View Post
    Don't forget -
    All owners of KKTO designs have the ability to stabilise any green bean load, be it single origin or blends by running the beans for approx 10 minutes @ Thaw to 125 C setting

    Then start the roast at Zero time as normal

    This pre roast process not only stabilises the beans and evens out the moisture content, but it also warms the beans to a level where roasting becomes easier because they have gained a head start

    KK
    I second this.
    A very simple and effective process, especially with pre-roast blends.

    Leave a comment:


  • Koffee_Kosmo
    replied
    Don't forget -
    All owners of KKTO designs have the ability to stabilise any green bean load, be it single origin or blends by running the beans for approx 10 minutes @ Thaw to 125 C setting

    Then start the roast at Zero time as normal

    This pre roast process not only stabilises the beans and evens out the moisture content, but it also warms the beans to a level where roasting becomes easier because they have gained a head start

    KK

    Leave a comment:


  • readeral
    replied
    Originally posted by MrJack View Post
    Depends somewhat on the application in question, but mostly just on whether you ask a chemical or mechanical engineer...
    Haha.

    Originally posted by Javaphile View Post
    Pretty much any engineer should have the basic concepts and math knowledge to 'solve' this as they've taken College Physics 101. They'd just have to do some digging to determine the properties of the materials they're considering.
    Hence why I continue to hassle my wife regardless! However I also did College physics... hmm. Laziness is grand.

    Leave a comment:


  • Javaphile
    replied
    Pretty much any engineer should have the basic concepts and math knowledge to 'solve' this as they've taken College Physics 101. They'd just have to do some digging to determine the properties of the materials they're considering.


    Java "Isn't Science grand?!" phile

    Leave a comment:


  • MrJack
    replied
    Originally posted by readeral View Post
    Thermodynamics and heat transfer is mechanical, isn't it? I always thought it was anyway!
    Depends somewhat on the application in question, but mostly just on whether you ask a chemical or mechanical engineer...

    Leave a comment:


  • readeral
    replied
    Thermodynamics and heat transfer is mechanical, isn't it? I always thought it was anyway! I also try to pick her brain about control systems (the PID) and she defers that one too, despite working with control systems almost daily... *shrug*

    I'll do my best to come back to this thread with helpful results. I am on Uni break in 1.5 weeks. Maybe I'll buy some cheap beans from Andy and see what I can achieve.

    Leave a comment:


  • MrJack
    replied
    For situations like this, thought experiments can take you part of the way, but trial and error is the only way to know for sure!

    Would be interested see some photos/results when you do.

    p.s. You don't need a civil engineer, you need a chemical engineer (although a mechanical engineer would probably suffice) Although it sounds like you've got a pretty good grip of the concepts for a musician.

    Leave a comment:


  • readeral
    replied
    Originally posted by Dimal View Post
    "beads" or whatever ends up in there
    It'll definitely be beads to start :P

    Oh. And to clarify - not below the floor plate to begin with. That'd be a part of the 'second step' if it ever comes to be. I can't be bothered pulling the floor out right now.

    In a sense, the way I intend to work to begin with, there will be two 'convection zones'. One within the roasting chamber, assisted by the fan force, and one below the roasting chamber, with largely natural convection (if what I say about that space below is correct - I dunno, maybe I'm wrong there!)
    However - given the space between the false floor and the bottom of the roasting chamber is so close, I might be getting a tiny bit of radiant heating (although the beads won't be red hot, so actually, probably won't...) and as the beads heat the base of the chamber, further conductive transfer (from roasting chamber) to the beans. In which case, maybe having some stainless steel balls in there would make the most sense... who knows.

    What I know is: I've bought pie weights. I'm gonna give them a crack. I'll let y'all know how it goes :P

    I keep bugging my wife about this. She keeps reminding me that she's an Electrical engineer, not a Civil engineer. I keep reminding her that I'm a musician and at least she did 1st year general engineering subjects

    Leave a comment:


  • Dimal
    replied
    Originally posted by MrJack View Post
    I would have thought that the dominant mode of heat transfer with whatever thermal mass is under the beans would be convection, not conduction. In which case, surface area is king, and beads would be ideal.
    My understanding was that the "beads" or whatever ends up in there, were going to be below the floor plate, therefore mitigating the effectiveness of any convection...

