Yet another handsfree HG setup: HG/iRB

[JavaB]

Re: Yet another handsfree HG setup: HG/iRB

Remember the ambient temperature where hes at.
Java "Knows about the cold!" phile

Mmmmm....

dont think an overheated HG will be a problem A frozen fan motor before roasting might be ;D

Takes me back to the days in Moscow (-40 degrees) where you lit a fire under the diff and gearbox to "unfreeze" them prior to driving away!!

[Corretto]

Re: Yet another handsfree HG setup: HG/iRB

If Arcticroaster sets up a fan blowing accross his bowl he will most likely have a heck of a time finishing a roast in decent times. Remember the ambient temperature where hes at.
Java "Knows about the cold!" phile

There is a nice looking fan in the original photo .............. must be used for something good

Belinda

[Thundergod]

Re: Yet another handsfree HG setup: HG/iRB

Well spotted.
And its switched to its highest setting.

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

With your roasting setup it looks like youll have a nice clear shot at the main bean mass and so the fluctuations should be quite a bit less than here. It will be interesting to hear how stable the indicated temperature is with your setup.

Hi Javaphile,
I mail-ordered the mentioned IR thermometer yesterday and I will come back to this topic once it arrived.
[Finland is a small market, so anyhting out-of-the-usual needs to be mail-ordered from elsewhere, eg Germany. Actually, my whole coffee equipment was gradually mail ordered, the LaPavoni from Italy and the grinder again from Germany. Hopeless here, or horribly expensive, eg the LaPavoni in a department store here was 300 EUR more expensive than internet offers incl. shipping. And this despite fact that Finland has highest coffee consumption/capita in the world!

Nice to see your roaster, what a machine!, I would love to hear all the sound effects this gear is making... And nice to actually SEE Minnesota, not just to HEAR about it ...

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Apart from that I did once try to see how the readings compared to the TC that is mounted in my popper, and I found that first reading would be around 10deg lower but it would range up to same reading over 10sec or so, which I thought at the time was something to do with the exhaust heat coming straight up at the IR gun.  Unfortunately I didnt wait and see if the IR gun temp kept increasing, or stabilised.
 

in one of those IR thermometer tutorials I read, it was mentioning that they typically have a 2nd IR detector to compensate for ambient temperatur / radiation inside the device itself, so one can imagine that all sort of weird things happen if there are large temp transients around the device like you suspect here.

Cheers, Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

My heat gun is usually further from the beans, than what yours appears to be, and I can conistently get first crack around 11-12 minutes and 2nd crack or the start of it around 14-17 minutes.  

Hi Bullitt,
this is one thing I was wondering: I get feeling that most of you are leaving the HG temp setting fixed, but change the distance to beans, where as I left the HG nozzle fixed around 1... 2 cm above the flowing stream of beans and then changed the temp settings eg to lower after 1 st crack.

Is there a rationale why doing it this "distance" way, other then that some HG may not have temp control ?

I presumed that the closer you come the less heat you loose, so it would be more energy efficient and save wear on the HG. Roast evenness in this case seems not be an issue after latest vane mods .

BR Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi Bullitt, JavaB, Javaphile, Coretto et al.,

thanks again for debugging my setup here from 10,000 Miles distance, I really feel I am on a steep learning curve thanks to you ..

Attached is pic of the latest version of setup.

You see a metal net on the drill air inlet, actually good, Bullitt you reminded of the drill, I wasnt aware that the air-inlet was right above the brushes which is not the optimum location to ingest a lot of chaff ...
The metal nets were cut out from a teasieve  ;D

And now the fan blows in Coretto-style at the HG (the simple and best ideas are the ones most difficult to see ...) and seems to prevent chaff getting into the HG. HG stays nicely cool, but maybe this 45 deg HG angle relative to the vertically rising plume of hot hear also helps to prevent much hot air appearing at the inlets in the first place.
Added bonus of this cooling arrangements is that it will also keep the IR thermomemter cool which will be also mounted at
the notestander upwind right into the fan airstream.

And with 6 deg C outside  temp the 200g roast still worked well, now 1 st crack at the planned 9 min, roast within 2nd crack off after 18 min. And I use only max 70% power setting on HG, mostly 50%, so maybe it will live for a while.

Now, with the latest vane tweaking  the roast is really even, for those who demand proof I added the pics xxx_roast5.jpg to the server.

Oh, and best of all, the home-roasted coffee DOES taste better!

Cheers Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi again,

the day is not yet over here in arcticland ...

When pondering about how to evolve HG/iRB into something which can really cope with arctic temps, like -20 C its clear some sort of lid is needed in order to trap the heat. But which ?

Then came this brainwave that I had somewhere a TRANGIA camping cookset stashed away and voila! ready is the truely arctic HG/iRB   Or is it now a classical (inclined) drum roaster, who can tell ?

The amzing fun in this is that no modifications were required: this alu-lid enclosure fits perfectly on top of the vane attachments, no screws , nothing. HG still uses the nozzle, but its now higher above the bean bed and will warm the whole chamber. I expect more even roasts and lower power settings on the HG => longer life!?.

Smoke can vent out through the many holes and you can still peak through the center hole to see whats going on inside.

Now the HG is even better protected from the heat and one can nevertheless fully blast it now with the Corretto HG-fan arrangement as it will not cool the roasting chamber.

I cant wait to run this baby!

