Earlier this week I posted about
the probe device Tije made for the CoffeeTech FZ94 coffee roaster to be inserted in the slider for the trier. Here's an update about the first roast done with this new probe.
First I warm up the roaster with Tije's trier BT probe device outside the machine and the regular trier in place. This way the probe remains at room temperature, just like the green beans, until the start of the roast.:
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| Warming up |
As expected, this works much like previous warmups. I use the on screen sliders in
Artisan to increase airflow (light blue MODBUS FAN line and brown FAN line in the graph) after 4, 7 and 10 minutes to keep the temperature of drum and air flowing out the roaster closely together. Meanwhile the BT probe remains stable at 17ºC room temp.
Then I load the background plan for the next roast:
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| Roast plan in the background |
I anticipate having to lift the background in case Tije's trier BT probe reports a higher value than in previous roast but as it happens the roast starts much as planned without any shifting around of the background plan. In the illustration below I have removed the background lines in order to clear up the tangle of lines for you:
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| Roast profile with new "trier" BT probe |
As you see in the graph, I insert
Tije's BT probe device at the same time as the green beans are charged into the roaster.
Consequently you can see the actual Bean Temperature rise from room temp just like one observes in fluid bed roaster profiles. Usually with drum roasters one does not get a relevant indication of the Bean Temp until the probe, hot from pre-heating, has dropped in temperature as the cool beans hit it, until Turning Point when the warmed up bean mass and the cooled down BT probe tip have acquired the same temperature and are jointly on the rise, as in the previous roast below:
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| Roast with conventional BT probe and TP at 2:06 and 110ºC |
One advantage of Tije's BT probe setup is the more realistic value of the displayed RoR (Rate of Rise) as seen again below. Especially the RoR of the first phase is now true, not obfuscated by the big dip and TP of the conventional drum roast style fixed BT probe.
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| Roast profile with Tije's "trier" BT probe, also with background plan |
At 8 minutes, when observing the jump in RoR that started at 7 minutes, I decide to shift the background plan to the left so the actual BT and the planned BT join again. You can see how the grey "roast plan" line is now above the BT line in 1-8 minutes when during those minutes it actually tracked nicely along the grey line.
Airflow as regulated by the PID in
Artisan remains high during that last phase, Drum Temp and Exhaust Temp (blue and black lines at the top) drop jointly after 9 minutes but there remains enough energy in the system and coming from the two active elements (the third switched off shortly after FC) to sustain the declining RoR.
The RoR is actually very gently declining all along which gives a slightly better result than I mostly got when the BT probe was in its conventional location.
I will need to do more roasts to see if this is consistently so.
(Fellow users of Artisan may notice a few new values at the bottom of this last illustration, one of them AUC=297C*min. This is a value representing the total Area Under Curve, an indication of the amount of energy that hit the bean mass during an essential portion of the roast. This and some related new features in the upcoming 1.0 of Artisan may assist roasters by introducing yet another instrument for consistency. Marko Luther will post all about it in his bog when it's ready to roll.)
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