    Have a good understanding of thermodynamics as such, used to be heavily involved in coal fired thermo-generation plant design, many years ago...

    Mal.

    Leave a comment:


  • MrJack
    replied
    Originally posted by readeral View Post
    I'd be preheating it without the roasting chamber in.
    In which case, they will likely cool down during the entire roast (which might be ok).

    Leave a comment:


  • readeral
    replied
    Originally posted by MrJack View Post
    Though if you are putting them into an area which doesn't reach temperatures greater than 100°C normally, it won't help you anyway.
    I'd be preheating it without the roasting chamber in.

    Leave a comment:


  • MrJack
    replied
    Originally posted by Dimal View Post
    Probably the one thing against using beads of any kind, will be the significant interstitial spaces between the beads which will not help either heat retention or conduction. If you know of a pottery makers supply warehouse somewhere near where you are, you could see if they stock different grades of "Ceramic Grog" (not booze ). This is basically screened and graded ceramic material from a very fine almost dust-like size up to quite coarse sizes in the multiple millimetre range.

    I'd reckon that this would have to be more efficient than something like the beads.

    Mal.
    I would have thought that the dominant mode of heat transfer with whatever thermal mass is under the beans would be convection, not conduction. In which case, surface area is king, and beads would be ideal.

    In addition, ceramics generally have low thermal conductivity and often also low heat capacity (relative to metals) - which is why they are used as refractory materials (insulation).

    So perhaps some cast iron or ball bearings would be a better choice.

    Though if you are putting them into an area which doesn't reach temperatures greater than 100°C normally, it won't help you anyway.

    Leave a comment:


  • jbrewster
    replied
    Originally posted by readeral View Post
    Yeah so the beads are a first step I reckon, I'd thought about getting something made up (there's a ceramic/clay shop about 40 metres from my apartment!) but wanted a non-destructive (or at least, easily reversed) approach as a first step. Then I'd think about lowering my false floor for something more permanent.
    If you decide to go ahead, blending a large proportion of grog (as much as you can get in there and have it still hold together) into kaolin clay should give you good results, ideally you'd also get somebody to fire it in a kiln for you.

    Alternatively a commercial 'dense castable' refractory commonly used in pizza ovens and such (also, for furnaces that melt metal), could be a good option, in your application it wouldn't be necessary to actually fire it (there are binders in commercial refractory which behave like cement) ideally you'd still have some insulation on the back side though, but as you're not melting metal that's probably less of a concern

    Leave a comment:


  • readeral
    replied
    Yeah so the beads are a first step I reckon, I'd thought about getting something made up (there's a ceramic/clay shop about 40 metres from my apartment!) but wanted a non-destructive (or at least, easily reversed) approach as a first step. Then I'd think about lowering my false floor for something more permanent.

    But thanks for the suggestion! I'll look into the grog...

    Yep, we're working through the PWM options at the moment - both for element and fan. The bits and pieces around the web about TC4 and aArtisanQ are quite difficult to piece together, so can be hard to know what we need! But we're putting together a ZCD at the moment, and will pick up some new SSRs soon. Hopefully will be up and running soon!

    Leave a comment:


  • Dimal
    replied
    Probably the one thing against using beads of any kind, will be the significant interstitial spaces between the beads which will not help either heat retention or conduction. If you know of a pottery makers supply warehouse somewhere near where you are, you could see if they stock different grades of "Ceramic Grog" (not booze ). This is basically screened and graded ceramic material from a very fine almost dust-like size up to quite coarse sizes in the multiple millimetre range.

    I'd reckon that this would have to be more efficient than something like the beads.

    Also, with regard to the heating element control you have, something that incorporates a relatively high frequency Pulse Width Modulated (PWM) output control (in the high hundreds to low thousands Hz), would provide a much more granular control of the heat output from the element. There may be some mod's around for the system you already have that might be worth researching...

    Mal.

    Leave a comment:

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