Cheers, Peter

P.S. More pics on the server

P.S:S: this belongs to another thread, but I think this principle may also be the way to go for any IR heating schemes. From physics principles in order to get efficient IR heating you should enclose the beans by IR refelective surfaces and inject IR radiation into such enclosure.
Thats exactly like a microwave oven: you have a MW reflective enclosure (cavity) and in middle the absorbing target to heat. No other absorbers like metal allowed. MW radiation from magnetron is conducted into the chamber via waveguide.
Same for IR, we need a reflective chamber, have a large bean surface to speed up the radiative heat transfer and we need mechanical bean agitation as air agitation would cool them down. The tricky thing in this IR reflective chamber is the smoke which will absorbe the IR and spoil the walls, they wont be a radiative barrier eny more and instead heat up (losses). So we must somehow vent the smoke out. Now all we need is to replace the HG by a strong IR source and channel the radition with a reflective  aluminium duct into such enclosure as in pic. some mild fan will need to vent the smoke out.
Ideas, ideas

[Thundergod]

Re: Yet another handsfree HG setup: HG/iRB

the day is not yet over here in arcticland ...

Wait a minute.
Arent the days there 6 months long?




Awesome addition by the way.

[JavaB]

Re: Yet another handsfree HG setup: HG/iRB

Wait a minute.
Arent the days there 6 months long?
Awesome addition by the way.

Wow...

Imagine waiting 3 days for the roast to mature ;D ;D ;D

It would be a long time between drinks!

Love the roaster by the way - just a bit harder to see the beans now but awesome heat retention.

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

 
Takes me back to the days in Moscow (-40 degrees) where you lit a fire under the diff and gearbox to "unfreeze" them prior to driving away!!

Hhhm, you mean something like this ?

Artic booster, or a gas-fired drum roaster -style conversion kit  

I tried this arrangement first and mechanically it worked just fine, but when lightening up the whole thing I noticed that the flames "backfire" against the alu-heat retender; with 660 C Al meting point maybe that isnt such a great idea => not recommended.

BR Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi,

OK, so this IR thermometer http://www.conrad.de/script/infrarot...eter_ir-37.sap arrived already and as promised here is the feedback for this roaster setup.
I didnt use the heat retention addition and just pointed the IR thermometer with about 10 cm distance into the open bowl. Fan was blowing across bowl.

The results are pretty much in agreeement what Bullitt and Javaphile were predicting: until about 200 C things were pretty consistent and stable and above 200 C / first crack I also get this 10 deg "flickering" of the temp readings. Nevertheless you can still see larger trends, like temps dropping after backoff of the HG after 1st crack.  So it has some use, even though you cant use it for exact control.

I also checked the setting of emittivity = 0.95 for coffee beans at some temps and compared against TC readings (in kitchen = "controlled environment").
I used green and rostaed beans at temps of 21, 48 100, 120 deg C and the TC vs IR readings where within 1.5 deg aligned. So coffe beans as such seem to be pretty much a "gray body radiator" with emittivity = 0.95 .

The "flickering" then comes as you said from smoke, winds, heat hitting the IR thermometer and all the other factors of the rough outside roasting environment...

Cheers, Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

I wonder if I have finally solved the problem how to attach the TC to this cement-mixer roaster  (of course this idea came just few days after the fancy IR thermometer has arrived .... :






I did some "dry" test, just letting the HG run for 10 min on the usual 70% power setting I use (not pointing into bowl, but just into air), and, luckily, the temp indication never went above 43 deg C. This means that the heat conducted away from the very hot nozzle doesnt seem to bias the head of the TC too much.

Need to go for a roast tomorrow and see how it works with the real setup...

Cheers, Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Did some test roasts today with the new TC installation, see yesterdays post. Works very well and the temp readings for 1st / 2nd crack match where they should be. I didnt notice any funny effects.
The thermometer is cheap one for oven, goes up to 300 deg C. I had to bend the stiff curved metal shaft in the end in order to guide it out of the heat rentention hole.

Now the whole setup is pretty much finished (see pic). With this temp control I seem to be able to control the roasts on the same level as eg with BM (when reading the zipped datalog stories), roast profiles are now pretty reproducible from roast to roast with only few deg difference over time. The roasts turn out to be very even.
I still need to figure best HG backoff setting after 1st crack, just as people pointed out, you easily overshoot the backoff, so its quite sensitive to the temp changes on the HG. If anybody here is interested I can post the manually obtained roast profiles.

There seem to be still lot of heat reserves in this setup: with the heat rentention used and 250 g roasts I need only  max 60% power on the 2kW HG, mostly running at 50 % and hopefully giving it long life. And I havent yet used the butan gas afterburner, this will be further area  for experiments, eg running it without HG and emulating a drum roaster.

Other area for experimentation is finding out best/maximum roast size.

Oh yes, and replacing the HG by a IR light source ...

So long,
Peter

[arcticroaster]

Re: Yet another handsfree HG setup: HG/iRB

Hi,

here is a pic of the latest version of the TC instrumentation, together with the heat retention lid. Not tested yet, plan is to have 4 TCs measure the bean temp and 2 the air temp above the bed.

Due to the localised heating from the HG, the strong convective airflow (HG nozzle only 2 .. 4 cm above bean bed) and the peculiar circular flow of the beans in the bowl, there are likely temp variations across the bean bed. This mod should be able to shed some light on this.

There may just not be any single "bean temperature" ...

Cheers, Peter