Dustin360 Senior Member Joined: 17 Feb 2011 Posts: 13 Location: San Francisco, CA Expertise: I live coffee
Posted Wed Oct 24, 2012, 8:52pm Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
Endo Said:
Thanks! Very good article. As you can read in the article "80 percent of the heat transference is via forced convection".
What side the heater should be on is another subject all together. This has much more to do with the air flow path in and around the drum and beans. I'm a lot less sure what's happening here since the air path is rather complicated on this roaster, but I suspect the testing done by Mr.Yen provides some idea.
I wasn't trying to say radiation is a major contributor in the heat transfer on the quest, only that it is a contributor. I hope im wrong, but the fact he told you that different element was on side x for a reason seems like bs. If he would of just said, "this gives you more btu's" (or whatever)I would have much less issue with it.
pngboy Senior Member Joined: 24 Jun 2011 Posts: 22 Location: Harrisonburg Expertise: I live coffee
Drip: chemex Roaster: Behmor
Posted Thu Oct 25, 2012, 3:49am Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
Very nice, looks like a good profile. Very similar looking to some of mine. I bet that it was chalked full of some nice origin flavor. I like the graph. Roastlogger doesn't have a graph yet just a live viewing of the ROR numbers witch turns red when ever it goes neg. I really like messing with the ROR at the end of the roast because you can get an ROR of 1f or 2f and stretch it out with out stalling it. But usually I'll have a ROR of about 6 or 7f after 1C.
Endo Senior Member Joined: 26 Jun 2008 Posts: 804 Location: , location, location. Expertise: I love coffee
Espresso: machine is < important than... Grinder: !
Posted Thu Oct 25, 2012, 5:15am Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
Dustin360 Said:
I wasn't trying to say radiation is a major contributor in the heat transfer on the quest, only that it is a contributor. I hope im wrong, but the fact he told you that different element was on side x for a reason seems like bs. If he would of just said, "this gives you more btu's" (or whatever)I would have much less issue with it.
I never denied radiation exists, only that its contribution is small compared to convection.
I wouldn't read too much into the "extra heat near the bean mass" comment. After all, if you we're going to boost heat and need to choose one side, it would be the one with the beans. No? Seems logical to me.
Posted Thu Oct 25, 2012, 12:02pm Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
The sawtooth pattern there is probably quantisation noise from the temperature probe - the temperature is probably only read out in 1F steps, so the RoR will be quantised to some degree. Depending on the algorithm used, the sawtooth may be smoothed out to some degree. Numerical differentiation is very sensitive to noise.
Posted Thu Oct 25, 2012, 10:02pm Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
For a good proxy of convection levels in a roaster I look at the turn-around time. A full blast fluid bed air roaster will turn-around sharply in 30-45 seconds. ( BT probe is more influenced by the air temp here) In a drum roaster with much lower air flows, turn-around is more gradual and 1.5 - 2 minutes.
The fan on the M3 looks somewhat more useful to help distribute the element heat in the roaster (much better than the Hotop here) but for better convection I would look to speed up the drum and add fins to loft the beans so they tumble more. Another option is as Arpi did on HB; add a heat gun through the trier hole.
....Not that these things are needed, but it makes a more flexible roaster.
Endo Senior Member Joined: 26 Jun 2008 Posts: 804 Location: , location, location. Expertise: I love coffee
Espresso: machine is < important than... Grinder: !
Posted Fri Oct 26, 2012, 5:03am Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
Frost Said:
...for better convection I would look to speed up the drum and add fins to loft the beans so they tumble more. Another option is as Arpi did on HB; add a heat gun through the trier hole.
The fins are longer than any I've seen. They go all the way from front to back. Are you suggesting a different pattern? How do you know it doesn't tumble well already? Have you seen inside?
Heat gun seems interesting. But way too ugly to make it into my kitchen (power tool free zone:-)
Dustin360 Senior Member Joined: 17 Feb 2011 Posts: 13 Location: San Francisco, CA Expertise: I live coffee
Posted Fri Oct 26, 2012, 10:10pm Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
Endo Said:
I never denied radiation exists, only that its contribution is small compared to convection.
I wouldn't read too much into the "extra heat near the bean mass" comment. After all, if you we're going to boost heat and need to choose one side, it would be the one with the beans. No? Seems logical to me.
Gotcha, well we are on the same page then regarding radiation. As for the element... it probably doesn't really make a difference which side it sits on. But If i were to pick a side, i would probably pick the side opposite the beans. If the spinning drum is creating a draft spinning the same direction, then putting the element on the opposite side would extend the time the hot air stays at the bottom. Hot air entering the bottom of the drum is more likely to touch the beans, vs it entering in the top. Though its probably so negligible that wouldn't matter either way.
Whats your reasoning for the bean side being better?
Endo Senior Member Joined: 26 Jun 2008 Posts: 804 Location: , location, location. Expertise: I love coffee
Espresso: machine is < important than... Grinder: !
Posted Sat Oct 27, 2012, 7:04am Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
I agree it likely doesn't make much difference. But if you look at the ET (right side) and BT (left side) temps in the drum during warmup, you do see some difference. Still, we should think of it as a heat boost, pure and simple.
I'd like to determine how many extra BTUs it adds and at what price in terms of MTBF. I will be able to see what effect it will have on roast time when I make the swap back to dual 116v next week. But I will never know the effect on reliability, unless all my 100v elements start routinely burning out. So far, it's going strong so the worries may be premature. I don't see any safety issue here since the element will simply stop heating if it fails (I assume).
oldgearhead Senior Member Joined: 25 Jan 2010 Posts: 355 Location: Go Colts! Expertise: I like coffee
Grinder: Virtuoso by Baratza Drip: Chemex,Dilongi DCM900 Roaster: 1/2K Fluid-bed
Posted Sat Oct 27, 2012, 12:38pm Subject: Re: Quest M3 Roaster - New Asymmetric Heating?
Endo Said:
I'd like to determine how many extra BTUs it adds and at what price in terms of MTBF. I will be able to see what effect it will have on roast time when I make the swap back to dual 116v next week. But I will never know the effect on reliability, unless all my 100v elements start routinely burning out. So far, it's going strong so the worries may be premature. I don't see any safety issue here since the element will simply stop heating if it fails (I assume).
In order to do that you probably need another pice of information, the resistance of each heating element. To do that you will need a device capable of measuring very low ohms. This type of ohmeter is usually found only in an electric motor repair shop, not at Lowes Home Improvement.
My best guess is: 116v element@ 116V = 600watts x 3.412 x 1.0 = 2053 BTU/hr 100v element@ 116V = 696 watts x 3.412 x .93= 2209 BTU/hr
In other words if someone else wants to duplicate your roaster, all they need to do is install an old-fashioned 60 watt light bulb....
I see what you're saying, but from the colour of the elements it seems a bit hotter than that. Maybe 2 x 60W bulbs?:-)
In any case, the why I look at it, as long as it doesn't break, I'll take what ever extra heat they'll give me. You don't have to use it all, and it certainly seems to help for roasts over 200g.
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